# Endangered and Threatened Species; Designation of Critical Habitat for the Endangered New York Bight, Chesapeake Bay, Carolina and South Atlantic Distinct Population Segments of Atlantic Sturgeon and the Threatened Gulf of Maine Distinct Population Segment of Atlantic Sturgeon

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URL: https://www.frixlaw.com/law-library/documents/fr%3A2017-17207

## Record

- **Collection:** Federal Register
- **Document type:** Rule
- **Published:** August 17, 2017
- **Citation:** 82 FR 39160

## Text

DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Part 226
[Docket No. 150818735-7452-02]
RIN 0648-BF28
Endangered and Threatened Species; Designation of Critical Habitat for the Endangered New York Bight, Chesapeake Bay, Carolina and South Atlantic Distinct Population Segments of Atlantic Sturgeon and the Threatened Gulf of Maine Distinct Population Segment of Atlantic Sturgeon

AGENCY:

National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.

ACTION:

Final rule.

SUMMARY:

We (NMFS) are issuing this final rule to designate critical habitat for the threatened Gulf of Maine distinct population segment (DPS) of Atlantic sturgeon, the endangered New York Bight DPS of Atlantic sturgeon, the endangered Chesapeake Bay DPS of Atlantic sturgeon, the endangered Carolina DPS of Atlantic sturgeon and the endangered South Atlantic DPS of Atlantic sturgeon pursuant to the Endangered Species Act (ESA). Specific occupied areas designated as critical habitat for the Gulf of Maine DPS of Atlantic sturgeon contain approximately 244 kilometers (km; 152 miles) of aquatic habitat in the following rivers of Maine, New Hampshire, and Massachusetts: Penobscot, Kennebec, Androscoggin, Piscataqua, Cocheco, Salmon Falls, and Merrimack. Specific occupied areas designated as critical habitat for the New York Bight DPS of Atlantic sturgeon contain approximately 547 km (340 miles) of aquatic habitat in the following rivers of Connecticut, Massachusetts, New York, New Jersey, Pennsylvania, and Delaware: Connecticut, Housatonic, Hudson, and Delaware. Specific occupied areas designated as critical habitat for the Chesapeake Bay DPS of Atlantic sturgeon contain approximately 773 km (480 miles) of aquatic habitat in the following rivers of Maryland, Virginia, and the District of Columbia: Potomac, Rappahannock, York, Pamunkey, Mattaponi, James, Nanticoke, and the following other water body: Marshyhope Creek. Specific occupied areas designated as critical habitat for the Carolina DPS of Atlantic sturgeon contain approximately 1,939 km (1,205 miles) of aquatic habitat in the following rivers of North Carolina and South Carolina: Roanoke, Tar-Pamlico, Neuse, Cape Fear, Northeast Cape Fear, Waccamaw, Pee Dee, Black, Santee, North Santee, South Santee, and Cooper, and the following other water body: Bull Creek. Specific occupied areas designated as critical habitat for the South Atlantic DPS of Atlantic sturgeon contain approximately 2,883 km (1,791 miles) of aquatic habitat in the following rivers of South Carolina, Georgia, and Florida: Edisto, Combahee-Salkehatchie, Savannah, Ogeechee, Altamaha, Ocmulgee, Oconee, Satilla, and St. Marys Rivers.

DATES:

This rule becomes effective September 18, 2017.

ADDRESSES:

The final rule, maps, Final Impacts Analysis Reports and Final Regulatory Flexibility Analyses used in preparation of this final rule are available on the NMFS Greater Atlantic Regional Fisheries Office (GARFO) Web site at
http://www.greateratlantic.fisheries.noaa.gov/,
and NMFS Southeast Regional Fisheries Office (SERO) Web site at
http://sero.nmfs.noaa.gov/,
or by contacting Lynn Lankshear, NMFS, GARFO, 55 Great Republic Drive, Gloucester, MA 01930 or Andrew Herndon, NMFS, SERO, 263 13th Avenue South, Saint Petersburg, FL 33701.

FOR FURTHER INFORMATION CONTACT:

Lynn Lankshear, NMFS, GARFO at the address above or at 978-282-8473; Andrew Herndon, NMFS, SERO at the address above or at 727-824-5312; or Marta Nammack, NMFS, Office of Protected Resources at 301-427-8469.

SUPPLEMENTARY INFORMATION:

Background

In 2012, we listed five DPSs of Atlantic sturgeon under the ESA: Four were listed as endangered (New York Bight DPS and Chesapeake Bay DPS; 77 FR 5880; February 6, 2012; Carolina DPS and South Atlantic DPS; 77 FR 5914; February 6, 2012) and one as threatened (Gulf of Maine DPS; 77 FR 5880; February 6, 2012). On March 18, 2014, two non-governmental organizations filed a lawsuit alleging we had violated the ESA by failing to issue proposed and final rules designating critical habitat for the Atlantic sturgeon DPSs. Pursuant to a court-ordered settlement agreement, as modified, we agreed to submit proposed rules designating critical habitat for all DPSs of Atlantic sturgeon to the Office of the Federal Register by May 30, 2016. NMFS met that deadline and the two proposed critical habitat rules for the five Atlantic sturgeon DPSs were published on June 3, 2016. The proposed designations can be found at 81 FR 35701 for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs of Atlantic sturgeon and at 81 FR 36077 for the Carolina and South Atlantic DPSs of Atlantic sturgeon. A subsequent correction notice clarifying the types of manmade structures not included in the proposed designation for the Carolina and South Atlantic DPSs was published on June 28, 2016 (81 FR 41926). On February 11, 2016, NMFS and the USFWS published a final rule, Implementing Changes to the Regulations for Designating Critical Habitat (81 FR 7414) (the Implementation rule). As the Implementation rule discussed, the changes to these regulations were meant to more clearly describe the Services' past and ongoing practices for designating critical habitat. The proposed rules designating critical habitat for Atlantic sturgeon were largely drafted at the time the final Implementation rule was published, and were based on past practices incorporated into that rule. Thus, no substantive changes were made to the Atlantic sturgeon proposed rules as a result of finalizing the Implementation rule.

We solicited comments from the public on all aspects of the proposed rules and held public hearings in Gloucester, Massachusetts; Brunswick, Georgia; Charleston, South Carolina; and Morehead City, North Carolina. The initial regulatory flexibility analysis (IRFA) and the draft Impacts Analysis (DIA) prepared for each proposed rule pursuant to section 4(b)(2) of the ESA were made available for public review and comment along with the proposed rules. Upon request, we re-opened the public comment period of both proposed rules for an additional 15 days, from September 29, 2016, to October 14, 2016 (81 FR 66911; Sept. 29, 2016); the entire public comment period totaled 105 days. After receiving public comment, we decided to complete the critical habitat designations with one final rule. Combining the designations into a single final rule will provide greater clarity to the public about the total extent of the Atlantic sturgeon critical habitat designations, reduce redundancy, and enable the public to better understand the need to designate the affected areas.

Final regulatory flexibility analyses (FRFAs) and final Impacts Analysis reports (IAs) updating the initial analyses and reports, that were published with the proposed rules, have been prepared to accompany this final rule. Combining the regional FRFAs and

IAs into single documents would make it difficult for the public to keep track of which parts of the single documents built upon the underlying data from the individual analyses published with the proposed rules. In addition, at the proposed rule stage, our two NMFS regions used different methodologies to evaluate impacts, relying on consultation databases that are region specific to address the different circumstances applicable to a specific region. Courts have noted the ESA provides the USFWS and NMFS (the Services) with broad discretion and flexibility in determining which particular methodologies or approaches are best for each specific set of circumstances (
See, e.g., Bldg. Indus. Ass'n of the Bay Area et al.
v.
U.S. Dep't. of Commerce et al.,
No. 13-15132, 9th Cir., July 7, 2015 (upholding district court's ruling that the ESA does not require the agency to follow a specific methodology when designating critical habitat under section 4(b)(2)). Accordingly, we maintained the separate sets because combining the two distinct sets of regional analyses would not have gained any efficiencies and would have created overly complicated reports that would be difficult for the public to follow. The final analyses are publicly available (see
ADDRESSES
).

We determined that a key conservation objective for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs is to increase the abundance of each DPS by facilitating increased successful reproduction and recruitment to the marine environment. We know that each of these DPSs is at a low level of abundance and that successful reproduction and recruitment, which are essential to the conservation of the species, occur in a limited number of rivers for each DPS. Based on the best scientific information available for the life history needs of the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs, the physical features essential to the conservation of the species and that may require special management considerations or protection are:

(1) Hard bottom substrate (
e.g.,
rock, cobble, gravel, limestone, boulder, etc.) in low salinity waters (
i.e.,
0.0 to 0.5 parts per thousand (ppt) range) for settlement of fertilized eggs, refuge, growth, and development of early life stages;

(2) Aquatic habitat with a gradual downstream salinity gradient of 0.5 up to as high as 30 ppt and soft substrate (
e.g.,
sand, mud) between the river mouth and spawning sites for juvenile foraging and physiological development;

(3) Water of appropriate depth and absent physical barriers to passage (
e.g.,
locks, dams, thermal plumes, turbidity, sound, reservoirs, gear, etc.) between the river mouth and spawning sites necessary to support:

(i) Unimpeded movement of adults to and from spawning sites;

(ii) Seasonal and physiologically dependent movement of juvenile Atlantic sturgeon to appropriate salinity zones within the river estuary; and

(iii) Staging, resting, or holding of subadults or spawning condition adults.

Water depths in main river channels must also be deep enough (
e.g.,
at least 1.2 m) to ensure continuous flow in the main channel at all times when any sturgeon life stage would be in the river.

(4) Water, between the river mouth and spawning sites, especially in the bottom meter of the water column, with the temperature, salinity, and oxygen values that, combined, support:

(i) Spawning;

(ii) Annual and interannual adult, subadult, larval, and juvenile survival; and

(iii) Larval, juvenile, and subadult growth, development, and recruitment (
e.g.,
13 °C to 26 °C for spawning habitat and no more than 30 °C for juvenile rearing habitat, and 6 milligrams per liter (mg/L) dissolved oxygen (DO) or greater for juvenile rearing habitat).

We determined that the key conservation objectives for the Carolina and South Atlantic DPSs of Atlantic sturgeon are to increase the abundance of each DPS by facilitating increased survival of all life stages and facilitating adult reproduction and juvenile and subadult recruitment into the adult population. We determined the physical features essential to the conservation of the species and that may require special management considerations or protection, which support the identified conservation objectives, are:

(1) Hard bottom substrate (
e.g.,
rock, cobble, gravel, limestone, boulder, etc.) in low salinity waters (
i.e.,
0.0-0.5 ppt range) for settlement of fertilized eggs and refuge, growth, and development of early life stages;

(2) Transitional salinity zones inclusive of waters with a gradual downstream gradient of 0.5- up to 30 ppt and soft substrate (
e.g.,
sand, mud) between the river mouths and spawning sites for juvenile foraging and physiological development;

(3) Water of appropriate depth and absent physical barriers to passage (
e.g.,
locks, dams, thermal plumes, turbidity, sound, reservoirs, gear, etc.) between the river mouths and spawning sites necessary to support:

(i) Unimpeded movement of adults to and from spawning sites;

(ii) Seasonal and physiologically-dependent movement of juvenile Atlantic sturgeon to appropriate salinity zones within the river estuary; and

(iii) Staging, resting, or holding of subadults or spawning condition adults.

Water depths in main river channels must also be deep enough (at least 1.2 m) to ensure continuous flow in the main channel at all times when any sturgeon life stage would be in the river.

(4) Water quality conditions, especially in the bottom meter of the water column, between the river mouths and spawning sites with temperature and oxygen values that support:

(i) Spawning;

(ii) Annual and inter-annual adult, subadult, larval, and juvenile survival; and

(iii) Larval, juvenile, and subadult growth, development, and recruitment. Appropriate temperature and oxygen values will vary interdependently, and depending on salinity in a particular habitat. For example, 6.0 mg/L DO or greater likely supports juvenile rearing habitat, whereas DO less than 5.0 mg/L for longer than 30 days is less likely to support rearing when water temperature is greater than 25 °C. In temperatures greater than 26 °C, DO greater than 4.3 mg/L is needed to protect survival and growth. Temperatures of 13 to 26 °C likely to support spawning habitat.

