Injurious Wildlife Species; Listing 10 Freshwater Fish and 1 Crayfish

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 16

[Docket No. FWS-HQ-FAC-2013-0095; FXFR13360900000-167-FF09F14000]

RIN 1018-AY69

Injurious Wildlife Species; Listing 10 Freshwater Fish and 1 Crayfish

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Final rule.

SUMMARY:

The U.S. Fish and Wildlife Service (Service) is amending its regulations to add to the list of injurious fish the following freshwater fish species: Crucian carp (

Carassius carassius

), Eurasian minnow (

Phoxinus phoxinus

), Prussian carp (

Carassius gibelio

), roach (

Rutilus rutilus

), stone moroko (

Pseudorasbora parva

), Nile perch (

Lates niloticus

), Amur sleeper (

Perccottus glenii

), European perch (

Perca fluviatilis

), zander (

Sander lucioperca

), and wels catfish (

Silurus glanis

). In addition, the Service also amends its regulations to add the freshwater crayfish species common yabby (

Cherax destructor

) to the list of injurious crustaceans. These listings will prohibit the importation of any live animal, gamete, viable egg, or hybrid of these 10 fish and 1 crayfish into the United States, except as specifically authorized. These listings will also prohibit the interstate transportation of any live animal, gamete, viable egg, or hybrid of these 10 fish and 1 crayfish between States, the District of Columbia, the Commonwealth of Puerto Rico, or any territory or possession of the United States, except as specifically authorized. These species are injurious to the interests of agriculture or to wildlife or the wildlife resources of the United States, and the listing will prevent the purposeful or accidental introduction, establishment, and spread of these 10 fish and 1 crayfish into ecosystems of the United States.

DATES:

This rule is effective on October 31, 2016.

ADDRESSES:

This final rule is available on the Internet at

http://www.regulations.gov

under Docket No. FWS-HQ-FAC-2013-0095. Comments and materials received, as well as supporting documentation used in the preparation of this rule, will also be available for public inspection by appointment during normal business hours at: U.S. Fish and Wildlife Service; 5275 Leesburg Pike; Falls Church, VA 22041.

FOR FURTHER INFORMATION CONTACT:

Susan Jewell, U.S. Fish and Wildlife Service, MS-FAC, 5275 Leesburg Pike, Falls Church, VA 22041-3803; 703-358-2416. If a telecommunications device for the deaf (TDD) is required, please call the Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

The U.S. Fish and Wildlife Service (Service) is amending its regulations to add to the list of injurious fish the following nonnative freshwater fish species: Crucian carp, Eurasian minnow, Prussian carp, roach, stone moroko, Nile perch, Amur sleeper, European perch, zander, and wels catfish. In addition, the Service is amending its regulations to add the common yabby, a nonnative freshwater crayfish species, to the list of injurious crustaceans. These listings prohibit the importation of any live animal, gamete, viable egg, or hybrid of these 10 fish and 1 crayfish (11 species) into the United States, except as specifically authorized. These listings also prohibit the interstate transportation of any live animal, gamete, viable egg, or hybrid of these 10 fish and 1 crayfish, except as specifically authorized. With this final rule, the importation and interstate transportation of any live animal, gamete, viable egg, or hybrid of these 10 fish and 1 crayfish may be authorized only by permit for scientific, medical, educational, or zoological purposes, or without a permit by Federal agencies solely for their own use. This action is necessary to protect the interests of agriculture, wildlife, or wildlife resources from the purposeful or accidental introduction, establishment, and spread of these 11 species into ecosystems of the United States.

On October 30, 2015, we published a proposed rule in the

Federal Register

(80 FR 67026) to add the 11 species to the list of injurious fish and crustaceans as injurious wildlife under the Lacey Act (the Act; 18 U.S.C. 42, as amended) and announced the availability of the draft economic analysis and the draft environmental assessment of the proposed rule. The 60-day comment period ended on December 29, 2015. We also solicited peer review at the same time. In this final rule, we used public comments and peer review to inform our final determinations.

The need for the action to add 11 nonnative species to the list of injurious wildlife under the Lacey Act developed from the Service's concern that, through our rapid screen process, these 11 species were categorized as “high risk” for invasiveness. A species does not have to be currently imported or present in the United States for the Service to list it as injurious. All 11 species have a high climate match in parts of the United States, a history of invasiveness outside their native ranges, and, except for one fish species in one lake, are not currently found in U.S. ecosystems. Nine of the freshwater fish species (Amur sleeper, crucian carp, Eurasian minnow, European perch, Prussian carp, roach, stone moroko, wels catfish, and zander) have been introduced to and established populations within Europe and Asia, where they have spread and are causing harm. The Nile perch has been introduced to and become invasive in new areas of central Africa. The common yabby has been introduced to western Australia and to Europe where it has established invasive populations. Most of these species were originally introduced for aquaculture, recreational fishing, or ornamental purposes. Two of these fish species (the Eurasian minnow and stone moroko) were accidentally introduced when they were unintentionally transported in shipments with desirable fish species stocked for aquaculture or fisheries management.

Based on our evaluation under the Act of all 11 species, the Service seeks to prevent the introduction, establishment, and spread within the United States of each species by adding them all to the Service's lists of injurious wildlife, thus prohibiting both their importation and interstate transportation. We take this action to prevent injurious effects, which is consistent with the Lacey Act.

We evaluated the 10 fish and 1 crayfish species using the Service's Injurious Wildlife Evaluation Criteria. The criteria include the likelihood and magnitude of release or escape, of survival and establishment upon release or escape, and of spread from origin of release or escape. The criteria also examine the effect on wildlife resources and ecosystems (such as through hybridizing, competition for food or habitat, predation on native species, and pathogen transfer), on endangered and threatened species and their respective habitats, and on human beings, forestry, horticulture, and agriculture. Additionally, criteria evaluate the likelihood and magnitude of wildlife or habitat damages resulting from control measures. The analysis using these criteria serves as a basis for the Service's regulatory decision regarding injurious wildlife species listings.

Each of these 11 species has a well-documented history of invasiveness outside of its native range, but not in the United States. When released into the

environment, these species have survived and established, expanded their nonnative range, preyed on native wildlife species, and competed with native species for food and habitat. Since it would be difficult to eradicate, manage, or control the spread of these 11 species; it would be difficult to rehabilitate or recover habitats disturbed by these species; and because introduction, establishment, and spread of these 11 species would negatively affect agriculture, and native wildlife or wildlife resources, the Service is amending its regulations to add these 11 species as injurious under the Lacey Act. This listing prohibits the importation and interstate transportation of any live animal, gamete, viable egg, or hybrid in the United States, except as specifically authorized.

The Service solicited three independent scientific peer reviewers who all submitted individual comments in written form. We also received comments from 20 State agencies, regional and U.S.-Canada governmental alliances, commercial businesses, conservation organizations, nongovernmental organizations, and private citizens during the 60-day public comment period. We reviewed all comments for substantive issues and new information regarding the proposed designation of the 11 species as injurious wildlife. None of the peer or public comments necessitated any substantive changes to the rule, the environmental assessment, or the economic analysis. Comments received provided a range of opinions on the proposed listing: (1) Unequivocal support for the listing with no additional information included; (2) unequivocal support for the listing with additional information provided; (3) equivocal support for the listing with or without additional information included; and (4) unequivocal opposition to the listing with additional information included. We consolidated comments and our responses into key issues in the “Summary of Comments Received on the Proposed Rule” section.

This final rule is not significant under Executive Order (E.O.) 12866. E.O. 12866 Regulatory Planning and Review (Panetta 1993) and the subsequent document, Economic Analysis of Federal Regulations under E.O. 12866 (U.S. Office of Management and Budget 1996) require the Service to ensure that proper consideration is given to the effect of this final action on the business community and economy. With respect to the regulations under consideration, analysis that comports with the Circular A-4 would include a full description and estimation of the economic benefits and cost associated with the implementation of the regulations. The economic effects to three groups would be addressed: (1) Producers; (2) consumers; and (3) society. Of the 11 species, only one population of one species (zander) is found in the wild in the United States. Of the 11 species, 4 species (crucian carp, Nile perch, wels catfish, yabby) have been imported in small numbers since 2011, and 7 species are not in U.S. trade. To our knowledge, the total number of importation events of those 4 species from 2011 to 2015 is 25, with a declared total value of $5,789. Therefore, the economic effect in the United States is negligible for those four species and nil for the seven not in trade. The final economic analysis that the Service prepared supports this conclusion (USFWS Final Economic Analysis 2016).

Previous Federal Actions

On October 30, 2015, we published a proposed rule in the

Federal Register

(80 FR 67026) to list the crucian carp, Eurasian minnow, Prussian carp, roach, stone moroko, Nile perch, Amur sleeper, European perch, zander, wels catfish, and common yabby to the list of injurious fish and crustaceans as injurious wildlife under the Act. The proposed rule established a 60-day comment period ending on December 29, 2015, and announced the availability of the draft economic analysis and the draft environmental assessment of the proposed rule. We also solicited peer review at the same time.

For the injurious wildlife evaluation in this final rule, in addition to information used for the proposed rule, we considered: (1) Comments from the public comment period for the proposed rule, (2) comments from three peer reviewers, and (3) new information acquired by the Service by the end of the public comment period. We present a summary of the peer review comments and the public comments and our responses to them following the Lacey Act Evaluation Criteria section in this final rule.

Summary of Changes From the Proposed Rule

We fully considered comments from the public and the peer reviewers on the proposed rule. This final rule incorporates changes to our proposed rule based on the comments we received that are discussed under Summary of Comments Received on the Proposed Rule and newly available information that became available after the close of the comment period. Specifically, we made one change to the common yabby that did not result in a change to the final determination to that species but may be worth singling out. We removed “

Potential Impacts to Humans

” as one of the factors for considering the yabby as injurious. We found that while the common yabby may directly impact human health by transferring metal contaminants through consumption and may require consumption advisories, these advisories are not expected to be more stringent than those for crayfish species that are not considered injurious. Therefore, none of the 11 species in this final rule is being listed as injurious wildlife because of potential impacts to humans.

Background

The regulations contained in 50 CFR part 16 implement the Act. Under the terms of the Act, the Secretary of the Interior is authorized to prescribe by regulation those wild mammals, wild birds, fish, mollusks, crustaceans, amphibians, reptiles, and the offspring or eggs of any of the foregoing that are injurious to human beings, to the interests of agriculture, horticulture, forestry, or to wildlife or the wildlife resources of the United States. The lists of injurious wildlife species are found in title 50 of the Code of Federal Regulations (CFR) at §§ 16.11 through 16.15.

The purpose of listing the crucian carp, Eurasian minnow, Prussian carp, roach, stone moroko, Nile perch, Amur sleeper, European perch, zander, and wels catfish and the common yabby (hereafter “11 species”) as injurious wildlife is to prevent the harm that these species could cause to the interests of agriculture, wildlife, and wildlife resources through their accidental or intentional introduction, establishment, and spread into the wild in the United States. The Service evaluated each of the 11 species individually, and we determined each species to be injurious based on its own traits.

Consistent with the statutory language and congressional intent, it is the Service's longstanding and continued position that the Lacey Act prohibits both the importation into the United States and all interstate transportation between States, the District of Columbia, the Commonwealth of Puerto Rico, or any territory or possession of the United States, including interstate transportation between States within the Continental United States, of injurious wildlife, regardless of the preliminary injunction decision in

U.S. Association of Reptile Keepers

v.

Jewell,

No. 13-2007 (D.D.C. May 12, 2015). The

Service's interpretation of 18 U.S.C. 42(a)(1) finds support in the plain language of the statute, the Lacey Act's purpose, legislative history, and congressional ratification. First, the statute's use of the disjunctive “or” to separate the listed geographic entities indicates that each location has independent significance. Second, Congress enacted the Lacey Act in 1900 for the purpose of, among other things, regulating the introduction of species in localities, not merely large territories, where they have not previously existed. See 16 U.S.C. 701. Third, the legislative history of Congress' many amendments to the Lacey Act since its enactment in 1900 shows that Congress intended, from the very beginning, for the Service to regulate the interstate shipment of certain injurious wildlife. Finally, recent Congresses have made clear that Congress interprets 18 U.S.C. 42(a)(1) as prohibiting interstate transport of injurious wildlife between the States within the continental United States. In amending § 42(a)(1) to add zebra mussels and bighead carp as injurious wildlife without making other changes to the provision, Congress repeated and ratified the Service's interpretation of the statute as prohibiting all interstate transport of injurious species.

The prohibitions on importation and all interstate transportation are both necessary to prevent the introduction, establishment, and spread of injurious species that threaten human health or the interests of agriculture, horticulture, forestry, or the wildlife or wildlife resources of the United States. By listing these 11 species as injurious wildlife, both the importation into the United States and interstate transportation between States, the District of Columbia, the Commonwealth of Puerto Rico, or any territory or possession of the United States of live animals, gametes, viable eggs, or hybrids is prohibited, except by permit for zoological, educational, medical, or scientific purposes (in accordance with permit regulations at 50 CFR 16.22), or by Federal agencies without a permit solely for their own use, upon filing a written declaration with the District Director of Customs and the U.S. Fish and Wildlife Service Inspector at the port of entry. In addition, no live specimens of these 11 species, gametes, viable eggs, or hybrids imported or transported under a permit could be sold, donated, traded, loaned, or transferred to any other person or institution unless such person or institution has a permit issued by the Service. The rule would not prohibit intrastate transport of the listed fish or crayfish species. Any regulations pertaining to the transport or use of these species within a particular State would continue to be the responsibility of that State.

How the 11 Species Were Selected for Consideration as Injurious Species

While the Service recognizes that not all nonnative species become invasive, it is important to have some understanding of the risk that nonnative species pose to the United States. The Ecological Risk Screening Summary (ERSS) approach was developed to address the need described in the National Invasive Species Management Plan (NISC 2008). The Plan states that prevention is the first-line of defense. One of the objectives in the Plan is to “[d]evelop fair and practical screening processes that evaluate different types of species moving intentionally in trade.” The ERSS process, and the associated Risk Assessment Mapping Program, were peer-reviewed by risk assessment experts from the United States, Canada, and Mexico. Those experts support the use of those tools for U.S. national risk assessment, and associated risk management. The Service utilizes a rapid screening process to provide a prediction of the invasive potential of nonnative species and to prioritize which species to consider for listing. Rapid screens categorize risk as either high, low, or uncertain and have been produced for two thousand foreign aquatic fish and invertebrates for use by the Service and other entities. Each rapid screen is summarized in an Ecological Risk Screening Summary (ERSS; see “Rapid Screening” below for explanation regarding how these summaries were done). The Service selected 11 species with a rapid screen result of “high risk” to consider for listing as injurious. We put these 11 species through a subsequent risk analysis to evaluate each species for injuriousness (see “Injurious Wildlife Evaluation Criteria” section below).

These 11 species have a high climate match (see Rapid Screening) in parts of the United States, a history of invasiveness outside of their native range (see

Need for the Final Rule

), are not yet found in U.S. ecosystems (except for one species in one lake), and have a high degree of certainty regarding these results. The ERSS reports for each of the 11 species are available on the Service's Web site (

http://www.fws.gov/injuriouswildlife/Injurious_prevention.html

).

The practice of using history of invasiveness and climate match to determine risk has been validated in peer-reviewed studies over the years. Here are some examples: Kolar and Lodge (2002) found that discriminant analysis revealed that successful fishes in the establishment stage grew relatively faster, tolerated wider ranges of temperature and salinity, and were more likely to have a history of invasiveness than were failed fishes. They also correlated traits of invasiveness with stages of invasion to predict rate of spread for specific species and predicted that the roach, Eurasian minnow, and European perch would spread quickly, while the zander would spread slowly (the other seven species in this final rule were not studied). Hayes and Barry (2008) found that climate and habitat match, history of successful invasion, and number of arriving and released individuals are consistently associated with successful establishment. Bomford

et al.

(2010) found that “Relative to failed species, established species had better climate matches between the country where they were introduced and their geographic range elsewhere in the world. Established species were also more likely to have high establishment success rates elsewhere in the world.” Recently, Howeth

et al.

(2016) showed that climate match between a species' native range and the Great Lakes region predicted establishment success with 75 to 81 percent accuracy.

All 11 species are documented to be highly invasive internationally (see Species Information for each species). Nine of the freshwater fish species (Amur sleeper, crucian carp, Eurasian minnow, European perch, Prussian carp, roach, stone moroko, wels catfish, and zander) have been introduced and established populations within Europe and Asia. The Prussian carp was recently found to be established in waterways in southern Alberta, Canada (Elgin

et al.

2014), near the U.S. border. Another freshwater fish species, the Nile perch, has been introduced to and become invasive in new areas of central Africa. The freshwater crayfish, the common yabby, has been introduced to and established populations in new areas of Australia and in Europe. Most of the 11 species were originally intentionally introduced for aquaculture, recreational fishing, or ornamental purposes. The Eurasian minnow and the stone moroko were accidentally mixed with and introduced with shipments of fish stocked for other intended purposes.