Atlantic Sturgeon Natural History and Status

There are two subspecies of Atlantic sturgeon—the Gulf sturgeon (
Acipenser oxyrinchus desotoi
) and the Atlantic sturgeon (
Acipenser oxyrinchus oxyrinchus
). Historically, the Gulf sturgeon occurred from the Mississippi River east to Tampa Bay in Florida. Its present range extends from Lake Pontchartrain and the Pearl River system in Louisiana and Mississippi east to the Suwannee River in Florida. The Gulf sturgeon was listed as threatened under the ESA in 1991. This rule addresses the Atlantic sturgeon (
Acipenser oxyrinchus oxyrinchus
), which is distributed along the eastern coast of North America. Historically, sightings of Atlantic sturgeon have been reported from Hamilton Inlet, Labrador, Canada, south to the St. Johns River, Florida, United States. Reported occurrences south of the St. Johns River, Florida, have been rare but have increased recently with the evolution of acoustic telemetry coupled with increased receiver arrays.

Although there is considerable variability among species, all sturgeon species (Order
Acipenseriformes
) have

some common life history traits. They all: (1) Occur within the Northern Hemisphere; (2) spawn in freshwater over hard bottom substrates; (3) generally do not spawn annually; (4) are benthic foragers; (5) mature relatively late and are relatively long lived; and (6) are relatively sensitive to low DO levels (Dees, 1961; Sulak and Clugston, 1999; Billard and Lecointre, 2001; Secor and Niklitschek, 2002; Pikitch
et al.,
2005).

Atlantic sturgeon have all of the above traits. They occur along the eastern coast of North America from Hamilton Inlet, Labrador, Canada to Cape Canaveral, Florida, United States (Bigelow and Welsh, 1925; Dees, 1961; Vladykov and Greeley, 1963; NMFS and U.S. Fish and Wildlife Service (USFWS), 2007; T. Savoy, CT DEEP, pers. comm.). Atlantic sturgeon are a long-lived, late-maturing, estuarine-dependent, anadromous species with a maximum lifespan of up to 60 years, although the typical lifespan is probably much shorter (Sulak and Randall, 2002; Balazik
et al.,
2010). Atlantic sturgeon reach lengths up to 14 ft (4.27 m), and weigh over 800 pounds (363 kilograms (kg)). Many datasets demonstrate clinal variation in vital parameters of Atlantic sturgeon populations, with faster growth and earlier age at maturation in more southern systems. Atlantic sturgeon mature between the ages of 5 and 19 years in South Carolina (Smith
et al.,
1982), between 11 and 21 years in the Hudson River (Young
et al.,
1988), and between 22 and 34 years in the St. Lawrence River (Scott and Crossman, 1973). Atlantic sturgeon generally do not spawn every year. Multiple studies have shown that spawning intervals range from 1 to 5 years for males (Smith, 1985; Collins
et al.,
2000; Caron
et al.,
2002) and 2 to 5 years for females (Vladykov and Greeley, 1963; Van Eenennaam
et al.,
1996; Stevenson and Secor, 1999). Fecundity of Atlantic sturgeon has been correlated with age and body size, with egg production ranging from 400,000 to 8 million eggs per year (Smith
et al.,
1982; Van Eenennaam and Doroshov, 1998; Dadswell, 2006). The average age at which 50 percent of maximum lifetime egg production is achieved is estimated to be 29 years, approximately 3 to 10 times longer than for other bony fish species examined (Boreman, 1997).

Analysis of stomach contents for adults, subadults (
i.e.,
sexually immature Atlantic sturgeon that have emigrated from the natal estuary to the marine environment), and juveniles (
i.e.,
sexually immature Atlantic sturgeon that have not yet emigrated from the natal estuary) confirms that Atlantic sturgeon are benthic foragers (Ryder, 1888; Bigelow and Schroeder, 1953; Johnson
et al.,
1997; Secor
et al.,
2000; ASSRT, 2007; Guilbard
et al.,
2007; Hatin
et al.,
2007; Savoy, 2007; Dzaugis, 2013; McLean
et al.,
2013).

An anadromous species, Atlantic sturgeon spawns in freshwater of rivers that flow into a coastal estuary. Spawning adults migrate upriver in the spring, typically during February and March in southern systems, April and May in mid-Atlantic systems, and May and July in Canadian systems (Murawski and Pacheco, 1977; Smith, 1985; Bain, 1997; Smith and Clugston, 1997; Caron
et al.,
2002). A fall spawning migration has been hypothesized for many years (Rogers and Weber, 1995; Weber and Jennings, 1996; Moser
et al.,
1998) and was recently verified in the Roanoke River, North Carolina, and the Altamaha River, Georgia (Smith et. al., 2015; Ingram and Peterson 2016). There is also a growing body of evidence that some Atlantic sturgeon river populations have two spawning seasons comprised of different spawning adults (Balazik and Musick, 2015; Farrae
et al.,
2017). Since the listings, additional evidence of fall as well as spring spawning has been obtained for the Chesapeake Bay DPS of Atlantic sturgeon (Balazik
et al.,
2012; Hager
et al.,
2014; Kahn
et al.,
2014).

Spawning typically occurs in flowing water upriver of the salt front of estuaries and below the fall line of large rivers (Borodin, 1925; Leland, 1968; Scott and Crossman, 1973; Crance, 1987; Bain
et al.,
2000). The fall line is the boundary between an upland region of continental bedrock and an alluvial coastal plain, sometimes characterized by waterfalls or rapids. Spawning sites are well-oxygenated areas with flowing water ranging in temperature from 13 °C (55 °F) to 26 °C (79 °F), and hard bottom substrate such as cobble, hard clay, and bedrock (Ryder, 1888; Dees, 1961; Vladykov and Greeley, 1963; Scott and Crossman, 1973; Gilbert, 1989; Smith and Clugston, 1997; Bain
et al.,
2000; Collins
et al.,
2000; Balazik
et al.,
2012; Hager
et al.,
2014). Depth at which fish spawn and water depth leading to spawning sites may be highly variable. Atlantic sturgeon in spawning condition have been tracked and captured at depths up to 27 m (Borodin 1925; Dees 1961; Hatin
et al.,
2002; Balazik
et al.,
2012; Hager
et al.,
2014).

Within minutes of being fertilized, the eggs become sticky and adhere to the substrate for the relatively short and temperature-dependent period of larval development (Ryder, 1888; Vladykov and Greeley, 1963; Murawski and Pacheco, 1977; Smith
et al.,
1980; Van den Avyle, 1984; Mohler, 2003). Hatching occurs approximately 94 to 140 hours after egg deposition at temperatures of 68.0 to 64.4 °F (20 to 18 °C), respectively. The newly emerged larvae assume a demersal existence (Smith
et al.,
1980). The yolk sac larval stage is completed in about 8 to 12 days, during which time the larvae move downstream to rearing grounds (Kynard and Horgan, 2002). During the first half of their migration downstream, movement occurs only at night. During the day, larvae use benthic structure (
e.g.,
gravel matrix) as refuge (Kynard and Horgan, 2002). During the latter half of migration, when larvae are more fully developed, movement to rearing grounds occurs during both the day and night.

Larval Atlantic sturgeon (
i.e.,
less than 4 weeks old, with total lengths (TL) less than 30 mm; Van Eenennaam
et al.,
1996) are assumed to inhabit the same areas where they were spawned and live at or near the bottom (Ryder, 1888; Smith
et al.,
1980; Bain
et al.,
2000; Kynard and Horgan, 2002; Greene
et al.,
2009). The best scientific information available for behavior of larval Atlantic sturgeon is described from hatchery studies. Upon hatching, larvae are nourished by the yolk sac, are mostly pelagic (
e.g.,
exhibit a “swim-up and drift-down” behavior in hatchery tanks; Mohler, 2003), and move away from light (
i.e.,
negative photo-taxis; Kynard and Horgan, 2002; Mohler, 2003). Within days, larvae exhibit more benthic behavior until the yolk sac is absorbed at about 8 to 10 days post-hatching (Kynard and Horgan, 2002; Mohler, 2003). Post-yolk sac larvae occur in the water column but feed at the bottom of the water column (Mohler, 2003; Richardson
et al.,
2007).

The next phase of development, referred to as the juvenile stage, lasts months to years in brackish waters of the natal estuary (Holland and Yelverton, 1973; Dovel and Berggen, 1983; Waldman
et al.,
1996; Shirey
et al.,
1997; Collins
et al.,
2000; Secor
et al.,
2000; Dadswell, 2006; Hatin
et al.,
2007; ASSRT, 2007; Calvo
et al.,
2010; Schueller and Peterson, 2010). Juvenile rearing habitat is that habitat necessary for juveniles to grow, develop, and emigrate to the marine environment where they begin the subadult life stage, eventually maturing into adults. Juveniles occur in oligohaline waters (salinity of 0.5 to 5 ppt) and mesohaline waters (salinity of 5 to 18 ppt) of the natal estuary during growth and development. They will eventually move into polyhaline waters (salinity of 18-30 ppt), if available in the natal river estuary, before emigrating from the natal river estuary. Larger, presumably older,

juveniles occur across a broader salinity range than smaller, presumably younger, juveniles (Bain, 1997; Shirey
et al.,
1997; Haley, 1999; Bain
et al.,
2000; Collins
et al.,
2000; Secor
et al.,
2000; Hatin
et al.,
2007; McCord
et al.,
2007; Munro
et al.,
2007; Sweka
et al.,
2007; Calvo
et al.,
2010).

The distribution of Atlantic sturgeon juveniles in the natal estuary is a function of physiological development and habitat selection based on water quality factors of temperature, salinity, and DO, which are inter-related environmental variables. In laboratory studies with salinities of 8 to 15 ppt and temperatures of 12 and 20 °C (53.6 and 68 °F), juveniles less than a year old (also known as young-of-year [YOY]) had reduced growth at 40 percent DO saturation, grew best at 70 percent DO saturation, and selected conditions that supported growth (Niklitschek and Secor, 2009 I; Niklitschek and Secor, 2009 II). Similar results were obtained for age-1 juveniles (
i.e.,
greater than 1 year old and less than 2 years old), which have been shown to tolerate salinities of 33 ppt (
e.g.,
a salinity level associated with seawater), but grow faster in lower salinity waters (Niklitschek and Secor, 2009 I; Allen
et al.,
2014). For the conditions tested, the best growth for both age groups occurred at DO concentrations greater than 6.5 mg/L (
e.g.,
70 percent DO saturation with salinity of 8 to 15 ppt and temperature of 12 and 20 °C). While specific DO concentrations at temperatures considered stressful for Atlantic sturgeon are not available, instantaneous minimum DO concentrations of 4.3 mg/L protect survival of shortnose sturgeon at temperatures greater than 29 °C (84.2 °F) (EPA, 2003). However, data from Secor and Niklitschek (2001) show that shortnose sturgeon are more tolerant of higher temperatures than Atlantic sturgeon, and the “high temperature” for Atlantic sturgeon is actually considered 26 °C (78.8 °F) (Secor and Gunderson, 1998).

Once suitably developed, Atlantic sturgeon leave the natal estuary and enter marine waters (
i.e.,
waters with salinity greater than 30 ppt); this marks the beginning of the subadult life stage. In the marine environment, subadults mix with adults and subadults from other river systems (Bowen and Avise, 1990; Wirgin
et al.,
2012; Waldman
et al.,
2013; O'Leary
et al.,
2014). Atlantic sturgeon travel long distances in marine waters, aggregate in both oceanic and estuarine areas at certain times of the year, and exhibit seasonal coastal movements in the spring and fall (Vladykov and Greeley, 1963; Oliver
et al.,
2013).

The exact spawning locations for Gulf of Maine, New York Bight, Chesapeake Bay, Carolina, and South Atlantic DPS Atlantic sturgeon are unknown but inferred based on the location of freshwater, hard substrate, water depth, tracking of adults to upriver locations and the behavior of adults at those locations, historical accounts of where the caviar fishery occurred, capture of YOY and, in limited cases, capture of larvae and eggs. Spawning sites at multiple locations within the tidal-affected river likely help to ensure successful spawning given annual changes in the location of the salt wedge.