Need for the Final Rule

Consistent with 18 U.S.C. 42, the Service aims to prevent the introduction, establishment, and spread of all 11 species within the United States due to concerns regarding the

potential injurious effects of the 11 species on the interests of agriculture or to wildlife or wildlife resources of the United States. The threat posed by these 11 species is evident in their history of invasiveness (establishment and spread) in other countries and their high risk of establishment as demonstrated by a high climate match within the United States.

All of these species have wide distribution ranges where they are native and where they are invasive, suggesting they are highly adaptable and tolerant of new environments and opportunistic when expanding from their native range. Based on the results of rapid screening assessments and our injurious wildlife evaluation, we anticipate that these 11 species will become invasive if they are introduced into waters of the United States. Furthermore, if introduced and established in one area of the United States, these species could then spread to other areas of the country through unintentional or intentional interstate transport, such as for aquaculture, recreational and commercial fishing, bait, ornamental display, and other possible uses.

Listing Process

The Service promulgates regulations under the Act in accordance with the Administrative Procedure Act (APA; 5 U.S.C. 551

et seq.

). We published a proposed rule for public notice and comment. We solicited peer review under Office of Management and Budget (OMB) guidelines “Final Information Quality Bulletin for Peer Review” (OMB 2004). We also prepared a draft economic analysis (including analysis of potential effects on small businesses) and a draft environmental assessment, both of which we made available to the public. For this final rule, we prepared a final economic analysis and a final environmental assessment.

This final rule is based on an evaluation using the Service's Injurious Wildlife Evaluation Criteria (see Injurious Wildlife Evaluation Criteria, below, for more information). We use these criteria to evaluate whether a species does or does not qualify as injurious under the Act. These criteria include the likelihood and magnitude of release or escape, of survival and establishment upon release or escape, and of spread from origin of release or escape. These criteria also examine the impact on wildlife resources and ecosystems (such as through hybridizing, competition for food or habitat, predation on native species, and pathogen transfer), on endangered and threatened species and their respective habitats, and on human beings, forestry, horticulture, and agriculture. Additionally, criteria evaluate the likelihood and magnitude of wildlife or habitat damages resulting from measures to control the proposed species. The analysis using these criteria serves as a basis for the Service's regulatory decision regarding injurious wildlife species listings. The objective of such a listing is to prohibit importation and interstate transportation and thus prevent the species' likely introduction, establishment, and spread in the wild, thereby preventing injurious effects consistent with 18 U.S.C. 42.

We evaluated each of the 11 species individually and are listing all 11 species because we determined each of these species to be injurious. The final rule contains responses to comments we received on the proposed rule, states the final decision, and provides the justification for that decision. Each of the species determined to be injurious will be added to the list of injurious wildlife found in 50 CFR 16.13.

To assist us with making our determination under the injurious wildlife evaluation criteria, we used information from available sources, including the Centre for Agricultural Bioscience International (CABI) reports (called full datasheets) from their Invasive Species Compendium (CABI ISC) that were specific to each species for biological and invasiveness information as well as primary literature and import data from our Office of Law Enforcement.

Introduction Pathways for the 11 Species

The primary potential pathways for the 11 species into the United States are through commercial trade in the live animal industry, including aquaculture, recreational fishing, bait, and ornamental display. Some could arrive unintentionally in water used to carry other aquatic species. Aquatic species may be imported into many designated ports of entry, including Miami, Los Angeles, Baltimore, Dallas-Fort Worth, Detroit, Chicago, and San Francisco. Once imported, aquatic species could be transported throughout the country for aquaculture, recreational and commercial fishing, bait, display, and other possible uses.

Aquaculture is the farming of aquatic organisms, such as fish, crustaceans, mollusks, and plants, for food, pets, stocking for fishing, and other purposes. Aquaculture usually occurs in a controlled setting where the water is contained, as a pond or in a tank, and is separate from lakes, ponds, rivers, and other natural waters. The controlled setting allows the aquaculturist to maintain proper conditions for each species being raised, which promotes optimal feeding and provides protection from predation and disease. However, Bartley (2011) states that aquaculture is the primary reason for the deliberate movement of aquatic species outside of their range, and Casal (2006) states that many countries are turning to aquaculture for human consumption, and that has led to the introduction and establishment of these species in local ecosystems. Although the farmed species are normally safely contained, outdoor aquaculture ponds have often flooded from major rainfall events and merged with neighboring natural waters, allowing the farmed species to escape by swimming or floating to nearby watersheds. Once a species enters a watershed, it has the potential to establish and spread throughout the watershed, which then increases the risk of spread to neighboring watersheds through further flooding. Other pathways for aquaculture species to enter natural waters include intentional stocking programs, and through unintentional stocking when the species is inadvertently included in a shipment with an intended species for stocking (Bartley 2011), release of unwanted ornamental fish, and release of live bait by fishermen.

Stocking for recreational fishing is a common pathway for invasive species when an aquatic species is released into a water body where it is not native. Often it takes repeated releases before the fish (or other animal) becomes established. The type of species that are typically selected and released for recreational fishing are predatory, grow quickly and to large sizes, reproduce abundantly, and are adaptable to many habitat conditions (Fuller

et al.

1999). These are often the traits that also contribute to the species becoming invasive (Copp

et al.

2005c; Kolar and Lodge 2001, 2002).

Live aquatic species, such as fish and crayfish, are frequently used as bait for recreational and commercial fishing. Generally, bait animals are kept alive until they are needed, and leftover individuals may be released into convenient waterbodies (Litvak and Mandrak, 1993; Ludwig and Leitch, 1996). For example, Kilian

et al.

(2012) reported that 65 and 69 percent of Maryland anglers using fishes and crayfishes, respectively, released their unused bait, and that a nonnative, potentially invasive species imported into the State as bait is likely to be released into the wild. Often, these individuals survive, establish, and cause

harm to that waterbody (Fuller

et al.

1999; Kilian

et al.

2012).

Litvak and Mandrak (1993) found that 41 percent of anglers released live bait after use. Their survey found nearly all the anglers who released their bait thought they were doing a good thing for the environment. When the authors examined the purchase location and the angling destination, they concluded that 18 of the 28 species found in the dealers' bait tanks may have been used outside their native range. Therefore, it is not surprising that so many species are introduced in this manner; Ontario, Canada, alone has more than 65 legal baitfish species, many of which are not native to some or all of Ontario (Cudmore and Mandrak 2005). Ludwig and Leitch (1996) concluded that the probability of at least 1,000 bait release events from the Mississippi Basin to the Hudson Bay Basin in 1 year is close to 1 (a certainty).

Ornamental aquatic species are species kept in aquaria and aquatic gardens for display for entertainment or public education. The first tropical freshwater fishes became available in trade in the United States in the early 1900s (Duggan 2011), and there is currently a large variety of freshwater and saltwater fishes in the ornamental trade. The trade in ornamental crayfish species is more recent but is growing rapidly (Gherardi 2011). The most sought-after species frequently are not native to the display area. Ornamental species may accidentally escape from outdoor ponds into neighboring waterbodies (Andrews 1990; Fuller

et al.

1999; Gherardi 2011). They may also be released outdoors intentionally when owners no longer wish to maintain them, despite laws in most States prohibiting release into the wild.

The invasive range of many of the species in this final rule has expanded through intentional release for commercial and recreational fishing (European perch, Nile perch, Prussian carp, roach, wels catfish, zander, and common yabby), as bait (Eurasian minnow, roach, common yabby), and as ornamental fish (Amur sleeper, stone moroko), and unintentionally (Amur sleeper, crucian carp, Eurasian minnow, and stone moroko) with shipments of other aquatic species. All 11 species have proven that they are capable of naturally dispersing through waterways.

The main factor influencing the chances of these 11 species establishing in the wild would be the propagule pressure, defined as the frequency of release events (propagule number) and numbers of individuals released (propagule size) (Williamson 1996; Colautti and MacIsaac 2004; Duncan 2011). This factor increases the odds of both genders being released and finding mates and of those individuals being healthy and vigorous. After a sufficient number of unintentional or intentional releases, a species may establish in those regions suitable for its survival and reproduction. Thus, continuing to allow the importation and interstate transport of these 11 species subsequently increases the risk of any of these species becoming established and spreading in the United States.

An additional factor indicating an invasive species' likelihood of successful establishment and spread is a documented history of these same species successfully establishing and spreading elsewhere outside of their native ranges. All 11 species have been introduced, become established, and been documented as causing harm in countries outside of their native ranges. For example, the stone moroko's native range includes southern and central Japan, Taiwan, Korea, China, and the Amur River basin (Copp

et al.

2010). Since the stone moroko's original introduction to Romania in the early 1960s, this species has invaded nearly every European country and additional regions of Asia (Welcomme 1988; Copp

et al.

2010; Froese and Pauly 2014g).

The demonstrated ability of each of these species to become established, spread, and cause harm outside of their native range, in conjunction with the risk they would pose to U.S. ecosystems, warrants listing all 11 species as injurious under the Lacey Act. The objective of this listing is to prohibit importation and interstate transportation of these species and thus prevent their likely introduction, establishment, and spread in the wild and associated harms to the interests of agriculture, or wildlife or wildlife resources of the United States.

Species Information

We obtained our information on a species' biology, history of invasiveness, and climate matching from a variety of sources, including the U.S. Geological Survey Nonindigenous Aquatic Species (NAS) database, CABI datasheets, ERSS reports, primary literature, and peer and public comments. We queried the NAS database (

http://nas.er.usgs.gov/

) to confirm that 10 of the 11 species are not currently established in U.S. ecosystems. The zander is established in a lake in North Dakota (Fuller 2009). The CABI ISC (

http://www.cabi.org/isc/

) is an encyclopedic resource containing datasheets on more than 1,500 invasive species and animal diseases. The Service contracted with CABI for many of the species-specific datasheets that we used in preparation of this final rule. The datasheets were prepared by experts on the species, and each datasheet was reviewed by expert peer reviewers.

Crucian Carp (Carassius carassius)

The crucian carp was first described and cataloged by Linnaeus in 1758, and is part of the order Cypriniformes and family Cyprinidae (ITIS 2014). The family Cyprinidae, or the carp and minnow family, is a large and diverse group that includes 2,963 freshwater species (Froese and Pauly 2014d). The taxonomic status of the crucian carp has been reported to be confused and it is commonly misidentified with other

Carassius spp.

(Godard and Copp 2012).

Native Range and Habitat

The crucian carp inhabits a temperate climate (Riehl and Baensch 1991). The native range includes much of north and central Europe, extending from the North Sea and Baltic Sea basins across northern France and Germany to the Alps and through the Danube River basin and eastward to Siberia (Godard and Copp 2012). The species inhabits freshwater lakes, ponds, rivers, and ditches (Godard and Copp 2012). This species can survive in water with low dissolved oxygen levels, including aquatic environments with greatly reduced oxygen (hypoxic) or largely devoid of dissolved oxygen (anoxic) (Godard and Copp 2012).

Nonnative Range and Habitat

Crucian carp have been widely introduced to and established in Croatia, Greece, southern France (Holčík 1991; Godard and Copp 2012), Italy, and England (Kottelat and Freyhof 2007), Spain, Belgium, Israel, Switzerland, Chile, India, Sri Lanka, Philippines (Holčík 1991; Froese and Pauly 2014a), and Turkey (Innal and Erk'akan 2006). In the United States, crucian carp may have been established within Chicago (Illinois) lakes and lagoons in the early 1900s (Meek and Hildebrand 1910; Schofield

et al.

2005), but they apparently died out because currently no such population exists (Welcomme 1988; Schofield

et al.

2005; Schofield

et al.

2013).

Several other fish species, including the Prussian carp, the common carp (

Cyprinus carpio

), and a brown variety of goldfish (

Carassius auratus

) have been misidentified as crucian carp (Godard and Copp 2012). Crucian carp may have been accidentally introduced to some regions in misidentified shipments of ornamental fishes (Wheeler 2000; Hickley and Chare 2004). However, no known populations

of crucian carp currently exist in the United States.

Biology

Crucian carp generally range from 20 to 45 centimeters (cm) (8 to 18 inches (in)) long with a maximum of 50 cm (19.5 in) (Godard and Copp 2012). Specimens have been reported to weigh up to 3 kilograms (kg) (6.6 pounds (lb)) (Froese and Pauly 2014a). These fish have an olive-gray back that transitions into brassy green along the sides and brown on the body (Godard and Copp 2012).

Crucian carp can live up to 10 years (Kottelat and Freyhof 2007) and reach sexual maturity at one and a half years but may not begin spawning until their third year (Godard and Copp 2012). Crucian carp are batch spawners (release multiple batches of eggs per season) and may spawn one to three times per year (Aho and Holopainen 2000, Godard and Copp 2012).

Crucian carp feed during the day and night on plankton, benthic (bottom-dwelling) invertebrates, plant materials, and detritus (organic material) (Kottelat and Freyhof 2007).

Crucian carp can harbor the virus causing the fish disease Spring Viraemia of Carp (SVC) (Ahne

et al.

2002) and several parasitic infections (

Dactylogyrus

gill flukes disease, Trichodinosis, skin flukes, false fungal infection (

Epistylis

sp.), and turbidity of the skin) (Froese and Pauly 2014b). SVC is a disease that, when found, is required to be reported to the Office International des Epizooties (OIE) (World Organisation of Animal Health) (Ahne

et al.

2002). The SVC virus infects carp species but may be transmitted to other fish species. The virus is shed with fecal matter and urine, and often infects through waterborne transmission (Ahne

et al.

2002). Additionally, SVC may result in significant morbidity and mortality with an approximate 70 percent fatality among juvenile fish and 30 percent fatality in adult fish (Ahne

et al.

2002). Thus, the spread of SVC may have serious effects on native fish stocks.

OIE-notifiable diseases affect animal health internationally. OIE-notifiable diseases meet certain criteria for consequences, spread, and diagnosis. For the consequences criteria, the disease must have either been documented as causing significant production losses on a national or multinational (zonal or regional) level, or have scientific evidence that indicates that the diseases will cause significant morbidity or mortality in wild aquatic animal populations, or be an agent of public health concern. For the spread criteria, the disease's infectious etiology (cause) must be known or an infectious agent is strongly associated with the disease (with etiology unknown). In addition for the spread criteria, there must be a likelihood of international spread (via live animals and animal products) and the disease must not be widespread (several countries or regions of countries without specific disease). For the diagnosis criteria, there must be a standardized, proven diagnostic test for disease detection (OIE 2012). These internationally accepted standards, including those that document the consequences (harm) of certain diseases, offer supporting evidence of injuriousness.

Invasiveness

This species demonstrates many of the strongest traits for invasiveness. The crucian carp is capable of securing and ingesting a wide range of food, has a broad native range, and is highly adaptable to different environments (Godard and Copp 2012). While foraging along the substrate, Crucian carp can increase turbidity (cloudiness of water) in lakes, rivers, and streams with soft bottom sediments. Increased turbidity reduces light availability to submerged plants and can result in harmful ecosystem changes, such as to phytoplankton survival and nutrient cycling. Crucian carp can breed with other carp species, including the common carp (Wheeler 2000). Hybrids of crucian carp and common carp can affect fisheries, because such hybrids, along with the introduced crucian carp, may compete with native species for food and habitat resources (Godard and Copp 2012).

Eurasian Minnow (Phoxinus phoxinus)

The Eurasian minnow was first described and cataloged by Linnaeus in 1758, and belongs to the order Cypriniformes and family Cyprinidae (ITIS 2014). Although Eurasian minnow is the preferred common name, this fish species is also referred to as the European minnow.

Native Range and Habitat

The Eurasian minnow inhabits a temperate climate, and the native range includes much of Eurasia within the basins of the Atlantic, North and Baltic Seas, and the Arctic and the northern Pacific Oceans (Froese and Pauly 2014e).

Eurasian minnows can be found in a variety of habitats ranging from brackish (estuarine; slightly salty) to freshwater streams, rivers, ponds, and lakes located within the coastal zone to the mountains (Sandlund 2008). In Norway, they are found at elevations up to 2,000 m (6,562 ft). These minnows prefer shallow lakes or slow-flowing streams and rivers with stony substrate (Sandlund 2008).

Nonnative Range and Habitat

The Eurasian minnow's nonnative range includes parts of Sweden and Norway, United Kingdom, and Egypt (Sandlund 2008), as well as other drainages juxtaposed to native waterways. The Eurasian minnow was initially introduced as live bait, which was the main pathway of introduction throughout the 1900s (Sandlund 2008). The inadvertent inclusion of this minnow species in the transport water of brown trout (

Salmo trutta

) that were intentionally stocked into lakes for recreational angling has contributed to their spread (Sandlund 2008). From these initial stockings, minnows have dispersed naturally downstream and established in new waterways, and have spread to new waterways through tunnels constructed for hydropower development. These minnows have also been purposely introduced as food for brown trout and to control the Tune fly (in Simuliidae) (Sandlund 2008).

The Eurasian minnow is expanding its nonnative range by establishing populations in additional waterways bordering the native range. Waterways near where the minnow is already established are most at risk (Sandlund 2008).

Biology

The Eurasian minnow has a torpedo-shaped body measuring 6 to 10 cm (2.3 to 4 in) with a maximum of 15 cm (6 in). Size and growth rate are both highly dependent on population density and environmental factors (Lien 1981; Mills 1987, 1988; Sandlund 2008). These minnows have variable coloration but are often brownish-green on the back with a whitish stomach and brown and black blotches along the side (Sandlund 2008).

The Eurasian minnow's life-history traits (age, size at sexual maturity, growth rate, and lifespan) may be highly variable (Mills 1988). Populations residing in lower latitudes often have smaller body size and younger age of maturity than those populations in higher altitudes and latitudes (Mills 1988). Maturity ranges from less than 1 year to 6 years of age, with a lifespan as long as 13 to 15 years (Sandlund 2008). The Eurasian minnow spawns annually with an average fecundity between 200 to 1,000 eggs (Sandlund 2008).

This minnow usually cohabitates with salmonid fishes (Kottelat and Freyhof

2007). The Eurasian minnow feeds mostly on invertebrates (crustaceans and insect larvae) as well as some algal and plant material (Lien 1981).

Invasiveness

The Eurasian minnow demonstrates many of the strongest traits for invasiveness. The species is highly adaptable to new environments and is difficult to control (Sandlund 2008). The species can become established within varying freshwater systems, including lowland and high alpine areas, as well as in brackish water (Sandlund 2008). Introductions of the Eurasian minnow can cause major changes to nonnative ecosystems by affecting the benthic community (decreased invertebrate diversity) and disrupting trophic-level structure (Sandlund 2008). This occurrence affects the ability of native fish to find food as well as disrupts native spawning. The Eurasian minnow has been shown to reduce recruitment of brown trout by predation (Sandlund 2008). Although brown trout are not native to the United States, they are closely related to our native trout and salmon, and thus Eurasian minnows could be expected to reduce the recruitment of native trout.

In addition, Eurasian minnows are carriers of parasites and have increased the introduction of parasites to new areas. Such parasites affected native snails, mussels, and different insects within subalpine lakes in southern Norway following introduction of the Eurasian minnows (Sandlund 2008). Additionally, Zietara

et al.

(2008) used molecular methods to link the parasite

Gyrodactylus aphyae

from Eurasian minnows to the new hosts of Atlantic salmon (

Salmo salar

) and brown trout.

Prussian Carp (Carassius gibelio)

The Prussian carp was first described and catalogued by Bloch in 1782, and belongs to the order Cypriniformes and family Cyprinidae (ITIS 2014). While some have questioned the taxonomy of Prussian carp, genetic studies have suggested that it is distinct Carassius species (Elgin et al. 2014). However, the species is not monophyletic (characterized by descent from a single ancestral group) and therefore possibly two distinct species (Kalous et al. 2012, Elgin et al. 2014). In fact, one clade (represents a single lineage) of Prussian carp is more closely related to goldfish (

C. auratus

) than to the second clade of Prussian carp (Kalous et al. 2012). The Prussian carp is very similar in appearance to other

Carassius spp.

and common carp (

Cyprinus carpio

), and are often difficult to differentiate (Britton 2011).

Native Range and Habitat

The Prussian carp inhabits a temperate climate (Baensch and Riehl 2004). The species is native to regions of central Europe and eastward to Siberia. It is also native to several Asian countries, including China, Georgia, Kyrgyzstan, Mongolia, Turkey, and Turkmenistan (Britton 2011). The Prussian carp resides in a variety of fresh stillwater bodies and rivers. This species also inhabits warm, shallow, eutrophic (high in nutrients) waters with submerged vegetation or regular flooding events (Kottelat and Freyhof 2007). This species can live in polluted waters with pollution and low oxygen concentrations (Britton 2011).

Nonnative Range and Habitat

The Prussian carp has been introduced to many countries within central and Western Europe. This species was first introduced to Belgium during the 1600s and is now prevalent in its freshwater systems. The Prussian carp was also introduced to Belarus and Poland during the 1940s for recreational fishing and aquaculture. This carp species has dispersed and expanded its range using the Vistula and Bug River basins (Britton 2011). During the mid to late 1970s, this carp species invaded the Czech Republic river system from the Danube River via the Morava River. Once in the river system, the fish expanded into tributary streams and connected watersheds. Throughout its nonnative range, this species has been stocked with common carp and misidentified as crucian carp (Britton 2011). From the original stocked site, the Prussian carp has dispersed both naturally and with human involvement.

The Prussian carp's current nonnative range includes the Asian countries of Armenia, Turkey, and Uzbekistan and the European countries of Belarus, Belgium, Czech Republic, Denmark, Estonia, France, Germany, Poland, and Switzerland (Britton 2011). The species has recently invaded the Iberian Peninsula (Ribeiro

et al.

2015). The species was recently found to be established in waterways in southern Alberta, Canada (Elgin

et al.

2014).

Biology

The Prussian carp has a silvery-brown body with an average length of 20 cm (7.9 in) and reported maximum length of 35 cm (13.8 in) (Kottelat and Freyhof 2007, Froese and Pauly 2014c). This species has a reported maximum weight of 3 kilograms (kg; 6.6 pounds (lb) (Froese and Pauly 2014c)).

The Prussian carp lives up to 10 years (Kottelat and Freyhof 2007). This species can reproduce in a way very rare among fish. Introduced populations often include, or are solely composed of, triploid females that can undergo natural gynogenesis, allowing them to use the sperm of other species to activate (but not fertilize) their own eggs (Vetemaa

et al.

2005, Britton 2011). Thus, the eggs are viable without being fertilized by male Prussian carp.

The Prussian carp is a generalist omnivore and consumes a varied diet that includes plankton, benthic invertebrates, plant material, and detritus (Britton 2011).

The parasite

Thelohanellus wuhanensis

(Wang

et al.

2001) and black spot disease (Posthodiplostomatosis) have been found to affect the Prussian carp (Markovíc

et al.

2012).

Invasiveness

The Prussian carp is a highly invasive species in freshwater ecosystems throughout Europe and Asia. This fish species grows rapidly and can reproduce from unfertilized eggs (Vetemaa

et al.

2005). Prussian carp have been implicated in the decline in both the biodiversity and population of native fish (Vetemaa

et al.

2005, Lusk

et al.

2010). The presence of this fish species has been linked with increased water turbidity (Crivelli 1995), which in turn alters both the ecosystem's trophic-level structure and nutrient availability.

Roach (Rutilus rutilus)

The roach was first described and cataloged by Linnaeus in 1758, and belongs to the order Cypriniformes and family Cyprinidae (ITIS 2014).

Native Range and Habitat

The roach inhabits temperate climates (Riehl and Baensch 1991). The species' native range includes regions of Europe and Asia. Within Europe, it is found north of the Pyrenees and Alps and eastward to the Ural River and Eya drainages (Caspian Sea basin) and within the Aegean Sea basin and watershed (Kottelat and Freyhof 2007). In Asia, the roach's native range extends from the Sea of Marmara basin and lower Sakarya Province (Turkey) to the Aral Sea basin and Siberia (Kottelat and Freyhof 2007).

This species often resides in nutrient-rich lakes, medium to large rivers, and backwaters. Within rivers, the roach is limited to areas with slow currents.

Nonnative Range and Habitat

This species has been introduced to several countries for recreational fishing

or as bait. Once introduced, the roach has moved into new water bodies within the same country (Rocabayera and Veiga 2012). In 1889, the roach was brought from England to Ireland for use as bait fish. Some of these fish accidentally escaped into the Cork Blackwater system. After this initial introduction, this fish species was deliberately stocked in nearby lakes. The roach has continued its expansion throughout Ireland watersheds, and by 2000, had invaded every major river system within Ireland (Rocabayera and Veiga 2012).

This species has been reported as invasive in north and central Italy, where it was introduced for recreational fishing (Rocabayera and Veiga 2012). The roach was also introduced to Madagascar, Morocco, Cyprus, Portugal, the Azores, Spain, and Australia (Rocabayera and Veiga 2012).

Biology

The roach has an average body length of 25 cm (9.8 in) and reported maximum length of 50 cm (19.7 in) (Rocabayera and Veiga 2012). The maximum published weight is 1.84 kg (4 lb) (Froese and Pauly 2014f).

The roach can live up to 14 years (Froese and Pauly 2014f). Male fish are sexually mature at 2 to 3 years and female fish at 3 to 4 years. A whole roach population typically spawns within 5 to 10 days, with each female producing 700 to 77,000 eggs (Rocabayera and Veiga 2012). Eggs hatch approximately 12 days later (Kottelat and Freyhoff 2007).

The roach has a general, omnivorous diet, including benthic invertebrates, zooplankton, plants, and detritus (Rocabayera and Veiga 2012). Of the European cyprinids (carps, minnows, and their relatives), the roach is one of the most efficient molluscivores (Winfield and Winfield 1994).

Parasitic infections, including worm cataracts (

Diplostomum spathaceum

), black spot disease (diplostomiasis), and tapeworm (

Ligula intestinalis

), have all been found associated with the roach (Rocabayera and Veiga 2012), as has the pathogen bacterium

Aeromonas salmonicida,

which causes furunculosis (skin ulcers) in several fish species (Wiklund and Dalsgaard 1998).

Invasiveness

The main issues associated with invasive roach populations include competition with native fish species, hybridization with native fish species, and altered ecosystem nutrient cycling (Rocabayera and Veiga 2012). The roach is a highly adaptive species and adapts to a different habitat or diet to avoid predation or competition (Winfield and Winfield 1994).

The roach also has a high reproductive potential and spawns earlier than some other native fish (Volta and Jepsen 2008, Rocabayera and Veiga 2012). This trait allows larvae to have a competitive edge over native fish larvae (Volta and Jepsen 2008).

The roach can hybridize with other cyprinids, including rudd (

Scardinius erythrophthalmus

) and bream (

Abramis brama

), in places where it has invaded. The new species (roach-rudd cross and roach-bream cross) then compete for food and habitat resources with both the native fish (rudd, bream) and invasive fish (roach) (Rocabayera and Veiga 2012).

Within nutrient-rich lakes or ponds, large populations of roach create adverse nutrient cycling. High numbers of roach consume large amounts of zooplankton, which results in algal blooms, increased turbidity, and changes in nutrient availability and cycling (Rocabayera and Veiga 2012).

Stone Moroko (Pseudorasbora parva)

The stone moroko was first described and cataloged by Temminick and Schlegel in 1846 and belongs to the order Cypriniformes and family Cyprinidae (ITIS 2014). Although the preferred common name is the stone moroko, this fish species is also called the topmouth gudgeon (Froese and Pauly 2014g).

Native Range and Habitat

The stone moroko inhabits a temperate climate (Baensch and Riehl 1993). Its native range is Asia, including southern and central Japan, Taiwan, Korea, China, and the Amur River basin. The stone moroko resides in freshwater lakes, ponds, rivers, streams, and irrigation canals (Copp 2007).

Nonnative Range and Habitat

The stone moroko was introduced to Romania in the early 1960s with a Chinese carp shipment (Copp

et al.

2010). By 2000, this fish species had invaded nearly every other European country and additional countries in Asia (Copp 2007). This species was primarily introduced unintentionally with fish shipped purposefully. Natural dispersal also occurred in most countries (Copp 2007).

Within Asia, the stone moroko has been introduced to Afghanistan, Armenia, Iran, Kazakhstan, Laos, Taiwan, Turkey, and Uzbekistan (Copp 2007). In Europe, this fish species' nonnative range includes Albania, Austria, Belgium, Bulgaria, Czech Republic, Denmark, France, Germany, Greece, Hungary, Italy, Lithuania, Moldova, Montenegro, Netherlands, Poland, Romania, Russia, Serbia, Slovakia, Spain, Sweden, Switzerland, Ukraine, and the United Kingdom (Copp 2007). The stone moroko has also been introduced to Algeria and Fiji (Copp 2007).

Biology

The stone moroko is a small fish with an average body length of 8 cm (3.1 in), maximum reported length of 11 cm (4.3 in) (Froese and Pauly 2014g), and average body mass of 17 to 19 grams (g; 0.04 lb) (Witkowski 2011). This fish species is grayish black with a lighter belly and sides. Juveniles have a dark stripe along the side that disappears with maturity (Witkowski 2011).

This fish species can live up to 5 years (Froese and Pauly 2014g). The stone moroko becomes sexually mature and begins spawning at 1 year (Witkowski 2011). Females release several dozen eggs per spawning event and spawn several times per year. The total number of eggs spawned per female ranges from a few hundred to a few thousand eggs (Witkowski 2011). Male fish aggressively guard eggs until hatching (Witkowski 2011).

The stone moroko maintains an omnivorous diet of small insects, fish, mollusks, planktonic crustaceans, fish eggs, algae (Froese and Pauly 2014g), and plants (Kottelat and Freyhof 2007).

The stone moroko is an unaffected carrier of the pathogenic parasite

Sphaerothecum destruens

(Gozlan

et al.

2005, Pinder

et al.

2005). This parasite is transferred to water from healthy stone morokos. Once in the water, this parasite has infected Chinook salmon (

Oncorhynchus tshawytscha

), Atlantic salmon, sunbleak (

Leucaspius delineatus

), and fathead minnows (

Pimephales promelas

) (Gozlan

et al.

2005).

Sphaerothecum destruens

infects the internal organs, resulting in spawning failure, organ failure, and death (Gozlan

et al.

2005).

Invasiveness

The stone moroko has proven to be a highly invasive fish, establishing invasive populations in nearly every European country over a 40-year span (Copp 2007, Copp

et al.

2010). This fish species has proven to be adaptive and tolerant of a variety of habitats, including those of poorer quality (Beyer

et al.

2007). This species' invasiveness is further aided by multiple spawning events and the guarding of eggs by the male until hatching (Kottelat and Freyhof 2007).

In many areas of introduction and establishment (for example, United

Kingdom, Italy, China, and Russia), the stone moroko has been linked to the decline of native freshwater fish populations (Copp 2007). The stone moroko has been found to dominate the fish community when it becomes established. Native fishes have exhibited decreased growth rate and reproduction, and they shifted their diet as a result of food competition (Britton

et al.

2010b).

Additionally, this species is a vector of

Sphaerothecum destruens,

which is a documented pathogen of salmonids native to the United States (Gozlan

et al.

2005, Gozlan

et al.

2009, Andreou

et al.

2011).

Sphaerothecum destruens

has caused mortalities in cultured North American salmon (Andreou

et al.

2011).

Nile Perch (Lates niloticus)

The Nile perch was first described and cataloged by Linnaeus in 1758 and is in the order Perciformes and family Centropomidae (ITIS 2014). Although its preferred common name is the Nile perch, it is also referred to as the African snook and Victoria perch (Witte 2013).

Native Range and Habitat

The Nile perch inhabits a tropical climate with an optimal water temperature of 28 °C (82 °F) and an upper lethal temperature of 38 °C (100 °F) (Kitchell

et al.

1997). The species' native distribution includes much of central, western, and eastern Africa. The species is common in the Nile, Chad, Senegal, Volta, and Zaire River basins and brackish Lake Mariout near Alexandria, Egypt, on the Mediterranean coast (Azeroual

et al.

2010, Witte 2013). Nile perch reside in brackish lakes and freshwater lakes, rivers, stream, reservoirs, and irrigation channels (Witte 2013).

Nonnative Range and Habitat

The Nile perch, which is not native to Lake Victoria in Africa, was first introduced to the lake in 1954 from nearby Lake Albert. This species was introduced on the Ugandan side and spread to the Kenyan side. A breeding population existed in the lake by 1962 (Witte 2013).

The Nile perch was also introduced to Lake Kyoga (1954 and 1955) to gauge the effects of Nile perch on fish populations similar to that of Lake Victoria. At the time of introduction, people were unaware that this species had already been introduced unofficially into Lake Victoria (Witte 2013). Additional introductions of Nile perch occurred in 1962 and 1963 in Kenyan and Ugandan waters to promote a commercial fishery. Since its initial introduction to Lakes Victoria and Kyoga, this fish species has been accidentally and deliberately introduced to many of the neighboring lakes and waterways (Witte 2013). The increase in Nile perch population was first noted in Kenyan waters in 1979, in Ugandan waters 2 to 3 years later, and in Tanzanian waters 4 to 5 years later (Witte 2013). There are currently only a few lakes in the area without a Nile perch population (Witte 2013).