Public Comments and Our Responses

We requested comments on the proposed rule to designate critical habitat for the Gulf of Maine, New York Bight, Chesapeake Bay DPSs of Atlantic sturgeon (81 FR 35701; June 3, 2016) and on the proposed rule to designate critical habitat for the Carolina and South Atlantic DPSs of Atlantic sturgeon (81 FR 36077; June 3, 2016) for a 90-day period. Following requests from the public, we re-opened the public comment period for an additional 15 days (81 FR 66911; Sept. 29, 2016), for a total comment period of 105 days. Five public hearings were also held on the following dates and in the following locations:

1. Thursday, July 21, 2016, 3 to 5 p.m., Gloucester, Massachusetts.

2. Thursday, July 21, 2016, 6 to 8 p.m., Gloucester, Massachusetts.

3. Monday, June 20, 2016, 7 to 9 p.m., Brunswick, Georgia.

4. Tuesday, June 21, 2016, 7 to 9 p.m., Charleston, South Carolina.

5. Thursday, June 23, 2016, 7 to 9 p.m., Morehead City, North Carolina.

In addition to the public hearings, during which substantive comments on the proposed designations could be provided by the public, we held a public informational meeting prior to each public hearing in Massachusetts, Georgia, South Carolina, and North Carolina. We also held public informational meetings in Annapolis, Maryland on July 13, 2016, and in Portland, Maine on July 18, 2016. These informational meetings reviewed the purpose of designating critical habitat and answered procedural questions. We did not accept public comment or answer substantive questions about the areas proposed for designation at the informational meetings; rather, we provided information on the public comment process. To further facilitate public participation, the proposed rules were made available on our regional Web pages and comments were accepted during public hearings, and via standard mail, facsimile, and through the Federal eRulemaking portal. In addition to the proposed rules, the correction notice for the proposed rule for the Carolina and South Atlantic DPSs, maps of the proposed critical habitat units, and the DIAs supporting our conclusions under section 4(b)(2) of the ESA were made publicly available.

Twenty-one people attended the public hearings for the proposed rule to designate critical habitat for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs of Atlantic sturgeon, either in-person or via telephone, and we received 1,577 responses to the request for public comments on the proposed rule and supporting documents through
Regulations.gov
and by mail, including over 1,000 form letters. Approximately 40 people attended the public hearings for the proposed rule to designate critical habitat for the Carolina and South Atlantic DPSs of Atlantic sturgeon, and 354 public comments were received on the proposed rule and supporting documents.

We reviewed all comments received for substantive issues relevant to the proposed critical habitat rules. Some comments resulted in changes between the proposed and final designation. Changes between the proposed designations and final designation are highlighted in the “Summary of Changes From the Proposed Rules” section of this rule. The relevant public comments received, both written and oral, are addressed below. We have responded to the comments received on the proposed rule for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs of Atlantic sturgeon separately from our responses to the comments received on the proposed rule for the Carolina and South Atlantic DPSs of Atlantic sturgeon because it would be difficult for a commenter to identify his or her individual comment and our response if we merged the comment responses. However, we have assigned comments to major issue categories and, where appropriate, have combined similar comments from multiple members of the public or referenced the response to identical comments received on both proposed rules. We received some comments related to the listing and DPS delineation and comments critical of our final rule Implementing Changes to the Regulations for Designating Critical Habitat (81 FR 7414; February 11, 2016); those comments are not relevant to this

critical habitat designation and are not addressed below.

Comments on the Gulf of Maine, New York Bight, and Chesapeake Bay DPS Proposed Critical Habitat Designations (81 FR 35701; June 3, 2016)

Comments on Geographical Area Occupied

Comment 1:
A commenter stated that we have not provided any evidence that Atlantic sturgeon occupied the Susquehanna River at the time the species was listed, or at any time in recent history. They stated that the most recent sighting of Atlantic sturgeon occurred in 1987, nearly 25 years before the species was listed in 2012, and that sighting occurred near the mouth of the Susquehanna River rather than in the Susquehanna River. The commenter noted that Exelon monitored the Susquehanna River for sonic transmitter tagged sturgeons from other river systems (Delaware River, Potomac River) during 2010 and 2011 with fixed station acoustic telemetry receivers, and no tagged Atlantic sturgeon were recorded in the Susquehanna River in either year. In addition, they stated that Atlantic sturgeon have not been caught in the Conowingo Dam fish lift in 44 years of fish lift operations, there have been no reports of anglers catching Atlantic sturgeon or observations of breaching Atlantic sturgeon in the Susquehanna River, and there are no records for Atlantic sturgeon in the Susquehanna River in the USFWS tagging database or the Maryland Department of Natural Resources reward program database.

Our Response:
Our regulations at 50 CFR 424.02 define “geographical area occupied by the species” as “An area that may generally be delineated around species' occurrences, as determined by the Secretary (
i.e.,
range). Such areas may include those areas used throughout all or part of the species' life cycle, even if not used on a regular basis (
e.g.,
migratory corridors, seasonal habitats, and habitats used periodically, but not solely, by vagrant individuals).” The range of each DPS is informed by numerous lines of evidence including the life history of Atlantic sturgeon, tagging, tracking, and genetic analyses. Often at the time of designating critical habitat, we do not have detailed information or the same level of detail for every part of the species' range. However, the absence of collection or sighting of Atlantic sturgeon in any part of their range does not equate to absence of Atlantic sturgeon. Atlantic sturgeon can be difficult to detect when present in marine and estuarine waters because they are benthic fish, spending most of their lives well below the water surface, they do not school, they move within the estuary, and subadults and adults spend only part of the year in estuarine waters.

There has been very little effort to detect the presence of Atlantic sturgeon in the Susquehanna River in recent times. Receivers were placed in the Susquehanna River to detect acoustically tagged Atlantic sturgeon in 2010 and 2011 but, at that time, we made it clear that an absence of detections was not confirmation of absence of the species in the river, given the low number of Atlantic sturgeon that were acoustically tagged and the limited number of receivers placed in the river below Conowingo Dam.

Fish behavior rather than fish abundance influences whether a sturgeon enters a fish lift that was designed for a different fish species. Therefore, absence of Atlantic sturgeon in the fish lift also does not equate to absence of Atlantic sturgeon in the river below a dam. Many of the rivers for which we have more abundant documentation of Atlantic sturgeon presence also have dams with fish lifts (
e.g.,
Connecticut, Penobscot, and Saco Rivers), and only one Atlantic sturgeon has been observed and documented in a fish lift (at the Holyoke Dam in the Connecticut River (ASSRT 2007)).

The Maryland Reward Program relied upon reports of Atlantic sturgeon incidentally caught in fishing gear. The Program operated when directed fishing for, and incidental capture of, Atlantic sturgeon was prohibited and when abundance of Atlantic sturgeon was unknown and estimated to be low (thus later necessitating listing under the ESA). The lack of reported captures of Atlantic sturgeon in the Susquehanna can be explained by any number of factors including whether: Fishing was occurring in the Susquehanna when Atlantic sturgeon were present, the gear type fished was conducive to catching Atlantic sturgeon, or the fisherman reported the capture. Similarly, to assess whether the absence of USFWS tagging database records for Atlantic sturgeon captures in the Susquehanna reflects absence of Atlantic sturgeon in the Susquehanna River, a measure of the amount of effort to search for, capture, and tag Atlantic sturgeon in the Susquehanna River must be provided. Based on the best scientific information available, there was no directed effort to search for, capture, and tag Atlantic sturgeon in the Susquehanna River. Therefore, the absence of records in the USFWS tagging database does not inform the presence or absence of Atlantic sturgeon in the river.

The lack of evidence for Atlantic sturgeon presence in the Susquehanna based on the scientific studies or recreational fishing in the river is more likely the result of methods and gear that do not effectively capture sturgeon. Sturgeon tend to sink rather than float when exposed to electroshocking (Moser
et al.,
2000). Electroshocking conducted to retrieve other fish species often does not result in detection of Atlantic sturgeon because the electric current may only penetrate a few feet from the surface of the water and not reach the bottom where sturgeon are most likely to occur. Although some sturgeon have been detected during electrofishing for other species, electroshocking is not an effective means for detecting sturgeon presence. Gillnet gear is only effective when selective for the size of sturgeon present, and sturgeon can get snagged on recreational hook gear but do not typically take a hook. Therefore, creel surveys of recreational fisheries are unlikely to provide evidence of sturgeon presence, particularly when the recreational fisheries are targeting fish species dissimilar to sturgeons (
e.g.,
in size, feeding characteristics).

Since the listing of the Chesapeake Bay DPS in 2012, increased effort to detect Atlantic sturgeon in the Pamunkey, Nanticoke, and Rappahannock Rivers has led to the discovery of Atlantic sturgeon spawning populations and sturgeon presence that were undetected before the listing. These include a spawning population in the Pamunkey River (Hager
et al.,
2014; Kahn
et al.,
2014), a likely spawning population in the Nanticoke River, and detection of Atlantic sturgeon in the Rappahannock River.

Comment 2:
An industry trade group stated we inappropriately delineated the “geographical area occupied” by the species as the entire “aquatic habitat (
e.g.,
below the high tide line)” of inland freshwater areas that are currently accessible to the Atlantic sturgeon. These commenters stated that we inappropriately included not just areas where the species has actually been located, but instead we also included wider areas around the species' occurrences and areas that may be used only temporarily or periodically by the species. They stated that “areas identified as occupied include vast areas where there is no evidence the species even occurs, much less occupies.” The commenter states that the Services' Consultation Handbook provides that occupied critical habitat is “critical habitat that contains

individuals of the species at the time of the project analysis.”

Our Response:
Our regulations at 50 CFR 424.02 define the geographical area occupied by the species as an area that may generally be delineated around species' occurrences (
i.e.,
range), and this may include those areas used throughout all or part of the species' life cycle, even if they are not used on a regular basis (
e.g.,
migratory corridors, seasonal habitats, and or habitats used periodically, but not solely by vagrant individuals). This is consistent with past critical habitat designations
(e.g.,
Final Rule Designating Critical Habitat for Threatened Elkhorn and Staghorn Corals (73 FR 72210; November 26, 2008): “We have long interpreted `geographical area occupied' in the definition of critical habitat to mean the range of the species at the time of listing (45 FR 13011; February 27, 1980)”). The geographical area occupied as specified in this designation meets the regulatory definition, and our application of the term “geographical area occupied” to Atlantic sturgeon is appropriate. As the court in
Arizona Cattle Growers Ass'n
v.
Salazar
(606 F.3d 1160, 1164 (9th Cir. 2010)) held, “[d]etermining whether a species uses an area with sufficient regularity that it is `occupied' is a highly contextual and fact-dependent inquiry. Cf.
Cape Hatteras Access Pres. Alliance
v.
United States DOI,
344 F. Supp. 2d 108, 119-20 (D.D.C. 2004). Relevant factors may include how often the area is used, how the species uses the area, the necessity of the area for the species' conservation, species characteristics such as degree of mobility or migration, and any other factors that may bear on the inquiry.” In claiming that the 1998 Consultation Handbook provides that occupied critical habitat is that which is occupied by individuals of the species at the time of a project analysis, the commenter did not include the entire discussion about occupied critical habitat. As we explained more fully in our Handbook, “[a] species does not have to occupy critical habitat throughout the year for the habitat to be considered occupied (
e.g.
migratory birds).” The court in
Arizona Cattle Growers
cited this language as appropriately recognizing that “a species need not be present continuously for habitat to be considered “occupied.” 606 F.3d at 1165. The court rejected a narrow interpretation of “occupied” based solely on documented ”residence” of individual animals, holding that “[w]here data are inconclusive or where habitat is used on a sporadic basis, allowing the FWS to designate as `occupied' habitat where the species is likely to be found promotes the ESA's conservation goals and comports with the ESA's policy of “institutionalized caution” (
Id.
at 1166-1167), and that “[t]he fact that a member of the species is not present in an area at a given instant does not mean the area is suitable only for future occupancy if the species regularly uses the area” (
Id.
at 1167).

For Atlantic sturgeon, we identified the geographical area occupied based on the species' well-known anadromous life history, including returning to natal rivers to spawn, spawning behaviors, and habitat common to sturgeon species and verified for Atlantic sturgeon, as well as the need to protect spawning and reproductive habitat for population growth and conservation of the species, among other factors. Some portion of each river population returns to its natal river to spawn every year, and if spawning occurs and is successful, young sturgeon use the natal river to forage, develop and mature every year.