The Nile perch was also introduced into Cuba for aquaculture and sport in 1982 and 1983 (Welcomme 1988), but we have no information on the subsequent status.

Nile perch were stocked in Texas waters in 1978, 1979, and 1984 (88, 14, and 26 fish respectively in Victor Braunig Lake); in 1981 (68,119 in Coleto Creek Reservoir); and in 1983 (1,310 in Fairfield Lake) (Fuller

et al.

1999, TPWD 2013a). These introductions were unsuccessful at establishing a self-sustaining population (Howells 1992, Howells and Garret 1992, Howells 2001). Although the fish did not establish, biologists in Texas and Florida recommended against stocking Nile perch because of its ability to tolerate cold winter temperatures in some local waters, tolerance of salt water, and ability to range widely in riverine habitats, as well as large size and predatory nature (Howells and Garret 1992). Today, Nile perch are a prohibited exotic species in Texas (TPWD 2013b, 2016).

Biology

The Nile perch has a perch-like body with an average body length of 1 meter (m) (3.3 feet (ft)), maximum length of 2 m (6.6 ft) (Ribbink 1987, Froese and Pauly 2014h), and maximum weight of 200 kg (441 lb) (Ribbink 1987). The Nile perch is gray-blue on the dorsal side with gray-silver along the flank and ventral side (Witte 2013).

The age of sexual maturity varies with habitat location. Most male fish become sexually mature before females (1 to 2 years versus 1 to 4 years of age) (Witte 2013). This species spawns throughout the year with increased spawning during the rainy season (Witte 2013). The Nile perch produce 3 million to 15 million eggs per breeding cycle (Asila and Ogari 1988). This high fecundity allows the Nile perch to quickly establish in new regions with favorable habitats (Ogutu-Ohwayo 1988). Additionally, the Nile perch's reproductive potential in introduced habitats is much greater than that of its prey, haplochromine cichlids (fish from the family Cichlidae), which have a reproductive rate of 13 to 33 eggs per breeding cycle (Goldschmidt and Witte 1990).

Nile perch less than 5 cm eat zooplankton (cladocerans and copepods) (Witte 2013). Juvenile Nile perch (35 to 75 cm long) feed on invertebrates, primarily aquatic insects, crustaceans, and mollusks (Ribbink 1987). Adult Nile perch are primarily piscivorous (fish eaters), but they also consume large crustaceans (

Caridina

and

Macrobrachium

shrimp) and insects (Witte 2013).

The Nile perch is host to a number of parasites capable of causing infections and diseases in other species, including sporozoa infections (

Hennegya

sp.),

Dolops

infestation,

Ergasilus

disease, gonad nematodosis disease (

Philometra

sp.), and

Macrogyrodactylus

and

Diplectanum

infestation (Paperna 1996, Froese and Pauly 2014i).

Invasiveness

The Nile perch has been listed as one of the 100 “World's Worst” Invaders by the Global Invasive Species Database (

http://www.issg.org

) (Snoeks 2010, ISSG 2015). During the 1950s and 1960s, this fish was introduced to several East African lakes for commercial fishing. This fish is now prevalent in Lake Victoria and constitutes more than 90 percent of demersal (bottom-dwelling) fish mass within this lake (Witte 2013). Since its introduction, native fish populations have declined or disappeared (Witte 2013). Approximately 200 native haplochromine cichlid species have become locally extinct due to predation and competition (Snoeks 2010, Witte 2013).

According to Gophen (2015), the Lake Victoria ecosystem was unique and comprised at least 400 endemic species of haplochromine fishes. Historically, the food web structure was naturally balanced, with short periods of anoxia in deep waters and dominance of diatomides algal species. During the 1980s, Nile perch became the dominant fish. The haplochromine species were depleted, and the whole ecosystem was modified. Algal assemblages were changed to Cyanobacteria; anoxia became more frequent and occurred in shallower waters. The effect of the Nile perch predation and its ecological implications in Lake Victoria is also confirmed by the elimination of planktivory by the haplochromine fishery. Consequently, this loss has resulted in significant shifts to the trophic-level structure and loss of biodiversity of this lake's ecosystem.

Amur Sleeper (Perccottus glenii)

The Amur sleeper was first described and cataloged by B.I. Dybowski in 1877, as part of the order Perciformes and family Odontobutidae (Bogutskaya and Naseka 2002, ITIS 2014). The Amur sleeper is the preferred common name of this freshwater fish, but this fish is also called the Chinese sleeper or rotan (Bogutskaya and Naseka 2002, Froese and Pauly 2014j). In this final rule, we will refer to the species as the Amur sleeper.

Native Range and Habitat

The Amur sleeper inhabits a temperate climate (Baensch and Riehl 2004). The species' native distribution includes much of the freshwater regions of northeastern China, northern North Korea, and eastern Russia (Reshetnikov and Schliewen 2013). Within China, this species is predominantly native to the lower to middle region of the Amur River watershed, including the Zeya, Sunguri, and Ussuri tributaries (Bogutskaya and Naseka 2002, Grabowska 2011) and Lake Khanka (Courtenay 2006). The Amur sleeper's range extends northward to the Tugur River (Siberia) (Grabowska 2011) and southward to the Sea of Japan (Bogutskaya and Naseka 2002, Grabowska 2011). To the west, the species does not occur in the Amur River upstream of Dzhalinda (Bogutskaya and Nasaka 2002).

The Amur sleeper inhabits freshwater lakes, ponds, canals, backwaters, flood plains, oxbow lakes, and marshes (Grabowska 2011). This fish is a poor swimmer, thriving in slow-moving waters with dense vegetation and muddy substrate and avoiding main river currents (Grabowska 2011). The Amur sleeper can live in poorly oxygenated water and can also survive in dried out or frozen water bodies by burrowing into and hibernating in the mud (Bogutskaya and Nasaka 2002, Grabowska 2011).

Although the Amur sleeper is a freshwater fish, there are limited reports of it appearing in saltwater environments (Bogutskaya and Naseka 2002). These reports seem to occur with flood events and are likely a consequence of these fish being carried downstream into these saltwater environments (Bogutskaya and Naseka 2002).

Nonnative Range and Habitat

This species' first known introduction was in western Russia. In 1912, Russian naturalist I.L. Zalivskii brought four Amur sleepers to the Lisiy Nos settlement (St. Petersburg, Russia) (Reshetnikov 2004, Grabowska 2011). These four fish were held in aquaria until 1916, when they were released into a pond, where they subsequently established a population before naturally dispersing into nearby waterbodies (Reshetnikov 2004, Grabowska 2011). In 1948, additional Amur sleepers were introduced to Moscow for use in ornamental ponds by members of an expedition (Bogutskaya and Naseka 2002, Reshetnikov 2004). These fish escaped the ponds into which they had been stocked and spread to nearby waters in the city of Moscow and Moscow Province (Reshetnikov 2004).

Additionally, Amur sleepers were introduced to new areas when they were unintentionally shipped to fish farms in fish stocks, such as silver carp (

Hypophthalmichthys molitrix

) and grass carp (

Ctenopharyngodon idella

). From these initial introductions, the Amur sleepers were able to expand from their native range through escape, release, and transfer between fish farms (Reshetnikov 2004). Additionally, Amur sleepers tolerate being transported and have been moved from one waterbody to another by anglers as bait (Reshetnikov 2004).

The Amur sleeper is an invasive species in western Russia and 16 additional countries: Mongolia, Belarus, Ukraine, Lithuania, Latvia, Estonia, Poland, Hungary, Romania, Slovakia, Serbia, Bulgaria, Moldova, Kazakhstan, Croatia, and recently Germany, where it is dispersing up the Danube River into western Europe (Reshetnikov and Schliewen 2013). The Amur sleeper is established within the Baikal, Baltic, and Volga water basins of Europe and Asia (Bogutskaya and Naseka 2002) and the Danube of Europe (Reshetnikov and Schliewen 2013). The occurrence of the Amur sleeper in a far-western region of Europe is highly troublesome because this invasive and hardy predator represents a major threat to European freshwater shallow lentic water-body ecosystems where the Amur sleeper is capable of depleting diversity in species of macroinvertebrates, amphibians, and fish (Reshetnikov and Schliewen 2013).

Biology

The Amur sleeper is a small- to medium-sized fish with a maximum body length of 25 cm (9.8 in) (Grabowska 2011) and weight of 250 g (0.6 lb) (Reshetnikov 2003). As with other fish species, both body length and weight vary with food supply, and larger Amur sleeper specimens have been reported from its nonnative range (Bogutskaya and Naseka 2002).

Body shape is fusiform with two dorsal fins, short pelvic fins, and rounded caudal fin (Grabowska 2011). The Amur sleeper has dark coloration of greenish olive, brownish gray, or dark green with dark spots and pale yellow to blue-green flecks (Grabowska 2011). Males are not easily discerned from females except during breeding season. Breeding males are darker (almost black) with bright blue-green spots (Grabowska 2011).

The Amur sleeper lifespan is from 7 to 10 years. Within native ranges, the fish rarely lives more than 4 years, whereas in nonnative ranges, the fish generally lives longer (Bogutskaya and Naseka 2002, Grabowska 2011). The fish reaches maturity between 2 and 3 years of age (Grabowska 2011) and has at least two spawning events per year.

The number of eggs per spawning event varies with female size. In the Wloclawski Reservoir, which is outside of the Amur sleeper's native range, the females produced an average of 7,766 eggs per female (range 1,963 to 23,479 eggs) (Grabowska

et al.

2011). Male Amur sleepers are active in prenatal care by guarding eggs and aggressively defending the nest (Bogutskaya and Naseka 2002, Grabowska

et al.

2011).

The Amur sleeper is a voracious, generalist predator that eats invertebrates (such as freshwater crayfish, shrimp, mollusks, and insects), amphibian tadpoles, and small fish (Bogutskaya and Naseka 2002). Reshetnikov (2003) found that the Amur sleeper significantly reduced species diversity of fishes and amphibians where it was introduced. In some small water bodies, Amur sleepers considerably decrease the number of species of aquatic macroinvertebrates, amphibian larvae, and fish species (Reshetnikov 2003, Pauly 2014, Kottelat and Freyhof 2007).

The predators of Amur sleepers include pike, perch, snakeheads (

Channa

spp.), and gulls (Laridae) (Bogutskaya and Naseka 2002). It is believed that this species is primarily controlled by snakeheads in their native range. Eggs and juveniles are fed on by a variety of insects (Bogutskaya and Naseka 2002).

The Amur sleeper reportedly has high parasitic burdens of more than 40 parasite species (Grabowska 2011). The host-specific parasites, including

Nippotaenia mogurndae

and

Gyrodactylus perccotti,

have been transported to new areas along with the introduced Amur sleeper (Košuthová

et al.

2004, Grabowska 2011). The cestode (tapeworm)

Nippotaenia mogurndae

was first reported in Europe in the River Latorica in east Slovakia in 1998, after

this same river was invaded by the Amur sleeper (Košuthová

et al.

2004). This parasite may be able to infect other fish species (Košuthová

et al.

2008). Thus, the potential for the Amur sleeper to function as a parasitic host could aid in the transmission of parasites to new environments and potentially to new species (Košuthová

et al.

2008, Košuthová

et al.

2009).

Invasiveness

The Amur sleeper is considered one of the most widespread, invasive fish in European freshwater ecosystems within the last several decades (Copp

et al.

2005a, Grabowska 2011, Reshetnikov and Ficetola 2011). Reshetnikov and Ficetola (2011) indicate that there are 13 expansion centers for this fish outside of its native range. Once this species has been introduced, it has proven to be capable of establishing sustainable populations (Reshetnikov 2004). Within the Vistula River (Poland), the Amur sleeper has averaged an annual expansion of its range by 88 kilometers (km) (54.5 miles (mi) per year) (Grabowska 2011). A recent study (Reshetnikov and Ficetola 2011) suggests many other regions of Europe and Asia, as well as the northeastern United States and southeastern Canada, have suitable climates for the Amur sleeper and are at risk for an invasion.

The Amur sleeper demonstrates many of the strongest traits for invasiveness: It consumes a highly varied diet, is fast growing with a high reproductive potential, easily adapts to different environments, and has an expansive native range and proven history of increasing its nonnative range by itself and through human-mediated activities (Grabowska 2011). Where it is invasive, the Amur sleeper competes with native species for similar habitat and diet resources (Reshetnikov 2003, Kottelat and Freyhof 2007). This fish has also been associated with the decline in populations of the European mudminnow (

Umbra krameri

), crucian carp, and belica (

Leucaspius delineates

) (Grabowska 2011). This species hosts parasites that may be transmitted to native fish species when introduced outside of its native range (Košuthová

et al.

2008, Košuthová

et al.

2009)

European Perch (

Perca fluviatilis

)

The European perch was first described and cataloged by Linnaeus in 1758, and is part of the order Perciformes and family Percidae (ITIS 2014). European perch is the preferred common name, but this species may also be referred to as the Eurasian perch or redfin perch (Allen 2004, Froese and Pauly 2014).

Native Range and Habitat

The European perch inhabits a temperate climate (Riehl and Baensch 1991, Froese and Pauly 2014). This species' native range extends throughout Europe and regions of Asia, including Afghanistan, Armenia, Azerbaijan, Georgia, Iran, Kazakhstan, Mongolia, Turkey, and Uzbekistan (Froese and Pauly 2014k). The fish resides in a range of habitats that includes estuaries and freshwater lakes, ponds, rivers, and streams (Froese and Pauly 2014k).

Nonnative Range and Habitat

The European perch has been intentionally introduced to several countries for recreational fishing, including Ireland (in the 1700s), Australia (in 1862), South Africa (in 1915), Morocco (in 1939), and Cyprus (in 1971) (FAO 2014, Froese and Pauly 2014k). This species was introduced intentionally to Turkey for aquaculture (FAO 2004) and unintentionally to Algeria when it was included in the transport water with carp intentionally brought into the country (Kara 2012, Froese and Pauly 2014k). European perch have also been introduced to China (in the 1970s), Italy (in 1860), New Zealand (in 1867), and Spain (no date) for unknown reasons (FAO 2014). In Australia, this species was first introduced as an effort to introduce wildlife familiar to European colonizers (Arthington and McKenzie 1997). The European perch was first introduced to Tasmania in 1862, Victoria in 1868, and to southwest Western Australia in 1892 and the early 1900s (Arthington and McKenzie 1997). This species has now invaded western Victoria, New South Wales, Tasmania, Western Australia, and South Australian Gulf Coast (NSW DPI 2013). In the 1980s, the European perch invaded the Murray River in southwestern Australia (Hutchison and Armstrong 1993).

Biology

The European perch has an average body length of 25 cm (10 in) with a maximum length of 60 cm (24 in) (Kottelat and Freyhof 2007, Froese and Pauly 2014k) and an average body weight of 1.2 kg (2.6 lb) with a maximum weight of 4.75 kg (10.5 lb) (Froese and Pauly 2014k). European perch color varies with habitat. Fish in well-lit shallow habitats tend to be darker, whereas fish residing in poorly lit areas tend to be lighter. These fish may also absorb carotenoids (nutrients that cause color) from their diet (crustaceans), resulting in reddish-yellow color (Allen 2004). Male fish are not easily externally differentiated from female fish (Allen 2004).

The European perch lives up to 22 years (Froese and Pauly 2014k), although the average is 6 years (Kottelat and Freyhof 2007). This fish may participate in short migrations prior to spawning in February through July, depending on latitude and altitude (Kottelat and Freyhof 2007). Female fish are sexually mature at 2 to 4 years and males at 1 to 2 years (Kottelat and Freyhof 2007).

The European perch is a generalist predator with a diet of zooplankton, macroinvertebrates (such as copepods and crustaceans), and small fish (Kottelat and Freyhof 2007, Froese and Pauly 2014k).

The European perch can also carry the OIE-notifiable disease epizootic haematopoietic necrosis (EHN) virus (NSW DPI 2013). Several native Australian fish (including the silver perch (

Bidyanus bidyanus

) and Murray cod (

Maccullochella peelii

)) are extremely susceptible to the virus and have had significant population declines over the past decades with the continued invasion of European perch (NSW DPI 2013).

Invasiveness

The European perch has been introduced to many new regions through fish stocking for recreational use. The nonnative range has also expanded as the fish has swum to new areas through connecting waterbodies (lakes, river, and streams within the same watershed). In New South Wales, Australia, these fish are a serious pest and are listed as Class 1 noxious species (NSW DPI 2013). These predatory fish have been blamed for the local extirpation of the mudminnow (

Galaxiella munda

) (Moore 2008, ISSG 2010) and depleted populations of native invertebrates and fish (Moore 2008). This species reportedly consumed 20,000 rainbow trout (

Oncorhynchus mykiss

) fry from an Australian reservoir in less than 3 days (NSW DPI 2013). The introduction of these fish in New Zealand and China has severely altered native freshwater communities (Closs

et al.