Comment 3:
A state agency stated there may be habitat features conducive for Atlantic sturgeon reproduction and recruitment in the Piscataqua, Salmon Falls, and Cocheco Rivers, but there was no evidence that Atlantic sturgeon have used New Hampshire estuaries and coastal rivers as spawning and nursery habitat from at least 35 years of surveys, studies, etc. The commenter stated that recent evidence from acoustical tagging (Micah Kieffer, USGS, personal communication, as cited in the comment) leads to the conclusion that sturgeons spend only brief periods in the Piscataqua River/Great Bay system during longer movements between the Merrimack and Kennebec Rivers. A fisherman similarly stated that in all of his fishing trips in the Piscataqua River over the course of 20-plus years, he had never encountered Atlantic sturgeon in the Piscataqua River, and he does not believe that Atlantic sturgeon spawning or juvenile rearing occurs in the Piscataqua, Salmon Falls, and Cocheco Rivers.

Our Response:
We disagree with these commenters' assertions that Atlantic sturgeon do not occur in these waterbodies. The Piscataqua River as well as the Cocheco and Salmon Falls Rivers downriver of their respective lowermost dams are part of the geographical area occupied by Atlantic sturgeon. Recent evidence of their presence includes detection of tagged Atlantic sturgeon (M.Kieffer, USGS, pers. comm.). Because the number of tagged Atlantic sturgeon represents only a fraction of the total number of sturgeon, and receivers for detecting tags are not in the rivers throughout the year, the number of Atlantic sturgeon detected in the Piscataqua is very likely less than the total number of Atlantic sturgeon that actually occur in the Piscataqua and as far upriver as the lowermost dams of the Cocheco and Salmon Falls Rivers.

We identified the Piscataqua River and portions of the Salmon Falls and Cocheco Rivers as a potential critical habitat area for the Gulf of Maine DPS because the physical features are present. We considered whether the identified area was essential to the conservation of the Gulf of Maine DPS and concluded that it was, given the capture of a large female Atlantic sturgeon with eggs, at the head-of-tide in the Salmon Falls River in South Berwick, Maine on June 18, 1990, thus demonstrating behavior consistent with spawning was occurring in the system. We also took into consideration the limited number of other rivers with spawning and rearing habitat in the Gulf of Maine DPS, the continuing threats to the DPS, the threats to the features of critical habitat, and the uncertainty for how much spawning and rearing habitat is necessary to recover the Gulf of Maine DPS. Together, this information supports our conclusion that the Piscataqua River, and portions of the Salmon Falls and Cocheco Rivers, are part of the geographical area occupied by the Gulf of Maine DPS and these areas are essential to the conservation of the Gulf of Maine DPS.

We are not surprised that there have been very few incidental captures of Atlantic sturgeon in fisheries or research surveys and studies conducted in the Piscataqua River. We know from other river systems that capture of any of the Atlantic sturgeon life stages can be difficult even when the proper gear for capturing Atlantic sturgeon is used, and used at the time and in the area where Atlantic sturgeon are likely to occur. Atlantic sturgeon populations in a number of rivers were considered extirpated at one point, only later to find that genetically unique populations were present (
e.g.,
the James River and York River systems, the Connecticut River, the Nanticoke River, and Marshyhope Creek).

Comment 4:
A representative for a power operation on the Hudson River stated that atypical passage or straying is not enough to constitute critical habitat, and critical habitat shall not include the entire geographical area which can be occupied by the threatened or endangered species.

Our Response:
We agree that it is inappropriate to designate the entire area occupied by a DPS as critical

habitat. However, we have not done that for any of the Atlantic sturgeon DPSs. The geographical area occupied by the New York Bight DPS of Atlantic sturgeon is a broad area that includes the Hudson River as far upriver as the Federal Dam near Albany, NY. The New York Bight DPS consists of all Atlantic sturgeon spawned in the watersheds that drain into coastal waters, including Long Island Sound, the New York Bight, and Delaware Bay, from Chatham, Massachusetts to the Delaware-Maryland border on Fenwick Island. The range of the DPS in marine waters extends from Labrador, Canada to Cape Canaveral, Florida, United States. The area of the Hudson River that we are designating as critical habitat is, therefore, a specific area within the much broader geographical area occupied by the DPS.

Comments on Physical or Biological Features (PBFs)

Comment 5:
A commenter stated the critical habitat designation for Atlantic sturgeon fails to identify any in-river habitats that are important aggregation areas for Atlantic sturgeon. They also stated that we designated in-river habitats where sturgeon congregate, presumably for resting and energy conservation, for both the southern DPS of green sturgeon, and for Gulf sturgeon, and it is likely that Atlantic sturgeon have a similar habitat requirement.

Our Response:
While there are similarities between all sturgeon species, there are also differences. The proposed rule and the Impacts Analysis and Biological Information Source Document summarized the literature describing spawning behavior for male and female Atlantic sturgeon. Briefly, male Atlantic sturgeon in spawning condition have been observed to stage in more saline waters of the coastal estuary before moving upriver once the water temperature reaches approximately 6 °C (43 °F). They may spend weeks moving upstream and downstream of the presumed spawning area(s) before moving back downriver to the lower estuary and residing there until outmigration in the fall (Smith
et al.,
1982; Dovel and Berggren, 1983; Smith, 1985; Bain, 1997; Bain
et al.,
2000; Collins
et al.,
2000; Hatin
et al.,
2002; Greene
et al.,
2009; Balazik
et al.,
2012; Breece
et al.,
2013). In contrast, spawning females move upriver when temperatures are closer to 12 to 13 °C (54 to 55 °F), return downriver relatively quickly, and may leave the estuary and travel to other coastal estuaries until outmigration to marine waters in the fall (Smith
et al.,
1982; Dovel and Berggren, 1983; Smith, 1985; Bain, 1997; Bain
et al.,
2000; Collins
et al.,
2000; Greene
et al.,
2009; Balazik
et al.,
2012; Breece
et al.,
2013).

The use of telemetry tags for Atlantic sturgeon and more widespread use of receiver arrays has provided new information on Atlantic sturgeon spawning behavior and whether or when staging occurs. In the James River, some males moved straight to the hypothesized spawning ground without any apparent staging period while others occurred downriver in brackish water during the summer before moving upstream in August or early September; still others occurred farther upriver for a period of time before the spawning period (Balazik and Musick, 2015). Given the various movement patterns, it is not clear to what extent staging occurs or, for those fish that do appear to stage, whether it is essential for successful reproduction. Therefore, we have not included specific staging areas as a physical or biological feature of Atlantic sturgeon critical habitat. However, we recognize new research may lead to better identification regarding whether, where, and when Atlantic sturgeon stage. Therefore, the feature addressing access includes open passage between the river mouth and spawning sites to support life history needs associated with reproduction such as staging, resting, or holding of spawning condition adults.

Comment 6:
Two commenters provided information on the presence of Atlantic sturgeon in the Hudson River and in Delaware Bay in proximity to sand waves, postulating that sand wave habitat provides the same function as deep holes provide for green and Gulf sturgeon, allowing Atlantic sturgeon to rest and feed during the spawning season. According to the commenters, in the Hudson River, sand waves were found in proximity to the Atlantic sturgeon spawning areas. Side scan sonar showed a high density of spawning size Atlantic sturgeon in sand wave habitat and no sturgeon in sand habitat without waves. A gill net set in proximity to the sand wave habitat had high catch rates of Atlantic sturgeon. Similarly, in the Delaware Bay, telemetry tagged Atlantic sturgeon were detected in high density in a relatively small area (18.8 acres) within, and bordering sand wave habitat. The commenters point out that habitat that provides for rest or cover has been identified as an essential feature for other fish species.

Our Response:
The commenters provide new, intriguing information for a possible association between Atlantic sturgeon and sand wave habitat. When designating critical habitat, we do not have to know exactly why the listed species occurs in an area. We do, however, need to identify physical or biological features that support the life history needs of the species. The commenters postulate that the sand waves provide resting and feeding areas for Atlantic sturgeon during spawning and feeding in the lower estuary. However, no information was provided to support this theory and the literature does not point toward evidence of feeding or resting during spawning. On the contrary, available references suggest female Atlantic sturgeon make rapid upriver and downriver movements during spawning and can completely leave the spawning estuary and travel to other estuarine environments, presumably for foraging. Males move upriver and downriver of the spawning area during the spawning season, and then move downriver at the end of the spawning season presumably to rest and forage before leaving the spawning estuary in the fall. At this time, we do not have sufficient information to determine what life history needs sand waves may support.

Sand waves are a common feature of the Hudson River and Delaware Bay as well as other rivers and bays (
e.g.,
see information for the Delaware Bay Benthic Mapping Project at
http://www.dnrec.delaware.gov/coastal/dnerr/documents/benthic4plet.pdf,
and Levin
et al.,
1992). The mapping images provided by the commenter for the Hudson River depict dynamic wave habitat and approximate spawning area for Atlantic sturgeon. Wave habitat is depicted as occurring in a number of areas. Some of these are in proximity to spawning areas and some are not. Similarly, the information provided by the commenter for Delaware Bay depicts sand wave habitat in proximity to an observed aggregation of Atlantic sturgeon. However, no information is provided for Atlantic sturgeon presence in other areas of the Bay where sand wave habitat also occurs and does not occur. Therefore, the information provided and the other available information (
i.e.,
published literature) do not support the commenter's position that sand waves in the Hudson River and Delaware Bay support the life history needs of the New York Bight DPS, and we have not included sand waves as a physical or biological feature of critical habitat for the New York Bight DPS of Atlantic sturgeon.

Comment 7:
A commenter stated that while the proposed designation includes soft-bottom habitats for juvenile foraging and development, it fails to expressly recognize the need to protect soft-bottom areas that serve as

resting and feeding habitats for spawning adults. The commenter called upon us to designate soft-bottom areas of the Hudson River for resting and feeding habitats for spawning adults, particularly the areas with sand waves, as critical habitat.

Our Response:
Soft-bottom areas of the Hudson River are part of the Hudson River critical habitat unit based on the best available scientific information that soft bottom substrates and the transitional salinity zone are needed for juvenile rearing. We are not aware of any information that indicates Atlantic sturgeon spawning adults feed or rest in spawning areas, and the commenters did not provide any such information. Available references indicate spawning female Atlantic sturgeon make rapid upriver movements to spawning areas and quickly depart spawning areas while males move upriver and downriver of the spawning area during the spawning season. If new information on the use of soft substrate by spawning adults becomes available, it will be considered by Federal agencies assessing the effects of proposed actions on the Hudson River critical habitat, and by us as the consulting agency in ESA section 7 consultations. More details of our consideration of sand wave habitat as a physical or biological feature is provided in our response to Comment 6. As noted there, the best scientific information available does not currently support sand waves as a physical or biological feature for Atlantic sturgeon critical habitat.

Comment 8:
An industry trade group asserted that we must revise our proposed designation to explain how each specific critical habitat unit to be designated contains the PBFs essential to the conservation of the species, suggesting that our approach should be the same as that taken in the designation of critical habitat for the Southern DPS of green sturgeon (74 FR 52300; October 9, 2009). They also suggested our proposed designation is overly broad, improperly used “ephemeral reference points,” and is unsupported by facts or science. The commenters suggested we identified and proposed to designate sweeping areas of occupied habitat that undoubtedly capture many areas that do not have, and likely never will have, physical or biological characteristics essential for the conservation of the species, noting that the designations cover manmade areas that they state are not important to the species, such as “manmade features” below the mean high water mark that cannot or would not be accessed by the species (
e.g.,
outfalls, enclosures, quays) and industrialized areas used by ocean-going vessels. One commenter suggested it appeared we had merely designated entire rivers from the confluence of the Atlantic Ocean back to either some major tributary or some large impoundment or impassable boundary upstream. Several commenters suggested that areas should not be designated as critical habitat because environmental conditions in certain stretches of rivers are poor and would not support the PBFs. Similarly, other commenters stated we had failed to limit the mapped areas in our proposed designation to areas where we believe the PBFs occur.