2003). European perch form dense populations, forcing them to compete amongst each other for a reduced food supply. This competition results in stunted fish that are less appealing to the recreational fishery (NSW DPI 2013).

Zander (

Sander lucioperca

)

The zander was first described and catalogued by Linnaeus in 1758, and belongs to the order Perciformes and family Percidae (ITIS 2014). Although

its preferred common name in the United States is the zander, this fish species is also called the pike-perch and European walleye (Godard and Copp 2011, Froese and Pauly 2014l).

Native Range and Habitat

The zander's native range includes the Caspian Sea, Baltic Sea, Black Sea, Aral Sea, North Sea, and Aegean Sea basins. In Asia, this fish is native to Afghanistan, Armenia, Azerbaijan, Georgia, Iran, Kazakhstan, and Uzbekistan. In Europe, the zander is native to much of eastern Europe (Albania, Austria, Czech Republic, Estonia, Germany, Greece, Hungary, Latvia, Lithuania, Moldova, Poland, Romania, Russia, Serbia, Slovakia, Ukraine, and Serbia and Montenegro) and the Scandinavian Peninsula (Finland, Norway, and Sweden) (Godard and Copp 2011, Froese and Pauly 2014l). The northernmost records of native populations are in Finland up to 64 °N (Larsen and Berg 2014).

The zander resides in brackish coastal estuaries and freshwater rivers, lakes, and reservoirs. The species prefers turbid, slightly eutrophic waters with high dissolved oxygen concentrations (Godard and Copp 2011). The zander can survive in salinities up to 20 parts per thousand (ppt), but prefers environments with salinities less than 12 ppt and requires less than 3 ppt for reproduction (Larsen and Berg 2014).

Nonnative Range and Habitat

The zander has been repeatedly introduced outside of its native range for recreational fishing and aquaculture and also to control cyprinids (Godard and Copp 2011, Larsen and Berg 2014). This species has been introduced to much of Europe, parts of Asia (China, Kyrgyzstan, and Turkey), and northern Africa (Algeria, Morocco, and Tunisia). Within Europe, the zander has been introduced to Belgium, Bulgaria, Croatia, Cyprus, Denmark, France, Italy, the Netherlands, Portugal, the Azores, Slovenia, Spain, Switzerland, and the United Kingdom (Godard and Copp 2011, Froese and Pauly 2014l). In Denmark, although the zander is native, stocking is not permitted to prevent the species from being introduced into lakes and rivers where it is not presently found and where introduction is not desirable (Larsen and Berg 2014).

The zander has been previously introduced to the United States. Juvenile zanders were stocked into Spiritwood Lake (North Dakota) in 1989 for recreational fishing (Fuller

et al.

1999, Fuller 2009, USGS NAS 2014). Although previous reports indicated that zanders did not become established in Spiritwood Lake, there have been documented reports of captured juvenile zanders from this lake (Fuller 2009). In 2009, the North Dakota Game and Fish Department reported a small, established population of zanders within Spiritwood Lake (Fuller 2009), and a zander caught in 2013 was considered the State record (North Dakota Game and Fish 2013).

Biology

The zander has an average body length of 50 cm (1.6 ft) and maximum body length of 100 cm (3.3 ft). The maximum published weight is 20 kg (44 lb) (Froese and Pauly 2014l). The zander has a long, slender body with yellow-gray fins and dark bands running from the back down each side (Godard and Copp 2011).

The zander's age expectancy is inversely correlated to its body growth rate. Slower-growing zanders may live up to 20 to 24 years, whereas faster-growing fish may live only 8 to 9 years (Godard and Copp 2011). Female zanders typically spawn in April and May and produce approximately 150 to 400 eggs per gram of body mass. After spawning, male zanders protect the nest and fan the eggs with their tails (Godard and Copp 2011).

The zander is piscivorous, and its diet includes smelt (

Osmerus eperlanus

), ruffe (

Gymnocephalus cernuus

), European perch, vendace (

Coregonus albula

), roach, and other zanders (Kangur and Kangur 1998).

Several studies have found that zanders can be hosts for multiple parasites (Godard and Copp 2011). The nematode

Anisakis,

which is known to infect humans through fish consumption, has been documented in the zander (Eslami and Mokhayer 1977, Eslami

et al.

2011). A study in the Polish section of Vistula Lagoon found 26 species of parasites associated with the zander, which was more than any of the other 15 fish species studied (Rolbiecki 2002, 2006).

Invasiveness

The zander has been intentionally introduced numerous times for aquaculture, recreational fishing, and occasionally for biomanipulation to remove unwanted cyprinids (Godard and Copp 2011). Biomanipulation is the management of an ecosystem by adding or removing species. The zander migrates for spawning, which further expands its invasive range. It is a predatory fish that is well-adapted to turbid water and low-light habitats (Sandström and Karås 2002). The zander competes with and preys on native fish. The zander is also a vector for the trematode

Bucephalus polymorphus,

which has been linked to a decrease in native French cyprinid populations (Kvach and Mierzejewska 2011).

Wels Catfish (Silurus glanis)

The wels catfish was first described and cataloged by Linnaeus in 1758, and belongs to the order Siluriformes and family Siluridae (ITIS 2014). The preferred common name is the wels catfish, but this fish is also called the Danube catfish, European catfish, and sheatfish (Rees 2012, Froese and Pauly 2014m).

Native Range and Habitat

The wels catfish inhabits a temperate climate (Baensch and Riehl 2004). The species is native to eastern Europe and western Asia, including the North Sea, Baltic Sea, Black Sea, Caspian Sea, and Aral Sea basins (Rees 2012, Froese and Pauly 2014m). The species resides in slow-moving rivers, backwaters, shallow floodplain channels, and heavily vegetated lakes (Kottelat and Freyhof 2007). The wels catfish has also been found in brackish water of the Baltic and Black Seas (Froese and Pauly 2014m). The species is a demersal (bottom-dwelling) species that prefers residing in crevices and root habitats (Rees 2012).

Nonnative Range and Habitat

The wels catfish was introduced to the United Kingdom and western Europe during the 19th century. The species was first introduced to England in 1880 for recreational fishing at the private Bedford manor estate of Woburn Abbey. Since then, wels catfish have been stocked both legally and illegally into many lakes and are now widely distributed throughout the United Kingdom (Rees 2012). This species was introduced to Spain, Italy, and France for recreational fishing and aquaculture (Rees 2012). Wels catfish were introduced to the Netherlands as a substitute predator to control cyprinid fish populations (De Groot 1985) after the native pike were overfished. The wels catfish has also been introduced to Algeria, Belgium, Bosnia-Hercegovina, China, Croatia, Cyprus, Denmark, Finland, Portugal, Syria, and Tunisia, although they are not known to be established in Algeria or Cyprus (Rees 2012).

Biology

The wels catfish commonly grows to 3 m (9.8 ft) in body length with a maximum length of 5 m (16.4 ft) and is Europe's largest freshwater fish (Rees 2012). The maximum published weight is 306 kg (675 lb) (Rees 2012).

This species has a strong, elongated, scaleless, mucus-covered body with a flattened tail. The body color is variable but is generally mottled with dark greenish-black and creamy-yellow sides. Wels catfishes possess six barbels; two long ones on each side of the mouth, and four shorter ones under the jaw (Rees 2012).

Although the maximum reported age is 80 years (Kottelat and Freyhof 2007), the average lifespan of a wels catfish is 15 to 30 years. This species becomes sexually mature at 3 to 4 years of age. Nocturnal spawning occurs annually and aligns with optimal temperature and day length between April and August (Kottelat and Freyhof 2007, Rees 2012). The number of eggs produced per female, per year is highly variable, and depends on age, size, geographic location, and other factors. Studies in Asia have documented egg production of a range of approximately 8,000 to 467,000 eggs with the maximum reported being 700,000 eggs (Copp

et al.

2009). Male fish will guard the nest, repeatedly fanning their tails to ensure proper ventilation until the eggs hatch 2 to 10 days later (Copp

et al.

2009). Young catfish develop quickly and, on average, achieve a 38- to 48-cm (15- to 19-in) total length within their first year (Copp

et al.

2009).

This species is primarily nocturnal and will exhibit territorial behavior (Copp

et al.

2009). The wels catfish is a solitary ambush predator but is also an opportunistic scavenger of dead fish (Copp

et al.

2009). Juvenile catfish typically eat invertebrates. Adult catfish are generalist predators with a diet that includes fish (at least 55 species), crayfish, small mammals (such as rodents), and waterfowl (Copp

et al.

2009, Rees 2012). Wels catfish have been observed beaching themselves to prey on land birds located on river banks (Cucherousset 2012).

Juvenile wels catfish can carry the highly infectious SVC (Hickley and Chare 2004). This disease is recognized worldwide and is classified as a notifiable animal disease by the World Organisation for Animal Health (OIE 2014). The wels catfish is also a host to at least 52 parasites, including:

Trichodina siluri, Myxobolus miyarii,

Leptorhynchoides plagicephalus

and

Pseudotracheliastes stellifer,

all of which may be detrimental to native fish survival (Copp

et al.

2009).

Invasiveness

The wels catfish is a habitat-generalist that tolerates poorly oxygenated waters and has been repeatedly introduced to the United Kingdom and western Europe for aquaculture, research, pest control, and recreational fishing (Rees 2012). Although this species has been intentionally introduced for aquaculture and fishing, it has also expanded its nonnative range by escaping from breeding and stocking facilities (Rees 2012). This species is tolerant of a variety of warm-water habitats, including those with low dissolved oxygen levels. The invasive success of the wels catfish will likely be further enhanced with the predicted increase in water temperature with climate change (2 to 3 °C by 2050) (Rahel and Olden 2008, Britton

et al.

2010a).

The major risks associated with invasive wels catfish to the native fish population include disease transmission (SVC) and competition for habitat and prey species (Rees 2012). This fish species also excretes large amounts of phosphorus and nitrogen (estimated 83- to 286-fold and 17- to 56-fold, respectively) (Boulêtreau

et al.

2011) into the ecosystem and consequently greatly disrupts nutrient cycling and transport (Schaus

et al.

1997, McIntyre

et al.

2008, Boulêtreau

et al.

2011). Because of their large size, multiple wels catfish in one location magnify these effects and can greatly increase algae and plant growth (Boulêtreau

et al.

2011), which reduces water quality.

Common Yabby (Cherax destructor)

Unlike the 10 fish in this rule, the yabby is a crayfish. Crayfish are invertebrates with hard shells. They can live and breathe underwater, and they crawl along the substrate on four pairs of walking legs (Holdich and Reeve 1988); the pincers are considered another pair of walking legs. The common yabby was first described and cataloged by Clark in 1936 and belongs to the phylum Arthropoda, order Decapoda, and family Parastacidae (ITIS 2014). This freshwater crustacean may also be called the yabby or the common crayfish. The term “yabby” is also commonly used for crayfish in Australia.

Native Range and Habitat

The common yabby is native to eastern Australia and extends from South Australia, northward to southern parts of the Northern Territory, and eastward to the Great Dividing Range (Eastern Highlands) (Souty-Grosset

et al.

2006, Gherardi 2012).

The common yabby inhabits temperate and tropical climates. In aquaculture, the yabby tolerates the wide range of water temperatures from 1 to 35 °C (34 to 95 °F), with an optimal water temperature range of 20 to 25 °C (68 to 77 °F) (Withnall 2000). Growth halts below 15 °C (59 °F) and above 34 °C (93 °F), partial hibernation (decreased metabolism and feeding) occurs below 16 °C (61 °F), and death occurs when temperatures rise above 36 °C (97 °F) (Gherardi 2012). The common yabby can also survive drought for several years by sealing itself in a deep burrow (burrows well over 5 m; 16.4 ft have been found) and aestivating (the crayfish's respiration, pulse, and digestion nearly cease) (NSW DPI 2015).

This species can tolerate a wide range of dissolved oxygen concentrations and salinities (Mills and Geddes 1980) but prefers salinities less than 8 ppt (Withnall 2000, Gherardi 2012). Growth ceases at salinities above 8 ppt (Withnall 2000). This correlates with Beatty's (2005) study where all yabbies found in waters greater than 20 ppt were dead. Yabbies have been found in ponds where the dissolved oxygen was below 1 percent saturation (NSW DPI 2015).

The common yabby resides in a variety of habitats, including desert mound springs, alpine streams, subtropical creeks, rivers, billabongs (small lake, oxbow lake), temporary lakes, swamps, farm dams, and irrigation channels (Gherardi 2012). The yabby is found in mildly turbid waters and muddy or silted bottoms. The common yabby digs burrows that connect to waterways (Withnall 2000). Burrowing can result in unstable and collapsed banks (Gherardi 2012).

Nonnative Range and Habitat

The common yabby is commercially valuable and is frequently imported by countries for aquaculture, aquariums, and research (Gherardi 2012); it is raised in aquaculture as food for humans (NSW DPI 2015). This species has spread throughout Australia, and its nonnative range extends to New South Wales east of the Great Dividing Range, Western Australia, and Tasmania. This crayfish species was introduced to Western Australia in 1932 for commercial aquaculture from where it escaped and established in rivers and irrigation dams (Souty-Grosset

et al.

2006). Outside of Australia, this species has been introduced into Italy and Spain where it has become established (Gherardi 2012). The common yabby has been introduced to China, South Africa, and Zambia for aquaculture (Gherardi 2012) but has not become established in the wild in those countries. The first European introduction occurred in 1983, when common yabbies were transferred from a California farm to a pond in Girona, Catalonia, Spain (Souty-Grosset

et al.

2006). This crayfish species became established in Zaragoza Province, Spain, after being introduced

in 1984 or 1985 (Souty-Grosset

et al.

2006).

Biology

The common yabby has been described as a “baby lobster” because of its relatively large body size for a crayfish and because of its unusually large claws. Yabbies have a total body length up to 15 cm (6 in) with a smooth external carapace (exoskeleton) (Souty-Grosset

et al.

2006, Gherardi 2012). Body color can vary with geographic location, season, and water conditions (Withnall 2000). Most captive-cultured yabbies are blue-gray, whereas wild yabbies may be green-beige to black (Souty-Grosset

et al.

2006, Withnall 2000). Yabbies in the aquarium trade can be blue or white and go by the names blue knight and white ghost (LiveAquaria.com 2014a, b).

Most common yabbies live 3 years with some living up to 6 years (Souty-Grosset

et al.

2006, Gherardi 2012). Females can be distinguished from males by the presence of gonopores at the base of the third pair of walking legs; while males have papillae at the base of the fifth pair of walking legs (Gherardi 2012). The female yabby becomes sexually mature before it is 1 year old (Gherardi 2012). Spawning is dependent on day length and water temperatures. When water temperatures rise above 15 °C (59 °F), the common yabby will spawn from early spring to mid-summer. When the water temperature is consistently between 18 and 20 °C (64 to 68 °F) with daylight of more than 14 hours, the yabby will spawn up to five times a year (Gherardi 2012). Young females produce 100 to 300 eggs per spawning event, while older (larger) females can produce up to 1,000 eggs (Withnall 2000). Incubation is also dependent on water temperature and typically lasts 19 to 40 days (Withnall 2000).

The common yabby grows through molting, which is shedding of the old carapace and then growing a new one (Withnall 2000). A juvenile yabby will molt every few days, whereas, an adult yabby may molt only annually or semiannually (Withnall 2000).

The common yabby is an opportunistic omnivore with a carnivorous summer diet and herbivorous winter diet (Beatty 2005). The diet includes fish (

Gambusia holbrooki

), plant material, detritus, and zooplankton. The yabby is also cannibalistic, especially where space and food are limited (Gherardi 2012).

The common yabby is affected by at least ten parasites (Jones and Lawrence 2001), including the crayfish plague (caused by

Aphanomyces astaci

), burn spot disease,

Psorospermium

sp. (a parasite), and thelohaniasis (Jones and Lawrence 2001, Souty-Grosset

et al.

2006, Gherardi 2012). The crayfish plague is an OIE-reportable disease. Twenty-three bacteria species have been found in the yabby as well (Jones and Lawrence 2001).

Invasiveness

The common yabby has a quick growth and maturity rate, high reproductive potential, and generalist diet. These attributes, in addition to the species' tolerance for a wide range of freshwater habitats, make the common yabby an efficient invasive species. Additionally, the invasive range of the common yabby is expected to expand with climate change (Gherardi 2012). Yabbies can also live on land and travel long distances by walking between water bodies (Gherardi 2011).

The common yabby may reduce biodiversity through competition and predation with native species. In its nonnative range, the common yabby has proven to out-compete native crayfish species for food and habitat (Beatty 2006, Gherardi 2012). Native freshwater crayfish species are also at risk from parasitic infections from the common yabby (Gherardi 2012).