Our Response:
We disagree. As we explained in our final rule, Implementing Changes to the Regulations for Designating Critical Habitat (81 FR 7414; February 11, 2016), in each designation we will identify specific areas of critical habitat “at a scale determined by the Secretary to be appropriate.” We are not required to make determinations at an infinitely fine scale, and we need not determine that each square inch, square yard, acre, or even square mile independently meets the definition of critical habitat. We have discretion to determine the appropriate scale for the analysis, which is informed by, among other things, the life history of the species, the scales at which data are available, and biological or geophysical boundaries (such as watersheds). Our regulations at 50 CFR 424.02 also indicate that PBFs may be ephemeral or dynamic, and we may designate areas with ephemeral or dynamic PBFs if the other applicable requirements of critical habitat designations are met, and if there are documented occurrences that a particular habitat type is in the area and there is a reasonable expectation of that habitat occurring again (81 FR 7414; February 11, 2016). As we acknowledged in the proposed rule, there are large areas of most rivers where data are still lacking. The available data also represent a snapshot in time, and the exact location of a PBF may change over time (
e.g.,
water depth fluctuates seasonally, as well as annually, and even hard substrate may shift position). Although the PBFs may vary even at the same location, if any of the available data regarding a particular PBF fell within the suitable range (
e.g.,
salinity of 0-0.5 ppt or hard substrate [gravel, cobble, etc.]), we considered that the essential PBF is present in the area. When data were not available for certain rivers or portions of occupied rivers, we used our general knowledge of Atlantic sturgeon spawning and applied river-specific information to determine the location of PBFs essential to spawning. Smaller specific areas within each unit could not be identified because the submerged nature of the essential PBF, the limits of available information on the distribution of the PBFs, the varying distribution of the PBFs from time to time, and limits on mapping methodologies make it infeasible to define the specific areas containing the PBFs more finely than described in this rule. The presence of manmade structures that do not provide the PBFs within a specific area being designated as critical habitat does not render the boundaries of the specific area invalid; we have explained that the PBFs must be in a project area for it to function as critical habitat. While we agree that manmade structures themselves (
e.g.,
an outfall pipe, dock, pier, navigational buoy) cannot and do not contain the PBFs and therefore are not part of the critical habitat designation, the mere presence of such a manmade structure in an area does not mean that the area does not contain one or more PBFs or that these areas are not important to the species. We have clarified the point in regulatory text that manmade features that do not provide the PBFs are not essential to the species and are not included in critical habitat. We believe our designation is consistent with our regulations and based on the best scientific information available for Atlantic sturgeon DPSs.

Comment 9:
Two commenters stated we failed to consider in a complete and meaningful way, the role certain aspects of aquatic chemistry play on determining whether a river has suitable spawning habitat. The commenters suggested we should have considered pH and levels of calcium and magnesium ions. They suggest these chemical characteristics can determine whether Atlantic sturgeon will spawn in a particular reach of river, and thus, it is crucial that these features are given special management consideration in future section 7 consultations and, if need be, protected accordingly.

Our Response:
The literature on Atlantic sturgeon has not typically reported pH, calcium, and magnesium levels for rivers where Atlantic sturgeon spawn. For example, in their review of essential Atlantic sturgeon spawning habitat in Virginia, Bushnoe
et al.
(2005) reported pH for waters of the James, York, Pamunkey, Mattaponi, and Rappahannock Rivers where they anticipated Atlantic sturgeon spawning could occur. However, with respect to other water parameters, they noted available water quality data for the James River measured calcium carbonate concentration, not calcium

concentration, as an indicator of hardness. Therefore, they could not directly compare the measured calcium carbonate concentrations with reported calcium concentrations measured in other rivers where Atlantic sturgeon spawn. Conductivity was measured in the Rappahannock River, but neither hardness or conductivity measurements were available for the Pamunkey River or Mattaponi River. Recent publications regarding Atlantic sturgeon spawning for the Chesapeake Bay DPS of Atlantic sturgeon (
e.g.,
Balazik
et al.,
2012; Hager
et al.,
2014) do not include measures of water pH, calcium, or magnesium in spawning areas.

We considered the information provided by the commenters in the report they provided with their comments and references cited within that report. Unfortunately, the report itself does not provide any new information regarding pH and levels of calcium and magnesium ions. The report mentions a 1976 study that indicated spawning of the European Atlantic sturgeon had been successful in the Rione River of the Russian Caucasus when the pH ranged from 7.4-7.6. The report also states that a pH level of 6.8-7.7 is acceptable to various species of sturgeon (Holcik
et al.,
1989), but continues to state there is no specific research on pH levels appropriate for Atlantic sturgeon. Beyond this, no further conclusions regarding pH and Atlantic sturgeon were made. The provided report also briefly mentioned calcium and magnesium ions. It states: “Salinity was 0.4 psu, which is on the high side of Ca[lcium] and M[a]g[nesium] ion levels present in rivers where Gulf Sturgeon spawn successfully (Ken Sulak, pers. comm. to B. Kynard, 15 Aug 2016). Specific acceptable levels of salinity for gametes and eggs of Atlantic sturgeon are not known and are not discussed by the Atlantic Sturgeon Status Review Team (ASSRT 2007) or in the preamble to NMFS' proposed designation. However, based on Gulf Sturgeon tolerance and Cherr and Clark (1985), the levels of Ca[lcium] and M[a]g[nesium] ions in the Ocklawaha River should not be a problem for egg fertilization or egg rearing of sturgeons.” Beyond this discussion of calcium and magnesium, no further information is provided regarding the relationship of these ions to successful spawning of Atlantic sturgeon. The report provided by the commenters also cited additional literature that may discuss these water quality parameters. However, we attempted to acquire these references and were unable to because they were not readily available to the public. Thus, we determined there was not enough information for us to include the specific water quality parameters mentioned by the commenter as essential PBFs for any DPS of Atlantic sturgeon.

Comment 10:
An association of municipal wastewater agencies stated that the preamble of the proposed rule for the Gulf of Maine, New York Bight, and Chesapeake Bay DPS properly explains that “specific oxygen concentration and temperature values are provided as examples and guidance” but the proposed rule omits this key language from the regulatory text. The commenter believes the regulatory text should include this explanation or, alternatively, the examples of the water feature characteristics should be removed from the final rule or be made more specific to the spawning and subsequent stages of development of the Atlantic sturgeon in the specific habitats described in the proposed rule.

Our Response:
We do not provide explanations of the regulations in the regulatory text. The use of “
e.g.”
in the regulatory text informs the reader that the DO level and water temperature are provided only as guidance, and these are not the only values for either DO or temperature that are suitable for all Atlantic sturgeon age classes addressed by the PBFs.

Comment 11:
A commenter stated the proposed rule for the Carolina and South Atlantic DPSs also frames the features as “optimal” and “suboptimal” and recommended that we “revise Part (a)(4)(iii) of the proposed rule for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs” to frame the features as optimal and suboptimal.

Our Response:
Upon reading the comment, we realized that framing the example of dissolved oxygen and temperature values as “optimal” and “suboptimal” can be misinterpreted as establishing specific, exclusive values. Since these values were meant to be examples of the numerous possible combinations of dissolved oxygen, water temperature, and salinity essential to Atlantic sturgeon conservation, we did not revise the language for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs of Atlantic sturgeon to frame the features as “optimal” and “suboptimal.” This is because there is not one single DO level or temperature range that is best for Atlantic sturgeon in terms of habitat avoidance. We did revise the language for the Carolina and South Atlantic DPSs of Atlantic sturgeon by replacing the terms “optimal” and “suboptimal.” The new phrases convey that the examples provide context, but do not establish static, exclusive values for the essential physical feature.

The dissolved oxygen levels and water temperature values set forth in the proposed rules for the Atlantic Sturgeon DPSs were examples based on the best available information for conditions in different rivers occupied by Atlantic sturgeon and observed responses of sturgeon to these variables. Water quality factors of temperature, salinity and dissolved oxygen are inter-related environmental variables. Dissolved oxygen concentrations in water can fluctuate given a number of factors including water temperature (
e.g.,
cold water holds more oxygen than warm water) and salinity (
e.g.,
the amount of oxygen that can dissolve in water decreases as salinity increases). This means that, for example, the dissolved oxygen levels that support growth and development will be different at different combinations of water temperature and salinity. Similarly, the dissolved oxygen levels that we would expect Atlantic sturgeon to avoid would also vary depending on the particular water temperature and salinity. As dissolved oxygen tolerance changes with age, the conditions that support growth and development and likewise, the dissolved oxygen levels that would be avoided, change. This combination of factors makes it such that we cannot identify a single set of dissolved oxygen, water temperature and/or salinity conditions as optimal or suboptimal for any of the DPSs.

Like salinity and dissolved oxygen, water temperature fluctuates in the dynamic rivers and estuaries used by Atlantic sturgeon. The scientific literature for Atlantic sturgeon does not always include the water temperature where Atlantic sturgeon are detected or captured. There may also be differences in temperature tolerance of Atlantic sturgeon that originate from different rivers, and differences in temperature tolerance within the same river depending on the life stage. Therefore, while we generally know the ranges of water temperature and dissolved oxygen in which Atlantic sturgeon occur, we cannot identify a single “best” water temperature or dissolved oxygen level for all Atlantic sturgeon, in all rivers, under all circumstances.

We stated in the preamble of the proposed rule for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs that, “Specific areas designated as critical habitat based on the four features are not expected to have water with oxygen concentration of 6 mg/L and the specific water temperatures at all times and within all parts of the

area.” We similarly stated for the example in the proposed rule for the Carolina and South Atlantic DPSs of Atlantic sturgeon that, “Appropriate temperature and oxygen values will vary interdependently, and depending on salinity in a particular habitat.” Thus, we believe the terms “optimal” and “suboptimal” inadvertently conveyed a different meaning.

Comment 12:
A commenter recommended that we revise the guidance for DO concentrations and temperature values provided in the proposed rule to be consistent with existing U.S. Environmental Protection Agency Clean Water Act water quality criteria applicable to the Chesapeake Bay Watershed. The commenter further stated the proposed regulatory language establishing a DO concentration of 6 mg/L and a maximum temperature of 30 °C for juvenile rearing habitat is inconsistent with existing water quality criteria. The commenter also stated that the proposed rule should evaluate and address existing conditions in the waters for the features which will dictate where to designate critical habitat. This framework will provide a necessary reference for both the agency and commenters from which the true implications of the proposed habitat components can be evaluated. For example, the proposed rule provides that temperature between 13 °C to 26 °C is optimal for spawning habitat, but there is no indication of how that temperature range compares to the ambient temperature of the waters themselves. In other words, does the proposed critical habitat meet the habitat component for temperature most of the time, some of the time, etc. Second, the proposed rule must include a natural condition provision to reflect natural instream temperature and DO levels which are outside of the temperature and DO features in the proposed rule. Where ambient temperature and/or DO is outside of these levels, the natural condition must control. Any regulatory requirements must be targeted toward the natural condition and not critical temperature/dissolved oxygen elements that are not naturally present.

Our Response:
The water quality features are a physical feature essential to the corresponding Atlantic sturgeon DPSs. As discussed in our response to Comment 11, because DO and temperature vary interpedently based on local environmental conditions, the DO and temperature values provided in the proposed rules are provided as examples only. For example, the earliest life stages are the most sensitive to DO levels. Therefore, earlier life stages (
e.g.,
juveniles) may avoid areas based on one DO level while older life stages (
e.g.,
subadults or adults) may avoid areas based on a different DO level. The example provided in the regulatory text in the proposed rule for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs of Atlantic sturgeon is just one example. We have not included a framework for each critical habitat area or a natural condition provision. However, we agree that these should be considered when Federal agencies are determining whether a proposed Federal agency action may affect designated critical habitat for the Atlantic sturgeon DPSs, and considered by us when we are consulting on Federal agency actions. See our responses to Comments 83, 84 and 85 for more information on the water quality feature for the Carolina and South Atlantic DPSs of Atlantic sturgeon.

Comments on Special Management Considerations or Protection

Comment 13:
A commenter stated the proposal does not specify what “special management considerations or protections” are appropriate or necessary for the conservation of Atlantic sturgeon in all and/or each specific DPS. Given the areal extent of the proposed designation and the potential for consultation on numerous and varied actions (water use, wastewater discharges, dredging, etc.), the final rule needs to be more specific regarding the special management considerations or protections that may be required for all or specific DPSs.

Our Response:
Special management considerations or protections are the methods or procedures useful in protecting the PBFs essential to conservation of listed species. We provided information in the proposed rule for why the PBFs essential to the conservation of each DPS may require special management or protection. This provision of a designation does not establish measures that may be recommended or required during section 7 consultation, such as RPMs and terms and conditions. Our impacts analyses and 4(b)(2) report describe the types of measures that might be required to address adverse impacts to the PBFs for federal actions expected to require consultation.

Comment 14:
An industry trade group believes we failed to provide any assessment of current management or protections in place and whether those are adequate for the conservation of the Atlantic sturgeon. The commenters claim we must consider whether any of the proposed critical habitat units are presently under special management or protection for Atlantic sturgeon. The commenters acknowledge we have identified a number of initiatives that could protect Atlantic sturgeon but believe we must actually assess these initiatives to determine whether they are sufficient and determine what further management actions may benefit from critical habitat designation. The commenters go on to state we should consider each feature and specific area proposed and assess current management measures in place to make an actual determination as to whether special management may be needed in the reasonably foreseeable future, and if so, what that management would be, and how the critical habitat designation would further that management. The commenters conclude that our discussion of special management considerations is limited to general discussion regarding how barriers, water withdrawals, and dredging can generally affect water flow, quality, and depth and/or alter hard substrate, and that we have made non-specific assertions that special management for the essential PBFs may be required “as a result of global climate change.”

Our Response:
We disagree. When determining whether PBFs may require special management considerations or protection, we do not base our decisions on whether management is currently in place or whether that management is adequate (81 FR 7414; February 11, 2016). In
Center for Biological Diversity
v.
Norton,
240 F.Supp. 2d 1090, 1096-1100 (D. AZ, 2003), the court rejected reading the ESA to mean that if adequate management or protections are already in place, then an area cannot meet the definition of critical habitat because special management considerations or protections are not required (“Defendant's construction of `critical habitat' also adds the term `additional' to the statute. As Defendant stated in its final rule, `
Additional
special management is not required if adequate management or protection is already in place. . .' There is absolutely nothing in § 1532, or its implementing regulations, to support Defendant's inclusion of `additional.' As such, Defendant's construction of the `critical habitat' definition is impermissible and contrary to law.”) Additionally, we are not required to determine if a PBF currently requires special management considerations, or to determine what that management would be, and how critical habitat designation would further that management. We are only required to make a determination that a PBF
may
require special management

considerations or protection (81 FR 7414; February 11, 2016). Consequently, we assessed the need for special management considerations for each PBF in the proposed rule and identified numerous actions or natural factors that could adversely impact each PBF, as is required by the ESA (“Because the emphasis in the requirement is on the word `may,' the evidence shown by the Service supports the reasonable conclusion that
some
special management considerations or protection may be needed in the future to protect the sea ice habitat PCE [primary constituent element]. However, neither the Service nor the ESA have to be the vehicles by which the procedures or actions involved in the considerations or protection are accomplished. The Service has shown that someday, not necessarily at this time, such considerations or protection
may
be required. In other words, the Service has shown that it is within the realm of possibility that such considerations or protection may be needed now or in the future. Furthermore, the Service does not have to identify the source of such considerations or protection, merely that the considerations or protection may be necessary in the future. For example, the evidence in the record showing that sea ice is melting and that it will continue to melt in the future, perhaps at an accelerated rate, is more than enough proof that protection
may
be needed at some point” (
Alaska Oil and Gas Ass'n
v.
Salazar,
916 F. Supp. 2d 974, 990-992 (D. AK 2013), (Reversed on other grounds and remanded by
Alaska Oil & Gas Ass'n
v.
Jewell,
815 F.3d 544 (9th Cir. 2016)).

We also disagree with the commenters' characterization that we made non-specific assertions regarding the special management needs of the PBFs that may be necessary as a result of global climate change. The proposed rule specifically identifies the impact from global climate change's impacts to water temperature and DO, as potential threats to the survival and recovery of Atlantic sturgeon in the southeastern United States.

Comment 15:
A commenter asked if the objective of the special management considerations or protections is to create optimal habitat, specifically, to create the physical features described in § 226.225(a)(1) of the proposed rule, even if those features do not currently exist.

Our Response:
The answer to this question is no. Critical habitat is based on the presence of PBFs essential to the conservation of the listed species and which may require special management or protection. We only designate critical habitat when the PBFs essential to conservation of the listed species may require special management considerations or protections. If we identify PBFs essential to the listed species but those features do not require special management or protection, then we do not designate critical habitat based on those PBFs.

The purpose of designating critical habitat is to prevent the destruction or adverse modification of the habitat as a result of Federal activities. Section 7(a)(1) of the ESA requires Federal agencies to use their authorities in furtherance of the purposes of the ESA (
i.e.,
aid in the conservation of listed species). However, there is not a requirement that Federal agency actions improve or create habitat for ESA-listed species.

Comment 16:
Commenters requested that we include language to address known, significant, and growing uses that will adversely impact Atlantic sturgeon habitat in the Hudson River.

Our Response:
For critical habitat designations we identify activities that may necessitate special management or protection of the PBFs. We have provided this information for the PBFs identified for the critical habitat for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs. We cannot foresee every activity that would necessitate special management or protection of the PBFs. However, we believe the list of activities provided by us is comprehensive enough to provide adequate notice on which activities may affect critical habitat. The impact of Federal agency actions on the critical habitat features are assessed through ESA section 7 consultation.

Comment 17:
One commenter requested that we include “clear guidance for considering the effects of a changing climate on critical habitat designation for species recovery in the final rule.” They requested we consider “projected changes to salinity, temperature and DO, including changes in sea level rise.” They further requested that we document the extent that climate change was considered when assessing the need for the inclusion of currently unoccupied habitat in the final rule.

Our Response:
We acknowledge climate change is likely a factor contributing to the possible need for special management considerations or protection for the PBFs, and we recognize that climate change may affect the availability of some PBFs to sturgeon in some areas. As discussed in the response to comments for our regulations, Implementing Changes to the Regulations for Designating Critical Habitat (81 FR 7414; 7426; February 11, 2016), in those circumstances where the best scientific data available indicate that a species may be shifting habitats or habitat use, we may include specific areas accommodating these changes in a designation, provided we can explain why the areas meet the definition of critical habitat. No information is currently available, and none was provided by the commenter, that indicates any of the Atlantic sturgeon DPSs may be shifting habitats or habitat use in response to the effects of climate change. For example, Breece
et al.
(2016) projected how habitat use by adult Atlantic sturgeon of the Delaware River could shift in response to climate change, but did not provide evidence that Atlantic sturgeon are, or may be, shifting habitats or habitat use in the Delaware River as a result of climate change. We are not aware of other publications that indicate that any DPS of Atlantic sturgeon is shifting habitats or habitat use in response to the effects of climate change.

The commenter did not include any riverine-specific information regarding the areal influence of changes to salinity, temperature and DO, or sea level rise. We are designating as critical habitat the river areas that capture the varying distribution of the PBFs and that are appropriate to encompass the habitat essential for the conservation of the species. The designation includes all habitat required for reproduction and recruitment essential for the recovery of the DPSs, and reflects consideration of in-river changes that may result from climate change (
e.g.,
temperature, salt-water intrusion, etc.). We did consider the presence of the PBFs in each river, and the variability in the salt wedge seasonally and annually that influences where the Atlantic sturgeon life stages occur in the estuary, and we accommodated for these shifts in the critical habitat designation.

We considered whether any designations of unoccupied habitat were essential for the conservation of the Gulf of Maine, New York Bight or Chesapeake Bay DPSs because of the function they are likely to serve as climate changes, and we determined there were no such areas. We will continue to review Atlantic sturgeon habitat needs as new information about potential effects from climate change becomes available. Consistent with NMFS guidance in the context of individual section 7 consultations, we will consider how climate change interacts with a proposed action's effects on the PBFs in assessing an action's impacts on the critical habitat's

ability to support the species' recovery. These analyses will necessarily be case-by-case and dependent on the action, environmental conditions at the time in the affected river (including projected changes from climate change, if relevant), and the status of the species.

Comment 18:
An industry trade group indicated we failed to map potential threats to Atlantic sturgeon (
e.g.,
manmade structures, dredging areas). This industry trade group also noted that we did not include an exception from critical habitat for manmade structures in the regulatory language for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs.

Our Response:
Threats to the species were identified in both the Listing Rules (77 FR 5880; February 6, 2012 and 77 FR 5914; February 6, 2012) and the Status Review (ASSRT, 2007). There is no requirement to map the existence of threats to the species in a critical habitat designation. Information on activities that may affect critical habitat is properly characterized in the impact analyses. We appreciate the comment noting that we did not include an exception from critical habitat for manmade structures that do not provide the PBFs for northeastern DPSs. This was an oversight, as we did include the exception for the Carolina and South Atlantic DPSs. We have now included and clarified this exception for all five DPSs.

Comments on Designation of Unoccupied Critical Habitat

Comment 19:
A commenter asked that the final rules expand on the documentation for upstream and downstream critical habitat boundaries of the critical habitat units and identify unoccupied habitat essential to the conservation of a particular DPS. The commenter noted that many of the upstream critical habitat boundaries are defined by dams or locks, and that presence of a barrier, in and of itself, should not constitute the upstream extent of critical habitat. As one of the objectives of the rule is to “increase the abundance of each DPS by facilitating increased successful reproduction and recruitment to the marine environment,” the commenter suggested revisiting consideration of these reaches as essential, but currently unoccupied habitat.

Our Response:
Section 3(5)(A) of the ESA allows for consideration and inclusion of unoccupied habitat in a critical habitat designation if such habitat is essential for conservation of the species. The 1998 and 2007 status reviews for Atlantic sturgeon, ASMFC's 2009 review of Atlantic coast diadromous fish habitat, and the 2012 listing rule for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs (77 FR 5880; February 6, 2012) of Atlantic sturgeon reviewed historical and current use of rivers within the range of each DPS. We have considered the life history, status, and conservation needs information in these reviews, the cited literature, and new literature for each DPS (
e.g.,
Wippelhauser and Squiers, 2015 for the Gulf of Maine DPS; Breece
et al.,
2013 for the New York Bight DPS; Hager
et al.,
2014 for the Chesapeake Bay DPS). We have concluded that unoccupied habitat is not essential to the recovery of the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs because Atlantic sturgeon reproduction and rearing habitat for each DPS is available downriver of dams or in rivers that are not dammed, and the boundaries of the critical habitat areas take into consideration the seasonal and annual variations in the location of the salt wedge that influences where Atlantic sturgeon life stages occur within the estuary as well as any potential shifts that may occur as a result of climate change. Therefore, we are not designating unoccupied habitat for these DPSs.

We agree that presence of a barrier does not necessarily constitute the upstream extent of critical habitat; however, in the case of the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs of Atlantic sturgeon, the barriers included to denote the upstream limit of the designation are the same designators as the upstream limit of the area occupied and therefore are appropriate in this case. We recognize that the upstream limits of the area occupied at the time of listing is not necessarily the historical upstream limit (
e.g.,
there is historical reference to the presence of sturgeon below Mohawk Falls which is upstream of the modern-day upstream limit of Atlantic sturgeon in the Hudson River); however, we have determined that currently unoccupied habitat is not essential for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs. Additionally, barriers that occur at a critical habitat boundary provide an easily recognizable landmark for where critical habitat begins or ends. Non-ephemeral reference points (
e.g.,
dams, bridges) can be used in a textual description of the boundaries of critical habitat.

Comments Designating Specific River Units or River Areas

Comment 20:
Several environmental organizations stated that we incorrectly claimed that we could not designate estuarine or marine areas as critical habitat due to insufficient data and that the best available scientific information supports identification of PBFs in estuarine and marine environments that are essential to Atlantic sturgeon conservation. These commenters said that a growing body of research has identified critical feeding and seasonal aggregation sites, and that the sites identified to date should be designated as critical habitat. The commenters stated there is a scientific consensus that Atlantic sturgeon use marine waters of particular depths as migration corridors; the commenters asserted that available information supports the contention that all five DPSs use the same narrow migration corridor and known aggregation sites. The commenters stated that water depth, available prey, substrates, temperature, salinity and seascapes are factors correlated with, and that influence, Atlantic sturgeon use of specific estuarine and marine habitats as feeding or seasonal (winter, summer) aggregations, and migratory corridors, and that these features may require special management considerations or protection. The commenters stated that our regulations, Implementing Changes to the Regulations for Designating Critical Habitat, (81 FR 7414; February 11, 2016) support the use of generally-defined PBFs or an ecosystem approach. Finally, the commenters discussed our previous critical habitat designations for green and Gulf sturgeon as valid models for designating estuarine and marine areas as critical habitat for Atlantic sturgeon.