Summary of the Presence of the 11 Species in the United States

Only one of the 11 species, the zander, is known to be present in the wild within the United States. There has been a small established population of zander within Spiritwood Lake (North Dakota) since 1989. Crucian carp were reportedly introduced to Chicago lakes and lagoons during the early 1900s. Additionally, Nile perch were introduced to Texas reservoirs between 1978 and 1985. However, neither the crucian carp nor the Nile perch established populations, and these two species are no longer present in the wild in U.S. waters. Although these species are not yet present in the United States (except for one species in one lake), all 11 species have a high climate match in parts of the United States and have been introduced, become established, spread, and been documented as causing harm in countries outside of their native ranges in habitats and ecosystems similar to those found in the United States. Acting now to prohibit both their importation and interstate transportation and thereby prevent the species' likely introduction, establishment, and spread in the wild and associated harm to the interests of agriculture or to wildlife or wildlife resources of the United States is critical.

Rapid Screening

The first step that the Service performed in selecting species to evaluate for listing as injurious was to prepare a rapid screen to assess which species out of thousands of foreign species not yet found in the United States should be categorized as high-risk of invasiveness. We compiled the information in Ecological Risk Screening Summaries (ERSS) for each species to determine the Overall Risk Assessment of each species.

The Overall Risk Assessment incorporates scores for the history of invasiveness, climate match between the species' range (native and invaded ranges) and the United States, and certainty of assessment.

The climate match analysis (Australian Bureau of Rural Sciences 2010) incorporates 16 climate variables (eight for rainfall and eight for temperature) to calculate climate scores that can be used to calculate a Climate 6 ratio. The Climate 6 score (or ratio) is determined by this formula: (Sum of the Counts for Climate Match Scores 6-10)/(Sum of all Climate Match Scores). This ratio was shown to be the best predictor of success of introduction of exotic freshwater fish (Bomford 2008). Using the Climate 6 ratio, species can be categorized as having a low (0.000 to 0.005), medium (greater than 0.005 to less than 0.103), or high (greater than 0.103) climate match (Bomford 2008; USFWS 2013b).

The climate match score is a calculation that ranges from 0 to 10. It compares the 16 climate variables as one point (source climate station) to another point (target station). The equation calculates a figurative “distance” between every source and target station, then selects the highest score (best match and closest “distance”). This distance is then normalized on a score from 0 to 10 to make it easier to understand and to calculate ratios. The 16 climate parameters used to estimate the extent of climatically matched habitat in the CLIMATE program are in Table 1 (Bomford

et al.

2010).

Table 1—The Climate Parameters Used in the CLIMATE Program

Temperature

parameters

(°C)

Rainfall parameters

(mm)

Mean annual

Mean annual.

Minimum of coolest month

Mean of wettest month.

Maximum of warmest month

Mean of driest month.

Average range

Mean monthly coefficient of variation.

Mean of coolest quarter

Mean of coolest quarter.

Mean of warmest quarter

Mean of warmest quarter.

Mean of wettest quarter

Mean of wettest quarter.

Mean of driest quarter

Mean of driest quarter.

We use Climate 6 scores because that system was peer reviewed (Bomford 2008). In Bomford's seminal risk assessment manual, she stated, “The generic model is based on Climate 6 (as opposed to Climate 5, 7 or 8), since Climate 6 was shown to be the best predictor of success of introduction,” referring to exotic freshwater fish. We believe that the categorical system provided by generating and using the Climate 6 Ratio is effective for our current needs. For more information on how the climate match scores are derived, please see the revised Standard Operating Procedures (USFWS 2016).

As explained in the proposed rule, the Service expanded the source ranges (native and nonnative distribution) of several species for the climate match from those listed in the ERSSs. The revised source ranges included additional locations referenced in FishBase (Froese and Pauly 2014), the CABI ISC, and the

Handbook of European Freshwater Fishes

(Kottelat and Freyhof 2007). Additional source points were also specifically selected for the stone moroko's distribution within the United Kingdom (Pinder

et al.

2005). There were no revisions to the climate match for the Nile perch, Amur sleeper, or common yabby. The target range for the climate match included the States, District of Columbia, Guam, Puerto Rico, and the U.S. Virgin Islands.

The ERSS process was peer-reviewed in 2013 per OMB guidelines (OMB 2004). More information on the ERSS process and its peer review is posted online at

http://www.fws.gov/injuriouswildlife/Injurious_prevention.html, http://www.fws.gov/science/pdf/ERSS-Process-Peer-Review-Agenda-12-19-12.pdf,

and

http://www.fws.gov/science/pdf/ERSS-Peer-Review-Response-report.pdf.

The Overall Risk Assessment was found to be high for all 11 species. All 11 species have a high risk for history of invasiveness. Overall climate match to the United States ranged from medium for the Nile perch to high for the remaining nine fish and one crayfish species. The certainty of assessment (with sufficient and reliable information) was high for all species.

Injurious Wildlife Evaluation Criteria

Once we determined that all 11 species were good candidates for further and more in-depth evaluation because of their overall invasive risk, we used the criteria below to evaluate whether each of these species qualifies as injurious under the Act. The analysis using these criteria serve as a general basis for the Service's injurious wildlife listing decisions. Biologists within the Service evaluate both the factors that contribute to and the factors that reduce the likelihood of injuriousness:

(1) Factors that contribute to being considered injurious:

• The likelihood of release or escape;

• Potential to survive, become established, and spread;

• Impacts on wildlife resources or ecosystems through hybridization and competition for food and habitats, habitat degradation and destruction, predation, and pathogen transfer;

• Impacts to endangered and threatened species and their habitats;

• Impacts to human beings, forestry, horticulture, and agriculture; and

• Wildlife or habitat damages that may occur from control measures.

(2) Factors that reduce the likelihood of the species being considered as injurious:

• Ability to prevent escape and establishment;

• Potential to eradicate or manage established populations (for example, making organisms sterile);

• Ability to rehabilitate disturbed ecosystems;

• Ability to prevent or control the spread of pathogens or parasites; and

• Any potential ecological benefits to introduction.

For this final rule, a hybrid is defined as any progeny (offspring) from any cross involving a parent from 1 of the 11 species. These progeny would likely have the same or similar biological characteristics of the parent species (Ellstrand and Schierenbeck 2000, Mallet 2007), which, according to our analysis, would indicate that they are injurious to the interests of agriculture, or to wildlife or wildlife resources of the United States.

Factors That Contribute to Injuriousness for Crucian Carp

Current Nonnative Occurrences

This species is not currently found within the United States. The crucian carp has been introduced and become established in Croatia, Greece, France, Italy, and England (Crivelli 1995, Kottelat and Freyhof 2007).

Potential Introduction and Spread

Potential pathways of introduction into the United States include stocking for recreational fishing and through misidentified shipments of ornamental fish (Wheeler 2000, Hickley and Chare 2004, Innal and Erk'ahan 2006, Sayer

et al.

2011). Additionally, crucian carp may be misidentified as other carp species, such as the Prussian carp or common carp, and thus they are likely underreported (Godard and Copp 2012).

The crucian carp prefers a temperate climate (as found in much of the United States) and tolerates high summer air temperatures (up to 35 °C (95 °F)) and can survive in poorly oxygenated waters (Godard and Copp 2012). The crucian carp has an overall high climate match with a Climate 6 ratio of 0.355. This species has a high climate match throughout much of the Great Lakes region, southeastern United States, and southern Alaska and Hawaii. Low matches occur in the desert Southwest.

If introduced, the crucian carp is likely to spread and become established in the wild due to its ability to be a habitat and diet generalist and adapt to new environments, its long lifespan (maximum 10 years), and its ability to establish outside of the native range.

Potential Impacts to Native Species (including Threatened and Endangered Species)

As mentioned previously, the crucian carp can compete with native fish species, alter the health of freshwater habitats, hybridize with other invasive and injurious carp species, and serve as a vector of the OIE-reportable fish disease SVC (Ahne

et al.

2002, Godard and Copp 2012). The introduction of crucian carp to the United States could result in increased competition with native fish species for food resources (Welcomme 1988). The crucian carp consumes a variety of food resources, including plankton, benthic invertebrates, plant materials, and detritus (Kottelat and Freyhof 2007). With this varied diet, crucian carp would directly compete with numerous native species.

The crucian carp has a broad climate match throughout the country, and thus its introduction and establishment could further stress the populations of numerous endangered and threatened amphibian and fish species through competition for food resources.

The ability of crucian carp to hybridize with other species of

Cyprinidae (including common carp) may exacerbate competition over limited food resources and ecosystem changes and, thus, further challenge native species (including native threatened or endangered fish species).

Crucian carp harbor the fish disease SVC and additional parasitic infections. Although SVC also infects other carp species, the virus causing this disease can also be transmitted through the water column to native fish species causing fish mortalities. Mortality rates from SVC have been documented up to 70 percent among juvenile fish and 30 percent among adult fish (Ahne

et al.

2002). Therefore, as a vector of SVC, this fish species may also be responsible for reduced wildlife diversity. Crucian carp may outcompete native fish species, thus replacing them in the trophic scheme. Large populations of crucian carp can result in considerable predation on aquatic plants and invertebrates. Changes in ecosystem cycling and wildlife diversity may have negative effects on the aesthetic, recreational, and economic benefits of the environment.

Potential Impacts to Humans

We have no reports of the crucian carp being directly harmful to humans.

Potential Impacts to Agriculture

The introduction of crucian carp is likely to affect agriculture by contaminating commercial aquaculture. This fish species can harbor SVC, which can infect numerous fish species, including common carp, koi (

C. carpio

), crucian carp, bighead carp

(Hypophthalmichthys nobilis

), silver carp, and grass carp (Ahne

et al.

2002). This disease can cause serious fish mortalities, and thus can detrimentally affect the productivity of several species in commercial aquaculture facilities, including grass carp, goldfish, koi, fathead minnows (

Pimephales promelas

), and golden shiner (

Notemigonus crysoleucas

) (Ahne

et al.

2002, Goodwin 2002).

Factors That Reduce or Remove Injuriousness for Crucian Carp

Control

Lab experiments indicate that the piscicide rotenone (a commonly used natural fish poison) could be used to control a crucian carp population (Ling 2003). However, rotenone is not target-specific (Wynne and Masser 2010). Depending on the applied concentration, rotenone kills other aquatic species in the water body. Some fish species are more susceptible than others, and the use of this piscicide may kill native species. Control measures that would harm other wildlife are not recommended as mitigation plans to reduce the injurious characteristics of this species and, therefore, do not meet control measures under the Injurious Wildlife Evaluation Criteria.

No other control methods are known for the crucian carp, but several other control methods are currently being used or are in development for introduced and invasive carp species of other genera. For example, the U.S. Geological Survey (USGS) is developing a method to orally deliver a piscicide (Micromatrix) specifically to invasive bighead carp and silver carp (Luoma 2012). This developmental control measure is expensive and not guaranteed to prove effective for any carps.

Potential Ecological Benefits for Introduction

We are not aware of any documented ecological benefits for the introduction of crucian carp.

Factors That Contribute to Injuriousness for Eurasian Minnow

Current Nonnative Occurrences

This species is not currently found within the United States. The Eurasian minnow was introduced to new waterways in its native range of Europe and Asia (Sandlund 2008). This fish species also has been introduced outside of its native range to new locations within Norway (Sandlund 2008, Hesthagen and Sandlund 2010).

Potential Introduction and Spread

Likely pathways of introduction include release or escape when used as live bait, unintentional inclusion in the transport water of intentionally stocked fish (often with salmonids), and intentional introduction for vector (insect) management (Sandlund 2008). Once introduced, this species can spread and establish in nearby waterways.

The Eurasian minnow prefers a temperate climate (Froese and Pauly 2014e). This minnow is capable of establishing in a variety of aquatic ecosystems ranging from freshwater to brackish water (Sandlund 2008). The Eurasian minnow has an overall high climate match to the United States with a Climate 6 ratio of 0.397. The highest climate matches are in the northern States, including Alaska. The lowest climate matches are in the Southeast and Southwest.

If introduced to the United States, the Eurasian minnow is highly likely to spread and become established in the wild due to this species' traits as a habitat generalist and generalist predator, with adaptability to new environments, high reproductive potential, long lifespan, extraordinary mobility, social nature, and proven invasiveness outside of the species' native range.

Potential Impacts to Native Species (including Endangered and Threatened Species)

Introduction of the Eurasian minnow can affect native species through several mechanisms, including competition over resources, predation, and parasite transmission. Introduced Eurasian minnows have a more serious effect in waters with fewer species than those waters with a more developed, complex fish community (Museth

et al.

2007). In Norway, dense populations of the Eurasian minnow have resulted in an average 35 percent reduction in recruitment and growth rates in native brown trout (Museth

et al.

2007). In the United States, introduced Eurasian minnow populations would likely compete with and adversely affect Atlantic salmon, State-managed brown trout, and other salmonid species.

Eurasian minnow introductions have also disturbed freshwater benthic invertebrate communities (Næstad and Brittain 2010). Increased predation by Eurasian minnows has led to shifts in invertebrate populations and changes in benthic diversity (Hesthagen and Sandlund 2010). Many of the invertebrates consumed by the Eurasian minnow are also components of the diet of the brown trout, thus exacerbating competition between the introduced Eurasian minnow and brown trout (Hesthagen and Sandlund 2010). Additionally, Eurasian minnows have been shown to consume vendace (a salmonid) larvae (Huusko and Sutela 1997). If introduced, the Eurasian minnow's diet may include the larvae of U.S. native salmonids, including salmon and trout species (

Oncorhynchus

and

Salvelinus

spp.).

The Eurasian minnow serves as a host to parasites, such as

Gyrodactylus aphyae,

that it can transmit to other fish species, including salmon and trout (Zietara

et al.

2008). Once introduced, these parasites would likely spread to native salmon and trout species. Depending on pathogenicity, parasites of the

Gyrodactylus

species may cause high fish mortality (Bakke

et al.

1992).

Potential Impacts to Humans

We have no reports of the Eurasian minnow being harmful to humans.

Potential Impacts to Agriculture

The Eurasian minnow may impact agriculture by affecting aquaculture. This species harbors a parasite that may infect other fish species and can cause high fish mortality (Bakke

et al.

1992). Eurasian minnow populations can adversely impact both recruitment and growth of brown trout. Reduced recruitment and growth rates can reduce the economic value associated with brown trout aquaculture and recreational fishing.

Factors That Reduce or Remove Injuriousness for Eurasian Minnow

Control

Once introduced, it is difficult and costly to control a Eurasian minnow population (Sandlund 2008). Eradication may be possible from small waterbodies in cases where the population is likely to serve as a center for further spread, but no details are given on how to accomplish such eradication (Sandlund 2008). Control may also be possible using habitat modification or biocontrol (introduced predators); however, we know of no published accounts of long-term success by either method. Both control measures of habitat modification and biocontrol cause wildlife or habitat damages and are expensive mitigation strategies and, therefore, are not recommended or considered appropriate under the Injurious Wildlife Evaluation Criteria as a risk management plan for this species.

Potential Ecological Benefits for Introduction

There has been one incidence where the Eurasian minnow was introduced as a biocontrol for the Tune fly (Simuliidae) (Sandlund 2008). However, we do not have information on the success of this introduction. We are not aware of any other documented ecological benefits associated with the Eurasian minnow.

Factors That Contribute to Injuriousness for Prussian Carp

Current Nonnative Occurrences

This species is not found within the United States. However, it was recently reported to be established in waterways in southern Alberta, Canada, which is the first confirmed record in the wild in North America (Elgin

et al.

2014). The Prussian carp has been introduced to many countries of central and Western Europe. This species' current nonnative range includes the Asian countries of Armenia, Turkey, and Uzbekistan and the European countries of Belarus, Belgium, Czech Republic, Denmark, Estonia, France, Germany, Poland, and Switzerland (Britton 2011); it also includes the Iberian Peninsula (Ribeiro

et al.

2015).

Potential Introduction and Spread

Potential pathways of introduction include stocking for recreational fishing and aquaculture. Once introduced, the Prussian carp will naturally disperse to new waterbodies.

The Prussian carp prefers a temperate climate and resides in a variety of freshwater environments, including those with low dissolved oxygen concentrations and increased pollution (Britton 2011). The Prussian carp has an overall high climate match with a Climate 6 ratio of 0.414. This fish species has a high climate match to the Great Lakes region, northern Plains, some western mountain States, and parts of California. The Prussian carp has a medium climate match to much of the United States, including southern Alaska and regions of Hawaii. This species has a low climate match to the southeastern United States, especially Florida and along the Gulf Coast. This species is not found within the United States but has been recently discovered as established in Alberta, Canada (Elgin

et al.

2014); the climate match was run prior to this new information, so the results do not include any actual locations in North America.

If introduced, the Prussian carp is likely to spread and establish as a consequence of its tolerance to poor-quality environments, rapid growth rate, very rare ability to reproduce from unfertilized eggs (gynogenesis), and proven invasiveness outside of the native range.

Potential Impacts to Native Species (including Threatened and Endangered Species)

The Prussian carp is closely related and behaviorally similar to the crucian carp (Godard and Copp 2012). As with crucian carp, introduced Prussian carp may compete with native fish species, alter freshwater ecosystems, and serve as a vector for parasitic infections. Introduced Prussian carp have been responsible for the decreased biodiversity and overall populations of native fish (including native Cyprinidae), invertebrates, and plants (Anseeuw

et al.

2007, Lusk

et al.

2010). Thus, if introduced to the United States, the Prussian carp will likely affect numerous native Cyprinid species, including chub, dace, shiner, and minnow fish species (Froese and Pauly 2014c). Several of these native Cyprinids, such as the laurel dace (

Chrosomus saylori

) and humpback chub (

Gila cypha

), are listed as endangered or threatened under the Endangered Species Act.

Prussian carp can alter freshwater habitats. This was documented in Lake Mikri Prespa (Greece), where scientists correlated increased turbidity with increased numbers of Prussian carp (Crivelli 1995). This carp species increased turbidity levels by disturbing sediment during feeding. These carp also intensively fed on zooplankton, thus resulting in increased phytoplankton abundance and phytoplankton blooms (Crivelli 1995). Increased turbidity results in imbalances in nutrient cycling and ecosystem energetics. If introduced to the United States, Prussian carp could cause increased lake and pond turbidity, increased phytoplankton blooms, imbalances to ecosystem nutrient cycling, and altered freshwater ecosystems.

Several different types of parasitic infections, such as black spot disease (Posthodiplostomatosis) and from the parasite

Thelohanellus,

are associated with the Prussian carp (Ondračková

et al.

2002, Markovíc

et al.

2012). Black spot disease particularly affects young fish and can cause physical deformations, decreased growth, and decrease in body condition (Ondračková

et al.

2002). These parasites and the respective diseases may infect and decrease native fish stocks.

Prussian carp may compete with native fish species and may replace them in the trophic scheme. Large populations of Prussian carp can cause heavy predation on aquatic plants and invertebrates (Anseeuw

et al.

2007). Changes in ecosystem cycling and wildlife diversity may have negative effects on the aesthetic, recreational, and economic benefits of the environment.

Potential Impacts to Humans

We have no reports of the Prussian carp being harmful to humans.

Potential Impacts to Agriculture

The Prussian carp may impact agriculture by affecting aquaculture. As mentioned in the

Potential Impacts to Native Species

section, Prussian carp harbor several types of parasites that may cause physical deformations, decreased growth, and decrease in body condition (Ondračková

et al.

2002). Impaired fish physiology and health detract from the productivity and value of commercial aquaculture.

Factors That Reduce or Remove Injuriousness for Prussian Carp

Control

We are not aware of any documented control methods for the Prussian carp. The piscicide rotenone has been used to control the common carp and crucian carp population (Ling 2003) and may be effective against Prussian carp. However, rotenone is not target-specific (Wynne and Masser 2010). Depending on the applied concentration, rotenone kills other aquatic species in the water body. Some fish species are more susceptible than others, and, even if effective against Prussian carp, the use of this piscicide may kill native species (Allen

et al.

2006). Control measures that would harm other wildlife are not recommended as mitigation to reduce the injurious characteristics of this species and, therefore, do not meet control measures under the Injurious Wildlife Evaluation Criteria.

Potential Ecological Benefits for Introduction

We are not aware of any documented ecological benefits for the introduction of the Prussian carp.

Factors That Contribute to Injuriousness for Roach

Current Nonnative Occurrences

This species is not found in the United States. The roach has been introduced and become established in England, Ireland, Italy, Madagascar, Morocco, Cyprus, Portugal, the Azores, Spain, and Australia (Rocabayera and Veiga 2012).

Potential Introduction and Spread

Potential introduction pathways include stocking for recreational fishing and use as bait fish. Once introduced, released, or escaped, the roach naturally disperses to new waterways within the watershed.

This species prefers a temperate climate and can reside in a variety of freshwater habitats (Riehl and Baensch 1991). Hydrologic changes, such as weirs and dams that extend aquatic habitats that are otherwise scarce, enhance the potential spread of the roach (Rocabayera and Veiga 2012). The roach has an overall high climate match to the United States with a Climate 6 ratio of 0.387. Particularly high climate matches occurred in southern and central Alaska, the Great Lakes region, and the western mountain States. The Southeast and Southwest have low climate matches.

If introduced, the roach is likely to spread and establish due to its highly adaptive nature toward habitat and diet choice, high reproductive potential, ability to reproduce with other cyprinid species, long lifespan, and extraordinary mobility. This species has also proven invasive outside of its native range.

Potential Impacts to Native Species (including Endangered and Threatened Species)

Potential effects to native species from the introduction of the roach include competition over food and habitat resources, hybridization, altered ecosystem nutrient cycling, and parasite and pathogenic bacteria transmission. The roach is a highly adaptive species and will switch between habitats and food sources to best avoid predation and competition from other species (Winfield and Winfield 1994). The roach consumes an omnivorous generalist diet, including benthic invertebrates (especially mollusks), zooplankton, plants, and detritus (Rocabayera and Veiga 2012). With such a varied diet, the roach would be expected to compete with numerous native fish species from multiple trophic levels. The trophic level is the position an organism occupies in a food chain. Such species may include shiners, daces, chubs, and stonerollers, several of which are federally listed as endangered or threatened.

Likewise, introduction of the roach would be expected to detrimentally affect native mollusk species (including mussels and snails), some of which may be federally endangered or threatened. One potentially affected species is the endangered Higgins' eye pearly mussel (

Lampsilis higginsii

), which is native to the upper Mississippi River watershed, where there is high climate match for the roach species. Increased competition with and predation on native species may alter trophic cycling and diversity of native aquatic species.

The roach can hybridize with other fish species of its subfamily (Leuciscinae), including rudd and bream (Pitts

et al.

1997, Kottelat and Freyhof 2007). In Ireland, the roach has hybridized with the rudd (

Scardinius erythrophthalmus

) and the bream (

Abramis brama

); all three are in the subfamily Leuciscinae. Although the bream is not found in the United States, the rudd is already considered invasive in the Great Lakes (Fuller

et al.

1999, Kapuscinski

et al.

2012). Hybrids of roaches and rudds could exacerbate the potential adverse effects (competition) of each separate species (Rocabayera and Veiga 2012). Furthermore, the roach will likely be able to hybridize with some U.S. native species in the same subfamily, which includes minnows.

Large populations of the roach may alter nutrient cycling in lake ecosystems. Increased populations of roach may prey heavily on zooplankton, thus resulting in increased phytoplankton communities and algal blooms (Rocabayera and Veiga 2012). These changes alter nutrient cycling and can consequently affect native aquatic species that depend on certain nutrient balances.

Several parasitic infections, including worm cataracts, black spot disease, and tapeworms, have been associated with the roach (Rocabayera and Veiga 2012). The pathogenic bacterium

Aeromonas salmonicida

also infects the roach, causing furunculosis (Wiklund and Dalsgaard 1998). This disease causes skin ulcers and hemorrhaging. The disease can be spread through a fish's open sore. This disease affects both farmed and wild fish. The causative bacteria

A. salmonicida

has been isolated from fish in U.S. freshwaters (USFWS 2011). The roach may spread these parasites and bacteria to new environments and native fish species.

Potential Impacts to Humans

We have no reports of the roach being harmful to humans.

Potential Impacts to Agriculture

The roach may affect agriculture by decreasing aquaculture productivity if they are unintentionally introduced into aquaculture operations in the United States, such as when invaded watersheds flood aquaculture ponds or by accidentally being included in a shipment of fish, then outcompeting and preying on the aquacultured fish, spreading pathogens, or hybridizing with farmed fish. Hybridization can reduce the reproductive success and productivity of the commercial fisheries and aquaculture facilities.

Roaches harbor several parasitic infections (Rocabayera and Veiga 2012) that can impair fish physiology and health. The pathogenic bacterium

Aeromonas salmonicida

infects the roach, causing furunculosis (Wiklund and Dalsgaard 1998). The disease can be spread through a fish's open sore when the bacteria is shed from the ulcerated skin and survives in water to infect another fish. Introduction and spread of parasites and pathogenic bacterium to an aquaculture facility can result in increased incidence of fish disease and mortality and decreased productivity and value.

Factors That Reduce or Remove Injuriousness for Roach

Control

An introduced roach population would be difficult to control (Rocabayera and Veiga 2012). Application of the piscicide rotenone may be effective for limited populations of small fish. However, rotenone is not target-specific (Wynne and Masser 2010). Depending on the applied concentration, rotenone kills other aquatic species in the water body. Some fish species are more susceptible than others, and the use of this piscicide may kill native species. Control measures that would harm other wildlife are not recommended as mitigation to reduce the injurious characteristics of this species and, therefore, do not meet control measures under the Injurious Wildlife Evaluation Criteria.

Potential Ecological Benefits for Introduction

We are not aware of any documented ecological benefits for the introduction of the roach.

Factors That Contribute to Injuriousness for Stone Moroko

Current Nonnative Occurrences

This fish species is not found within the United States. The stone moroko has been introduced and become established throughout Europe and Asia. Within Asia, this fish species is invasive in Afghanistan, Armenia, Iran, Kazakhstan, Laos, Taiwan, Turkey, and Uzbekistan (Copp 2007). In Europe, this fish species' nonnative range includes Albania, Austria, Belgium, Bulgaria, Czech Republic, Denmark, France, Germany, Greece, Hungary, Italy, Lithuania, Moldova, Montenegro, the Netherlands, Poland, Romania, Russia, Serbia, Slovakia, Spain, Sweden, Switzerland, Ukraine, and the United Kingdom (Copp 2007). The stone moroko's nonnative range also includes Algeria and Fiji (Copp 2007).

Potential Introduction and Spread

The primary introduction pathways are as unintentional inclusion in the transport water of intentionally stocked fish shipments for both recreational fishing and aquaculture, released or escaped bait, and released or escaped ornamental fish. Once introduced, the stone moroko naturally disperses to new waterways within a watershed. Since the 1960s, this fish has invaded nearly every European country and many Asian countries (Copp

et al.

2005).

The stone moroko inhabits a temperate climate (Baensch and Riehl 1993) and a variety of freshwater habitats, including those with poor dissolved oxygen concentrations (Copp 2007). The stone moroko has an overall high climate match to the United States with a Climate 6 ratio of 0.557. This species has a high or medium climate match to most of the United States. The highest matches are in the Southeast, Great Lakes, central plains, and West Coast.

If introduced, the stone moroko is highly likely to establish and spread. This fish species is a habitat generalist and diet generalist and is quick growing, highly adaptable to new environments, and highly mobile. Additionally, the stone moroko has proven invasive outside of its native range (Copp 2007, Kottelat and Freyhof 2007, Witkowski 2011, Yalçın-Özdilek

et al.

2013).

Potential Impacts to Native Species (including Endangered and Threatened Species)

In much of the stone moroko's nonnative range, the introduction of this species has been linked to the decline of native freshwater fish species (Copp 2007). The stone moroko could potentially adversely affect native species through predation, competition, disease transmission, and altering freshwater ecosystems (Witkowski 2011).

Stone moroko introductions have mostly originated from unintentional inclusion in the transport water of intentionally stocked fish species. In many stocked ponds, the stone moroko actually outcompetes the farmed fish species for food resources, which results in decreased production of the farmed fish (Witkowski 2011). The stone moroko's omnivorous diet includes insects, fish, fish eggs, molluscs, planktonic crustaceans, algae (Froese and Pauly 2014g), and plants (Kottelat and Freyhof 2007). With this diet, the stone moroko would compete with many native U.S. freshwater fish, including minnow, dace, sunfish, and darter species.

In the United Kingdom, Italy, China, and Russia, the introduction of the stone moroko correlates with dramatic declines in native fish populations and species diversity (Copp 2007). The stone moroko first competes with native fish for food resources and then predates on the eggs, larvae, and juveniles of these same native fish species (Pinder 2005, Britton

et al.

2007). In England, where stone morokos were introduced, they dominated the fish community quickly, and the other fish species exhibited decreased growth rates and reproduction, as well as shifts in their trophic levels (Britton

et al.

2010b).

The stone moroko is a vector of the pathogenic, rosette-like agent

Sphaerothecum destruens

(Gozlan

et al.

2005, Pinder

et al.

2005), which is a documented pathogen of farmed and wild European fish. The stone moroko is a healthy host for this nonspecific pathogen that could threaten aquaculture trade, including that of salmonids (Gozlan

et al.

2009). This pathogen infects a fish's internal organs causing spawning failure, organ failure, and death (Gozlan

et al.

2005). This pathogen has been documented as infecting the sunbleak (

Leucaspius delineatus

), which are native to eastern Europe, and Chinook salmon (

Oncorhynchus tshawytscha

), Atlantic salmon, and the fathead minnow (

Pimephales promelas

), all three of which are native to the United States (Gozlan

et al.

2005).

The stone moroko consumes large quantities of zooplankton. The declines in zooplankton population results in increased phytoplankton populations, which in turn causes algal blooms and unnaturally high nutrient loads (eutrophication). These changes can cause imbalanced nutrient cycling, decrease dissolved oxygen concentrations, and adversely impact the health of native aquatic species.

Potential Impacts to Humans

We have no reports of the stone moroko being harmful to humans.

Potential Impacts to Agriculture

The stone moroko may affect agriculture by decreasing aquaculture productivity. This species often contaminates farmed fish stocks and competes with the farmed species for food resources, resulting in decreased aquaculture productivity (Witkowski 2011). The stone moroko is an unaffected carrier of the pathogenic, rosette-like agent

Sphaerothecum destruens

(Gozlan

et al.

2005, Pinder

et al.

2005). This pathogen is transmitted through water and causes reproductive failure, disease, and death to farmed fish. This pathogen is not species-specific and has been known to infect cyprinid and salmonid fish species.

Sphaerothecum destruens

is responsible for disease outbreaks in North American salmonids and causes mortality in both juvenile and adult fish (Gozlan

et al.

2009). If this pathogen was introduced to an aquaculture facility, it is likely to spread and infect numerous fish, resulting in high mortality. Further research is needed to ascertain this pathogen's prevalence in the wild environment (Gozlan

et al.

2009).

Factors That Reduce or Remove Injuriousness for Stone Moroko

Control

An established, invasive stone moroko population would be both difficult and costly to control (Copp 2007). Additionally, this fish species has a higher tolerance for the piscicide rotenone than most other fish belonging to the cyprinid group (Allen

et al.

2006). Application of rotenone for stone moroko control may kill native aquatic fish species. Control measures that would harm other wildlife are not recommended as mitigation to reduce the injurious characteristics of this species and, therefore, do not meet control measures under the Injurious Wildlife Evaluation Criteria.

Potential Ecological Benefits for Introduction

We are not aware of any documented ecological benefits for the introduction of the stone moroko.

Factors That Contribute to Injuriousness for Nile Perch

Current Nonnative Occurrences

This species is not currently found within the United States. The Nile perch is invasive in the Kenyan, Tanzanian, and Ugandan watersheds of Lake Victoria and Lake Kyoga (Africa). This species has also been introduced to Cuba (Welcomme 1988).

Potential Introduction and Spread

This species was stocked in Texas reservoirs, although this population failed to establish (Fuller

et al.

1999, Howells 2001). However, with continued release events, we anticipate that the Nile perch is likely to establish in parts of the United States, including the Southeast, Southwest, Hawaii, Puerto Rico, and U.S. Virgin Islands. Likely introduction pathways include use for aquaculture and recreational fishing. Over the past 60 years, the Nile perch has invaded, established, and become the dominant fish species within this species' nonnative African range (Witte 2013).

The Nile perch prefers a tropical climate and can inhabit a variety of freshwater and brackish habitats (Witte 2013). The Nile perch has an overall medium climate match to the United States with a Climate 6 ratio of 0.038. Of the 11 species in this rule, the Nile perch has the only overall medium climate match. However, this fish species has a high climate match to the Southeast (Florida and Gulf Coast), Southwest (California), Hawaii, Puerto Rico, and the U.S. Virgin Islands.

If introduced into the United States, the Nile perch is likely to establish and spread due to this species' nature as a habitat generalist and generalist predator, long lifespan, quick growth rate, high reproductive potential, extraordinary mobility, and proven invasiveness outside of the species' native range (Witte 2013, Asila and Ogari 1988, Ribbinick 1982).

Potential Impacts to Native Species (including Endangered and Threatened Species)

Potential impacts of introduction of the Nile perch include outcompeting and preying on native species, altering habitats and trophic systems, and disrupting ecosystem nutrient cycling. The Nile perch can produce up to 15 million eggs per breeding cycle (Asila and Ogari 1988), likely contributing to this species' efficiency and effectiveness in establishing an introduced population.