Our Response:
We reconsidered the information available, but reached the same conclusion that we cannot identify critical habitat for adults or subadults of any of the five Atlantic sturgeon DPSs in marine or nearshore estuarine waters at this time. We agree that the regulatory definition of PBFs is intentionally broad because we cannot predict what species will be listed in the future, and what features that support the life history needs of those species will be necessary for designating their critical habitats. However, as described in the response to comments for our regulations, Implementing Changes to the Regulations for Designating Critical Habitat (81 FR 7414; February 11, 2016), “we need to clearly articulate in our proposed and final rules designating critical habitat for each species how the essential features relate to the life-history and conservation needs of the species. This type of specificity will be in the individual proposed and final rules designating critical habitat for

each species.” Thus, while prior designations for other species may provide important background, critical habitat designations are specific to particular species, their life history traits, habitat and resource uses, and information available for that species.

Some of the literature available for Atlantic sturgeon uses the term “critical habitat” in reference to areas where Atlantic sturgeon occur. However, the literature is not applying the term “critical habitat” as it is defined in the ESA. Similarly, the word “essential” has been used in the literature, but it is not used in the same context as it is in the critical habitat regulations. The Background of our regulations (81 FR 7414; February 11, 2016) explains that “[t]he purpose of critical habitat is to identify the areas that are essential to the species' recovery.” The explanation makes clear that critical habitat is the specific area(s) essential to species recovery.

We reviewed the critical habitat designations for the Southern DPS of green sturgeon and for Gulf sturgeon in the event there were similarities in the life history of sturgeon species that could inform the essential PBFs for the Atlantic sturgeon DPSs. Marine waters were designated for Gulf sturgeon and the Southern DPS of green sturgeon based on information that certain marine waters were a migratory/connectivity corridor for subadult and adult sturgeon between estuaries and marine foraging areas. However, unlike the Southern DPS of green sturgeon and Gulf sturgeon, the available information for Atlantic sturgeon foraging in marine waters (Johnson
et al.,
1997; Dunton, 2014) is inconclusive regarding whether any particular marine waters are essential foraging areas for Atlantic sturgeon, and thus there are no identifiable migratory corridors between specific foraging areas. Furthermore, those sources do not provide the necessary information to allow us to identify what the PBFs associated with potential marine foraging for Atlantic sturgeon might be.

The scientific information available on Atlantic sturgeon forage items does not provide the specificity we need in identifying PBFs that are essential to the DPSs. The available information indicates that Atlantic sturgeon are opportunistic, benthic-cruisers that consume benthic prey over soft (unconsolidated) substrates. Other than being benthic prey, the specific Atlantic sturgeon prey items identified in the literature were common and vary between sites. Therefore, it is not possible to determine if gravel-sand and sand substrate types are essential habitat features for Atlantic sturgeon prey or, because Atlantic sturgeon are opportunistic foragers, the sturgeon happen to be feeding over these substrate types because they are ubiquitous, and we lack information to define prey, substrates or feeding areas more specifically for Atlantic sturgeon.

We cited in the preamble of the proposed rules the literature that identifies Atlantic sturgeon aggregation areas. The term “aggregation” as it is used in the literature for Atlantic sturgeon is not defined by any particular quantitative measure. The number of areas described in the literature as an “Atlantic sturgeon aggregation area” demonstrates the ubiquitous nature of Atlantic sturgeon in the marine range as well as the liberal use of the term for characterizing the presence of Atlantic sturgeon in an area. For example, the commenters referred to literature identifying Atlantic sturgeon feeding areas in the Bay of Fundy and Long Island Sound. Our background information cited to literature describing other Atlantic sturgeon foraging areas, including areas with mud bottom, gravelly-sand substrate, and sand substrate. Stein
et al.
(2004) noted that sturgeon were most often incidentally captured over gravelly-sand and sand substrate and suggested that their presence was associated with foraging. However, Stein
et al.
(2004) also reflected that the gravel-sand and sand substrate types were the dominant substrate types along the coastline, so it was uncertain if Atlantic sturgeon presence was correlated to the substrate type or if Atlantic sturgeon presence was coincidental to the substrate type.

The commenters referred to Laney
et al.
(2007) as demonstrating that “shallow, nearshore waters off North Carolina are an important winter habitat for Atlantic sturgeon.” The commenters did not provide information for why these particular shallow, nearshore waters are essential to one or more of the Atlantic sturgeon DPSs compared to all shallow, nearshore waters that are accessible to the DPSs. We need to have information to be able to make the connection between species' presence and presence of one or more PBFs that are essential to the conservation of the species and may require special management or protection. The commenters did not provide, and we could not find, information to distinguish these shallow, nearshore waters from other shallow, nearshore waters, or information that identifies more specific features of these waters. Tagging work by Erickson
et al.
(2011) showed that adult Atlantic sturgeon from the Hudson River move about within the Mid-Atlantic Bight, occurring as far south as Delaware for the late fall to early winter and then as far south as the area off Chesapeake Bay for the latter part of the winter. The data do not suggest movement from the river to a specific overwintering area where the fish reside throughout the winter. The available information for where Atlantic sturgeon occur in the winter also includes evidence of sturgeon in marine waters off estuaries where they were detected in the fall, sturgeon making long migrations along the coast to southern coastal waters, sturgeon possibly overwintering in an estuary, and at least one sturgeon moving in and out of a Gulf of Maine estuary during the winter (Laney
et al.,
2007; Dunton
et al.,
2010; Oliver
et al.,
2013; Dunton
et al.
2015; Taylor
et al.
2016; C. Hager, Chesapeake Scientific, pers. comm.; T. Savoy, CT DEEP, pers. comm.; G. Zydlewski, Univ. of Maine, pers. comm.). Because this information is conflicting, we could not determine whether or where overwintering areas are essential to one or more of the Atlantic sturgeon DPSs.

We cannot designate critical habitat based on the presence of the species alone. Therefore, while we acknowledge there is literature that identifies aggregation areas where Atlantic sturgeon are generally found, it does not provide specificity as to the purpose of the aggregations or the features that support those purposes. Therefore, we do not believe it provides the information we need to meet the statutory and regulatory requirements to designate critical habitat.

The commenters stated that the Atlantic sturgeon DPSs use a narrow migratory corridor within marine waters and we should designate this narrow corridor as critical habitat. The commenters' characterization of these waters as a “narrow corridor” is subjective. As we described in the preamble for the proposed rules, Atlantic sturgeon generally occur within the 50 m depth contour. However, the literature is not consistent for the depth contour where Atlantic sturgeon occur in the marine environment. Based on fisheries-dependent data for incidental captures of Atlantic sturgeon, Stein
et al.
(2004) described that “peak sturgeon captures along the coast were approximately bracketed by isobaths ranging from 10 to 50 m” while Dunton
et al.,
(2010), using both fisheries-dependent and fisheries-independent data of incidental Atlantic sturgeon captures, concluded that “Atlantic

sturgeon were largely confined to water depths less than 20 meters.” Erickson
et al.
(2011), using location data of tagged Atlantic sturgeon, described the mean range of marine waters where Atlantic sturgeon occurred as 9.9 to 24.4 m depth depending on time of year. Erickson
et al.
also noted differences between fish, with some sturgeon using more shallow waters (5-15 m) and some using deeper waters (35-70 m) compared to the other tagged Atlantic sturgeon. Given these inconsistencies, we could not identify the PBFs that facilitate migration for any of the five DPSs.

The commenters also pointed to the findings of Breece
et al.
(2016) as research that could inform our designation of critical habitat in marine waters, nearshore bays, and sounds. Noting that Atlantic sturgeons' seasonal coastal migrations are difficult to predict, Breece
et al.
(2016) used ocean color and sea surface temperature recorded during the spring to partition waters of the Delaware Bay and ocean waters off Delaware Bay into six “seascapes,” and tested the hypothesis that these seascapes are predictors of the occurrence of Atlantic sturgeon during their spring migration in the mid-Atlantic. The commenters stated that Seascape E is a physical feature of marine waters that is essential to the Atlantic sturgeon DPSs (
e.g.,
for migrating between estuaries and marine waters and for where Atlantic sturgeon spend most of their life in marine waters) and asked us to designate marine waters as critical habitat for the Atlantic sturgeon DPSs. We considered and cited the Breece
et al.
(2016) study for the information that it provides for Atlantic sturgeon marine distribution. However, we did not conclude that Seascape E was an essential PBF because: (1) The equipment to detect sturgeon was primarily placed in or occurred within Seascape E, and the information was not provided on the presence of Seascape E in other parts of the marine range; and (2) because a clear correlation between what specific PBF(s) is essential to the conservation of the species could not be determined.

The Breece
et al.
(2016) study was temporally and geographically limited in scope relative to the range of the DPSs. Detection data were collected by fixed receivers and by receivers fixed to a glider for the months of April through June, the period of peak Atlantic sturgeon abundance during spring migration (Breece
et al.,
2016). More than half of the fixed receivers were located in Delaware Bay. The remaining receivers were placed within approximately 20 km of the shoreline along the coast from approximately 30 km (
i.e.,
off New Jersey) and south (
i.e.,
off Maryland) of the mouth of the Bay. The glider mission covered a greater area; within approximately 25 km of the shoreline along a 120 km stretch of coastline between Bethany Beach, Delaware (south of the mouth of the Bay), and Chincoteague, Virginia. While the geographic area covered is large and the time period is when we would expect many Atlantic sturgeon to occur in the areas, this is a small geographic area, relatively mid-range, of the expansive Atlantic sturgeon DPSs' marine range from Canada to Florida, United States. Breece
et al.
(2016) noted that the variables used to define the seascapes were so dynamic, that the results of the study were presented with respect to an 8-day average of ocean color and sea surface temperature for each seascape. Based on the average, Seascape E was the most prevalent seascape class in the study area, and the equipment to detect the presence of Atlantic sturgeon occurred primarily within Seascape E. Additionally, Breece
et al.
(2016) were unable to determine why Atlantic sturgeon were associated with Seascape E. The authors state: “[f]ull understanding of the processes driving the association of Atlantic Sturgeon to Seascape E is not yet known; however, it appears we can use this global product to estimate spatial occurrence without requiring direct observation of individuals to inform coastal ocean users during spring migration.” Therefore, while potentially useful to resource managers for identifying potential areas of high sturgeon abundance in the Mid-Atlantic Bight region, the information still does not help us understand what, if any, PBFs exist in the area that may be essential to the conservation of the species.

Finally, the commenters stated that Atlantic sturgeon aggregation areas in marine and nearshore estuarine waters should be designated as critical habitat because these require special management and protection as a result of vessel strikes of Atlantic sturgeon from ships using the marine corridors, strikes from turbine blades in tidal estuaries, impingement and entrainment in water intakes, fisheries bycatch, and other threats to the fish including dredging, sand mining, pipeline and other construction, wind farm development, and impaired water quality. However, special management considerations or protection in the context of critical habitat designations are the methods or procedures useful in protecting the PBFs essential to the conservation of the listed species. The threats described by the commenters are threats to individual Atlantic sturgeon and not their habitat.

Comment 21:
Several additional environmental organizations, including one that established an online form letter submission from which we received over 1,000 form letters, as well as a representative for New York State Department of Environmental Conservation, and academics, also pointed to the publications by Dunton
et al.
(2015) and Breece
et al.
(2016) and stated that we should designate critical habitat for the Atlantic sturgeon DPSs in marine waters, bays, and sounds.

Our Response:
Some bays are part of the critical habitat designations. These include Merrymeeting Bay of the Kennebec River critical habitat unit, and Haverstraw Bay of the Hudson River critical habitat unit. Bays that occur between the mouth of the river and the Atlantic Ocean, such as Chesapeake Bay, are not part of the designated critical habitat because we do not have information that these areas contain PBFs that are essential to reproduction and recruitment of the offspring. The available information describes spawning adults as moving into the rivers and either staging in the river for a period of time or immediately moving upriver to spawning areas and, similarly, after spawning, moving downriver and either remaining in the river until outmigration in the fall or leaving immediately to move to other estuarine systems (Savoy and Pacileo, 2003; ASSRT, 2007; Greene
et al.,
2009; Simpson, 2008; Austin, 2012; Balazik
et al.,
2012; Breece
et al.,
2013; Hager
et al.,
2014; Kahn
et al.,
2014). Juveniles spend months to years in the natal estuary, moving upriver and downriver with seasonal and annual changes in the salt front to access rearing habitat (
e.g.,
within their preferred salinity range). There is no information that natal juveniles are moving as far downriver as a bay or sound between the river mouth and the ocean, and returning to the natal river without continuing the outmigration to the ocean. Available information from tracking suggests they move downriver through the river estuary, into and through any adjoining bay or sound upon their first outmigration to the ocean. Thus, while soft substrate between the river mouth and spawning sites is essential for successful recruitment, we do not have information that soft substrate in these bays and sounds is essential to recruitment of the offspring to the marine environment. The comments did not provide new information for juvenile use of bays and sounds between the natal river and the ocean.