Historical evidence from the Lake Victoria (Africa) basin indicate that the Nile perch outcompeted and preyed on at least 200 endemic fish species, leading to their extinction (Kaufman 1992, Snoeks 2010, Witte 2013). Many of the affected species were haplochromine cichlid fish species, and the populations of native lung fish (

Protopterus aethiopicus

) and catfish species (

Bagrus docmak, Xenoclarias eupogon, Synodontis victoria

) also witnessed serious declines (Witte 2013). By the late 1980s, only three fish species, including the cyprinid

Rastrineobolas argentea

and the introduced Nile perch and Nile tilapia (

Oreochromis niloticus

), were common in Lake Victoria (Witte 2013).

The haplochromine cichlid species comprised 15 subtrophic groups with varied food (detritus, phytoplankton, algae, plants, mollusks, zooplankton, insects, prawns, crabs, fish, and parasites) and habitat preferences (Witte and Van Oijen 1990, Van Oijen 1996). The depletion of so many fish species has drastically altered the Lake Victoria ecosystem's trophic-level structure and biodiversity. These changes resulted in abnormally high lake eutrophication and frequency of algal blooms (Witte 2013).

The depletion of the native fish species in Lake Victoria by Nile perch led to the loss of income and food for local villagers. Nile perch was not a suitable replacement for traditional fishing. Fishing for this larger species required equipment that was prohibitively more expensive, required processing that could not be done by the wife and children, required the men to be away for extended periods, and decreased the availability of fish for household consumption (Witte 2013).

If introduced to the United States, Nile perch are expected to prey on small native fish species, such as mudminnows, cyprinids, sunfishes, and darters. Nile perch would likely prey on, compete with, and decrease the species diversity of native cyprinid fish. Nile perch are expected to compete with larger native fish species, including largemouth bass (

Micropterus salmoides)

and smallmouth bass (

Micropterus dolomieu

), blue catfish (

Ictalurus furcatus

), channel catfish (

Ictalurus punctatus

), and flathead catfish (

Pyodictis olivaris

). These native fish species are not only economically important to both commercial and recreational fishing, but are integral components of freshwater ecosystems.

Potential Impacts to Humans

We have no reports of the Nile perch being harmful to humans.

Potential Impacts to Agriculture

We are not aware of any reported effects to agriculture. However, Nile perch may affect aquaculture if they are unintentionally introduced into aquaculture operations in the United States, such as when invaded watersheds flood aquaculture ponds or by accidentally being included in a shipment of fish, by outcompeting and preying on the aquacultured fish.

Factors That Reduce or Remove Injuriousness for Nile Perch

Control

Nile perch grow to be large fish with a body length of 2 m (6 ft) and maximum weight of 200 kg (440 lb) (Ribbinick 1987). Witte (2013) notes that this species would be difficult and costly to control. We are not aware of any documented reports of successfully controlling or eradicating an established Nile perch population.

Potential Ecological Benefits for Introduction

We are not aware of any documented ecological benefits for the introduction of the Nile perch.

Factors That Contribute to Injuriousness for the Amur Sleeper

Current Nonnative Occurrences

This species has not been reported within the United States. The Amur sleeper is invasive in Europe and Asia in the countries of Belarus, Bulgaria, Croatia, Estonia, Hungary, Latvia, Lithuania, Moldova, Poland, Romania, Serbia, Slovakia, Ukraine, Russia, and

Mongolia (Froese and Pauly 2014j, Grabowska 2011).

Potential Introduction and Spread

Although the Amur sleeper has not yet been introduced to the United States, the likelihood of introduction, release, or escape is high as evidenced by the history of introduction over a broad geographic region of Eurasia. Since its first introduction outside of its native range in 1916, the Amur sleeper has invaded 15 Eurasian countries and become a widespread, invasive fish throughout European freshwater ecosystems (Copp

et al.

2005, Grabowska 2011). The introduction of the Amur sleeper has been attributed to release and escape of aquarium and ornamental fish, unintentional and intentional release of Amur sleepers used for bait, and the unintentional inclusion in the transport water of intentionally stocked fish (Reshetnikov 2004, Grabowska 2011, Reshetnikov and Ficetola 2011).

Once this species has been introduced, it has proven to be capable of establishing (Reshetnikov 2004). The established populations can have rapid rates of expansion. Upon introduction into the Vistula River in Poland, the Amur sleeper expanded its range by 44 km (27 mi) the first year and up to 197 km (122 mi) per year thereafter (Grabowska 2011).

Most aquatic species are constrained in distribution by temperature, dissolved oxygen levels, and lack of flowing water. However, the Amur sleeper has a wide water temperature preference (Baensch and Riehl 2004), can live in poorly oxygenated waters, and may survive in dried-out or frozen water bodies by burrowing into and hibernating in the mud (Grabowska 2011). The Amur sleeper has an overall high climate match to the United States with a Climate 6 ratio of 0.376. The climate match is highest in the Great Lakes region (Ohio, Indiana, Illinois, Michigan, Wisconsin, and Minnesota), central and high Plains (Iowa, Nebraska, and Missouri), western mountain States (South Dakota, North Dakota, Montana, Wyoming, and Colorado), and central to eastern Alaska.

If introduced, the Amur sleeper would be expected to establish and spread in the wild due to this species' ability as a habitat generalist, generalist predator, rapid growth, high reproductive potential, adaptability to new environments, extraordinary mobility, and a history of invasiveness outside of the native range.

Potential Impacts to Native Species (including Endangered and Threatened Species)

The Amur sleeper is a voracious generalist predator whose diet includes crustaceans, insects, and larvae of mollusks, fish, and amphibian tadpoles (Bogutskaya and Naseka 2002, Reshetnikov 2008). Increased predation with the introduction of the Amur sleeper has resulted in decreased species richness and decreased population of native fish (Grabowska 2011). In some areas, the Amur sleeper's eating habits have been responsible for the dramatic decline in juvenile fish and amphibian species (Reshetnikov 2003). Amur sleepers prey on juvenile stages and can cause decreased reproductive success and reduced populations of the native fish and amphibians (Mills

et al.

2004). Declines in lower trophic-level populations (invertebrates) also result in increased competition among native predatory fish, including the European mudminnow (

Umbra krameri

) (Grabowska 2011).

Two species similar to the European mudminnow, the eastern mudminnow (

Umbra pygmaea

) and the central mudminnow (

Umbra limi

), are native to the eastern United States. Both of these species are integral members of freshwater ecosystems, with the eastern mudminnow ranging from New York to Florida (Froese and Pauly 2014n), and the central mudminnow residing in the freshwater of the Great Lakes, Hudson Bay, and Mississippi River basins (Froese and Pauly 2014o). Introduced Amur sleepers could prey on and reduce the population of native U.S. mudminnow species.

The introduction or establishment of the Amur sleeper is also expected to reduce native wildlife biodiversity. In the Selenga River (Russia), the Amur sleeper competes with the native Siberian roach (

Rutilus rutilus lacustris

) and Siberian dace (

Leuciscus leuciscus baicalensis

) for food resources. This competition results in decreased populations of native fish species, which may result in economic losses and negative effects on commercial fisheries (Litvinov and O'Gorman 1996, Grabowska 2011).

Species similar to Siberian roach and Siberian dace that are native to the United States include those of the genus

Chrosomus,

such as the blackside dace (

Chrosomus cumberlandensis

), northern redbelly dace (

C. eos

), southern redbelly dace (

C. erythrogaster

), and Tennessee dace (

C. tennesseensis

). Like with the Siberian roach and the Siberian dace, introduced populations of the Amur sleeper may compete with native dace fish species, resulting in population declines of these native species.

Additionally, the Amur sleeper harbors parasites, including

Nippotaenia mogurndae

and

Gyrodactylus perccotti.

The introduction of the Amur sleeper has resulted in the simultaneous introduction of both parasites to the Amur sleeper's nonnative range. These parasites have expanded their own nonnative range and successfully infected new hosts of native fish species (Košuthová

et al.

2008).

Potential Impacts to Humans

We have no reports of Amur sleeper being harmful to humans.

Potential Impacts to Agriculture

The Amur sleeper may affect agriculture by decreasing aquaculture productivity. This fish species hosts parasites, including

Nippotaenia mogurndae

and

Gyrodactylus perccotti.

These parasites may switch hosts (Košuthová

et al.

2008) and infect farmed species involved in aquaculture. Increased parasite load impairs a fish's physiology and general health, and consequently may decrease aquaculture productivity.

Factors That Reduce or Remove Injuriousness for Amur Sleeper

Control

Once introduced and established, it would be difficult, if not impossible, to control or eradicate the Amur sleeper. All attempts to eradicate the Amur sleeper once it had established a reproducing population have been unsuccessful (Litvinov and O'Gorman 1996). Natural predators include pike, snakeheads, and perch (Bogutskaya and Naseka 2002). Not all freshwater systems have these or similar predatory species, and thus would allow the Amur sleeper population to be uncontrolled.

Some studies have indicated that the Amur sleeper may be eradicated by adding calcium chloride (CaCl

2

) or ammonium hydroxide (NH

4

OH) to the water body (Grabowska 2011). However, this same study found that the Amur sleeper was one of the most resistant fish species to either treatment. Thus, the use of either treatment would likely negatively affect many other native organisms and is not considered a viable option. Control measures that would harm other wildlife are not recommended as mitigation to reduce the injurious characteristics of this species and, therefore, do not meet control measures under the Injurious Wildlife Evaluation Criteria.

Potential Ecological Benefits for Introduction

We are not aware of any documented ecological benefits for the introduction of the Amur sleeper.

Factors That Contribute to Injuriousness for European Perch

Current Nonnative Occurrences

This fish species is not found within the United States. The European perch has been introduced and become established in several countries, including Ireland, Italy, Spain, Australia, New Zealand, China, Turkey, Cyprus, Morocco, Algeria, and South Africa.

Potential Introduction and Spread

The main pathway of introduction is through stocking for recreational fishing. Once stocked, this fish species has expanded its nonnative range by swimming through connecting waterbodies to new areas within the same watershed.

The European perch prefers a temperate climate (Riehl and Baensch 1991, Froese and Pauly 2014k). This species can reside in a wide variety of aquatic habitats ranging from freshwater to brackish water (Froese and Pauly 2014k). The European perch has an overall high climate match to the United States, with a Climate 6 ratio of 0.438, with locally high matches to the Great Lakes region, central Texas, western mountain States, and southern and central Alaska. Hawaii ranges from low to high matches. Much of the rest of the country has a medium climate match.

If introduced to the United States, the European perch is likely to spread and establish in the wild as a generalist predator that is able to adapt to new environments and outcompete native fish species. Additionally, this species has proven to be invasive outside of its native range.

Potential Impacts to Native Species (including Threatened and Endangered Species)

The European perch can impact native species through outcompeting and preying on them and by transmitting disease. This introduced fish species competes with other European native species for both food and habitat resources (Closs

et al.

2003) and has been implicated in the local extirpation (in Western Australia) of the mudminnow (

Galaxiella munda

) (Moore 2008, ISSG 2010).

In addition to potentially competing with the native yellow perch (

Perca flavescens

), the European perch may also hybridize with this native species, resulting in irreversible changes to the genetic structure of this important native species (Schwenk

et al.

2008). Hybridization can reduce the fitness of the native species and, in some cases, has resulted in drastic population declines causing endangered classification and even extinction (Mooney and Cleland 2001). Furthermore, the yellow perch has value for both commercial and recreational fishing and is also an important forage fish in many freshwater ecosystems (Froese and Pauly 2014p). Thus, declines in yellow perch populations can result in serious consequences for upper trophic-level piscivorous fish. Additionally, European perch can form dense populations competing with each other to the extent that they stunt their own growth (NSW DPI 2013).

European perch prey on zooplankton, macroinvertebrates, and fish; thus, the introduction of this species can significantly alter trophic-level cycling and affect native freshwater communities (Closs

et al.

2003). European perch are reportedly voracious predators that consume small Australian fish (pygmy perch

Nannoperca spp.,

rainbowfish (various species), and carp gudgeons

Hypseleotris spp.

); and the eggs and fry of silver perch (

Bidyanus bidyanus

), golden perch (

Macquaria ambigua

), Murray cod (

Maccullochella peelii

), and introduced trout species (rainbow, brook (

Salvelinus fontinalis

), and brown trout (NSW DPI 2013)). In one instance, European perch consumed 20,000 newly released nonnative rainbow trout fry from a reservoir in southwestern Australia in less than 72 hours (NSW DPI 2013). Rainbow trout are native to the western United States. If introduced into U.S. freshwaters, European perch would be expected to prey on rainbow trout and other native fish.

The European perch can also harbor and spread the viral disease Epizootic Haematopoietic Necrosis (EHN) (NSW DPI 2013). This virus can cause mass fish mortalities and affects silver perch, Murray cod,

Galaxias

fish, and Macquarie perch (

Macquaria australasica

) in their native habitats. The continued spread of this virus (with the introduction of the European perch) has been partly responsible for declining populations of native Australian fish species (NSW DPI 2013). This virus is currently restricted to Australia but could expand its international range with the introduction of European perch to new waterways where native species would have no natural resistance.

Potential Impacts to Humans

We have no reports of the European perch being harmful to humans.

Potential Impacts to Agriculture

The European perch may affect agriculture by decreasing aquaculture productivity. The European perch may potentially spread the viral disease EHN (NSW DPI 2013) to farmed fish in aquaculture facilities. Although this virus is currently restricted to Australia, this disease can cause mass fish mortalities and is known to affect other fish species (NSW DPI 2013).

Factors That Reduce or Remove Injuriousness for European Perch

Control

It would be extremely difficult to control or eradicate a population of European perch. However, Closs

et al.

(2003) examined the feasibility of physically removing (by netting and trapping) European perch from small freshwater environments. Although these researchers were able to reduce population numbers through repeated removal efforts, European perch were not completely eradicated from any of the freshwater lakes. Biological controls or chemicals might be effective; however, they would also have lethal effects on native aquatic species. Control measures that would harm other wildlife are not recommended as mitigation to reduce the injurious characteristics of this species and, therefore, do not meet control measures under the Injurious Wildlife Evaluation Criteria.

Potential Ecological Benefits for Introduction

We are not aware of any documented ecological benefits for the introduction of the European perch.

Factors That Contribute to Injuriousness for Zander

Current Nonnative Occurrences

The zander was intentionally introduced into Spiritwood Lake (North Dakota) in 1989 for recreational fishing. The North Dakota Game and Fish Department reports that a small, established population occurs in this lake (Fuller 2009) and that a 32-in (81.3-cm) zander was caught by an angler in 2013 (North Dakota Game and Fish 2013). This was the largest zander in the lake reported to date, which could indicate that the species is finding suitable living conditions. We are not aware of any other occurrences of zanders within the United States. This fish species has been introduced and become established through much of

Europe, regions of Asia (China, Kyrgyzstan, and Turkey), and Africa (Algeria, Morocco, and Tunisia). Within Europe, zanders have established populations in Belgium, Bulgaria, Croatia, Cyprus, Denmark, France, Italy, the Netherlands, Portugal, the Azores, Slovenia, Spain, Switzerland, and the United Kingdom.

Potential Introduction and Spread

The zander has been introduced to the United States, and a small population exists in Spiritwood Lake, North Dakota. Primary pathways of introduction have originated with recreational fishing and aquaculture stocking. The zander has also been introduced to control unwanted cyprinids (Godard and Copp 2011). Additionally, the zander disperse unaided into new waterways.

The zander prefers a temperate climate (Froese and Pauly 2014l). This species resides in a variety of freshwater and brackish environments, including turbid waters with increased nutrient concentrations (Godard and Copp 2011). The overall climate match to the United States is high with a Climate 6 ratio of 0.374. The zander has high climate matches in the Great Lakes region, northern Plains, western mountain States, and Pacific Northwest. Medium climate matches include southern Alaska, western mountain States, central Plains, and mid-Atlantic and New England regions. Low climate matches occur in Florida, along the Gulf Coast, and desert Southwest regions.

If introduced, the zander would likely establish and spread as a consequence of its nature as a generalist predator, ability to hybridize with multiple fish species, extraordinary mobility, long lifespan (maximum 24 years) (Godard and Copp 2011), and proven invasiveness outside of the native range.

Potential Impacts to Native Species (including Endangered and Threatened Species)

The zander may affect native fish species by outcompeting and preying on them, transferring pathogens to them, and hybridizing with them. The zander is a top-level predator and competes with other native piscivorous fish species. In Western Europe, increased competition from introduced zanders resulted in population declines of native northern pike and European perch (Linfield and Rickards 1979). If introduced to the United States, the zander is projected to compete with native top-level predators such as the closely related walleye (

Sander vitreus

), sauger (

Sander canadensis

), and northern pike.

The zander's diet includes juvenile smelt, ruffe, European perch, vendace, roach, and

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