See also our response to Comment 20, and the biological information for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs in the Impacts Analysis and Biological Information Source Document.

Comment 22:
A commenter stated that further spatial delineation of the Delaware River critical habitat areas is essential, given the multiple and vital uses of this waterway, which include but are not limited to: 94 discharges regulated under a Total Maximum Daily Load for polychlorinated biphenyls (PCBs) under the Clean Water Act; multiple water withdrawals serving regional populations; and significant commercial navigation. In addition, given the varying requirements of the different life stages of the Atlantic sturgeon, temporal delineation of critical habitat should also be considered for the final designation.

Our Response:
The PBFs that support reproduction and recruitment and that are essential to the conservation of the New York Bight DPS are all of those that we have identified in the proposed critical habitat designation. These may require special management considerations or protection as a result of certain kinds of activities, including activities listed by the commenter. We are, therefore, required to designate these areas as critical habitat for the New York Bight DPS. The boundaries of each critical habitat area, including the Delaware River critical habitat area, encompass no more and no less than the area containing the PBFs essential to the conservation of the DPS and which may require special management considerations or protection.

It appears that the commenter is requesting that we identify the specific areas within the Delaware River where each of the features occurs; however, this goes beyond the scope of what is required in a critical habitat designation. (see
Home Builders Ass'n of Northern California
v.
U.S. Fish and Wildlife Service,
616 F.3d 983 (9th Cir., 2010)). We have provided references in the rule, and in the Impacts Analysis and Biological Information Source Document that support our determination that the PBFs are present in the area designated and can provide guidance to Federal agencies when they need to request ESA section 7 consultation and consider the effects of their actions on critical habitat.

We do not use temporal designations for critical habitat because the PBFs are either present year round or will be present at some expected time during the year that cannot be predicted with precision (
e.g.,
the location of the salt front moves throughout the year, but given the multitude of factors that influence the exact location, we could not predict with any reasonable certainty the timing of any particular location). The timing of a proposed Federal action and the effects it would have on the critical habitat are considered during ESA section 7 consultation. For example, the effects of an activity that will impact hard substrate in freshwater reaches of the Delaware River may be different during the spawning season than during the winter.

Comment 23:
The Navy raised concern that freshwater suitable for Atlantic sturgeon spawning was not available to Atlantic sturgeon in the Piscataqua River system below the lowermost dams of the Salmon Falls and Cocheco Rivers.

Our Response:
Freshwater is available below the lowermost dams of the Salmon Falls and Cocheco Rivers. The salinity changes within the river estuary seasonally and daily depending on freshwater flow and tidal changes. See our response to Comment 3 for additional information on the Piscataqua River.

Comment 24:
A commenter stated that nearshore shallow water areas of the Potomac River from Key Bridge to at least Marshall Hall should not be considered critical habitat because substrate from at least Marshall Hall to Key Bridge is deeply silty, and near shore salinity is closer to fresh than to 0.5 ppt salinity. The commenter stated that the feature is substrate with salinity greater than 0.5 ppt. Therefore, this area should not be designated critical habitat.

Our Response:
We are not required to determine that every segment of the critical habitat contains all of the PBFs essential to conservation of the species, but rather, we demonstrate overall that the designated unit contains the PBFs essential to conservation of the species. We have provided references in the rule, and in the Impacts Analysis and Biological Information Source Document that support our determination that the PBFs are present in the area designated as critical habitat in the Potomac River. Briefly, the Potomac River estuary extends approximately 187 river kilometers (rkm) from the Chain Bridge to the mouth of the river. The river is tidal freshwater from Chain Bridge to Quantico, VA; the mixing zone of transitional salinity occurs from Quantico, VA, to the crossing of the U.S. Highway 301 Bridge, MD, and the remainder of the river estuary, from the U.S. Highway 301 Bridge crossing to the Chesapeake Bay, has a wide channel with gradually sloping, shallow flats near shore (USGS, 1984).

Comment 25:
The Virginia Institute of Marine Science provided new information, based on their data collections, that adult Atlantic sturgeon occur upriver of the Route 360 bridges on both the Pamunkey and Mattaponi Rivers.

In 2015, a receiver placed at rkm 144 of the Pamunkey River, 5 km above the Route 360 Bridge, regularly detected 18 acoustically-tagged, adult sturgeon during the summer and early fall. The commenter believes that the occurrence of the adults in freshwater of the Pamunkey River during the spawning period (Hager
et al.,
2014; Kahn
et al.,
2014) and the detected movements of the adults support that the geographical area occupied includes the waters at least 5 km upriver of the Route 360 Bridge crossing, and suggests that this part of the Pamunkey River has the essential PBFs of critical habitat based on patches of sand from bank erosion. The commenter recommends that we extend critical habitat above the Route 360 bridge in the Pamunkey River approximately 14 rkm up to Nelson's Bridge Road Route 615 crossing on the Pamunkey.

The commenter also recommended extending the upriver boundary of the Mattaponi critical habitat unit by 10 rkm above the Route 360 bridge to rkm 122. In the summer and early fall of 2015, one tagged adult female Atlantic sturgeon ascended the Mattaponi River and was detected at the uppermost receiver located near the Route 360 bridge crossing. This is during the time and in an area where spawning would be expected to occur. Based on the time series of detections at this receiver, the commenter believes this individual moved past the receiver upstream, then moved back down again.

Our Response:
We considered the information provided and agree that the detected presence of at least 18 adult Atlantic sturgeon in the Pamunkey River above the Route 360 Bridge crossing provides evidence that the geographical area occupied by the DPS in the Pamunkey is above the Bridge crossing, and the area is used by adults during the fall spawning period for the Chesapeake Bay DPS. We did not agree with the commenter that sand from bank erosion is evidence that hard substrate occurs in the area. However, the literature cited in the comments (
e.g.,
Bushnoe
et al.,
2005) provides additional information for hard substrate (gravel) in the area. We, therefore, revised the boundary of the York River critical habitat unit by extending critical habitat by

approximately 14 rkm to the Nelson's Bridge Road Route 615 crossing on the Pamunkey River.

We did not revise the upriver boundary of the critical habitat designation on the Mattaponi River. We have considered the information provided by VIMS. While their data analysis suggests to them that the fish moved further upriver, there is no evidence that it moved upriver and, even if it did, these are the movements of just one fish. We cannot determine whether the movements of this fish are representative of all Atlantic sturgeon that occur in the Mattaponi or are movements of a vagrant fish. Additionally, critical habitat is based on the presence of the essential PBFs. VIMS did not provide information that the PBFs of critical habitat occur in the Mattaponi River upriver of the Route 360 Bridge crossing. Therefore, we are not changing the upriver boundary for the York River critical habitat unit in the Mattaponi River.

Comment 26:
Maryland Department of Natural Resources (MD DNR) requested amendment of the critical habitat designation for the Chesapeake DPS to include: Marshyhope Creek; Broad Creek; Deep Creek; and, areas of the Nanticoke River above its confluence with the Marshyhope Creek and the lower Nanticoke River down to Chapter Point, MD. The MD DNR provided the 2016 project report for riverbed mapping of the Broad Creek, Marshyhope Creek, and Nanticoke River (Bruce
et al.,
2016), information on the detection of an adult Atlantic sturgeon in spawning condition, and salinity, water temperature, and DO in Marshyhope Creek, Broad Creek, and the Nanticoke River.

Our Response:
The substrate information for Marshyhope Creek and the Nanticoke River was not received in time for us to consider it for inclusion in the proposed rule. However, we were aware that a final report was imminent and alerted the public in the Impacts Analysis and Biological Information Source Document to the proposed rule that the presence of adult sturgeon in spawning condition and at the time when the Chesapeake Bay DPS spawns suggests that the PBFs essential to Atlantic sturgeon reproduction and recruitment are present in Marshyhope Creek. We also alerted the public that after receiving the report, we would assess whether to expand critical habitat to include this area. The final project report was submitted to us by the MD DNR during the public comment period. We reviewed the information as well as other available information for the Nanticoke River, including the MD DNR final report, “Assessment of Critical Habitats for Recovering the Chesapeake Bay Atlantic Sturgeon Distinct Population Segment,” funded by the NOAA Species Recovery Grants to States (ESA Section 6 Program). The benthic mapping report does provide information to confirm the presence of hard substrate in low salinity waters of Marshyhope Creek and the Nanticoke River. In addition, the MD DNR Section 6 report provides evidence that the area is likely being used for spawning. This information along with information related to the presence of suitable spawning substrate (Bruce
et al.,
2016) indicates that there is the potential for spawning and recruitment to occur in the Nanticoke River and Marshyhope Creek.

Our review of this best available information confirmed that critical habitat for the Chesapeake Bay DPS occurs in the Nanticoke River and its tributary, Marshyhope Creek. Designation of the area is a natural outgrowth of the proposed rule given that we stated in the proposed rule that we suspected spawning was occurring in Marshyhope Creek, a tributary of the Nanticoke, and we stated in the Impacts Analysis and Biological Information Source Document that we were awaiting receipt of substrate information and would consider designating critical habitat in the River if we received additional information that confirmed that the PBFs are present. The PBFs may require special management considerations or protection as a result of activities, such as dredging and construction projects (
e.g.,
docks, piers), that may affect the PBFs. Therefore, we are designating critical habitat in the Nanticoke River and Marshyhope Creek for the Chesapeake Bay DPS.

We are not, however, designating critical habitat in the Nanticoke River and Marshyhope Creek as two separate areas as recommended by MD DNR, and we are not designating critical habitat in Broad Creek or Deep Creek. Critical habitat that is designated within the geographical area occupied by the species is based on the presence of the PBFs. While information on salinity and water quality is generally available, information on hard substrate (
e.g.,
gravel, cobble) in low salinity waters is not available for Broad Creek or Deep Creek. The substrate study did indicate the presence of gravel-sand, and sand-gravel in Broad Creek, but hard substrate such as gravel and cobble that provides interstitial spaces for the offspring after hatching is essential for spawning. We will reconsider Broad Creek and Deep Creek as new information becomes available on hard substrate and information to show that these areas could be used by Atlantic sturgeon for spawning (
e.g.,
evidence of spawning adult presence in the area, evidence for the presence of natal offspring).

Based on the PBFs essential to the conservation of the Chesapeake Bay DPS, the Nanticoke River system critical habitat unit consists of the waters of the Nanticoke River from the Maryland State Route 313 Bridge crossing near Sharptown, MD, to where the main stem discharges at its mouth into the Chesapeake Bay as well as Marshyhope Creek from its confluence with the Nanticoke River and upriver to the Maryland State Route 318 Bridge crossing near Federalsburg, MD, for a total of 60 rkm of aquatic habitat.

Comment 27:
One commenter requested consideration of additional literature and datasets for determining whether to include the Eastern River, Abagadasset River, Muddy River, Sheepscot River up to Head Tide Dam, Dyer River up to Boynton Trask Dam, Saco River from Cataract Dam downstream to its mouth, Mousam River below the confluence with Fernald Brook, tributaries of Great Bay (Spruce Creek, Berrys Brook, Sagamore Creek, Lubberland Creek, Crommet Creek, Bellamy River, Sturgeon Creek), and Penobscot Bay as critical habitat for the Gulf of Maine DPS. The commenter also indicated that the Taunton River, MA, up to the confluence with the Nemasket River should be included in the critical habitat designation for the New York Bight DPS.

Our Response:
We have reviewed the additional information and datasets referenced by the commenter. We are not adding these additional areas to the critical habitat designations. We discussed in our response to Comment 20 why the critical habitat designations for the Gulf of Maine, New York Bight, and Chesapeake Bay DPSs do not include bays and sounds that occur between the river mouth and the ocean, such as Penobscot Bay. No information was provided by the commenter that allowed us to identify PBFs in Penobscot Bay.

As described in our regulations at 50 CFR 424.12(b)(1) and the proposed rule, critical habitat must contain the PBFs essential to the conservation of the DPS, and that may require special management or protection. The Cataract Dam is located downriver of freshwater, and Atlantic sturgeon do not pass upri

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2017-17207. Public record. Not legal advice.