# 81 FR 96304: Endangered and Threatened Wildlife and Plants; Proposed Threatened Listing Determination for the Oceanic Whitetip Shark Under the Endangered Species Act (ESA)

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URL: https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2016-31460

## Section

- **Citation:** 81 FR 96304
- **Heading:** Endangered and Threatened Wildlife and Plants; Proposed Threatened Listing Determination for the Oceanic Whitetip Shark Under the Endangered Species Act (ESA)
- **Jurisdiction:** Federal
- **Kind:** Regulations
- **Status:** In force
- **Text as of:** August 14, 2026
- **Source:** Compiled text
- **Location:** Federal Register / Vol. 81 / 81 FR 96304

## Text

DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration 50 CFR Part 223 [Docket No. 151110999-6999-02] RIN 0648-XE314 Endangered and Threatened Wildlife and Plants; Proposed Threatened Listing Determination for the Oceanic Whitetip Shark Under the Endangered Species Act (ESA) AGENCY:
National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.

ACTION:
Proposed rule; request for comments.

SUMMARY:
NMFS has completed a comprehensive status review under the Endangered Species Act (ESA) for the oceanic whitetip shark ( Carcharhinus longimanus ) in response to a petition from Defenders of Wildlife to list the species. Based on the best scientific and commercial information available, including the status review report (Young et al., 2016), and after taking into account efforts being made to protect the species, we have determined that the oceanic whitetip shark warrants listing as a threatened species. We conclude that the oceanic whitetip shark is likely to become endangered throughout all or a significant portion of its range within the foreseeable future. Any protective regulations determined to be necessary and advisable for the conservation of the species under ESA section 4(d) would be proposed in a subsequent Federal Register announcement. Should the proposed listing be finalized, we would also designate critical habitat for the species, to the maximum extent prudent and determinable. We solicit information to assist in this listing determination, the development of proposed protective regulations, and the designation of critical habitat in the event this proposed listing determination is finalized.

DATES:
Comments on this proposed rule must be received by March 29, 2017. Public hearing requests must be requested by February 13, 2017
ximum extent prudent and determinable. We solicit information to assist in this listing determination, the development of proposed protective regulations, and the designation of critical habitat in the event this proposed listing determination is finalized.

DATES:
Comments on this proposed rule must be received by March 29, 2017. Public hearing requests must be requested by February 13, 2017.

ADDRESSES:
You may submit comments on this document, identified by NOAA-NMFS-2015-0152, by either of the following methods:
• Electronic Submissions: Submit all electronic comments via the Federal eRulemaking Portal. Go to www.regulations.gov/#!docketDetail;D=NOAA-NMFS-2015-0152, click the “Comment Now!” icon, complete the required fields, and enter or attach your comments.
• Mail: Submit written comments to Chelsey Young, NMFS Office of Protected Resources (F/PR3), 1315 East West Highway, Silver Spring, MD 20910, USA. Attention: Oceanic whitetip proposed rule.
Instructions: Comments sent by any other method, to any other address or individual, or received after the end of the comment period, may not be considered by NMFS. All comments received are a part of the public record and will generally be posted for public viewing on www.regulations.gov without change. All personal identifying information ( e.g., name, address, etc.), confidential business information, or otherwise sensitive information submitted voluntarily by the sender will be publicly accessible. NMFS will accept anonymous comments (enter “N/A” in the required fields if you wish to remain anonymous).
You can find the petition, status review report, Federal Register notices, and the list of references electronically on our Web site at http://www.nmfs.noaa.gov/pr/species/fish/oceanic-whitetip-shark.html. You may also receive a copy by submitting a request to the Office of Protected Resources, NMFS, 1315 East-West Highway, Silver Spring, MD 20910, Attention: Oceanic whitetip proposed rule
ous).
You can find the petition, status review report, Federal Register notices, and the list of references electronically on our Web site at http://www.nmfs.noaa.gov/pr/species/fish/oceanic-whitetip-shark.html. You may also receive a copy by submitting a request to the Office of Protected Resources, NMFS, 1315 East-West Highway, Silver Spring, MD 20910, Attention: Oceanic whitetip proposed rule.
FOR FURTHER INFORMATION CONTACT:
Chelsey Young, NMFS, Office of Protected Resources, (301) 427-8403.

SUPPLEMENTARY INFORMATION:

Background
On September 21, 2015, we received a petition from Defenders of Wildlife to list the oceanic whitetip shark ( Carcharhinus longimanus ) as threatened or endangered under the ESA throughout its entire range, or, as an alternative, to list two distinct population segments (DPSs) of the oceanic whitetip shark, as described in the petition, as threatened or endangered, and to designate critical habitat. We found that the petitioned action may be warranted for the species; on January 12, 2016, we published a positive 90-day finding for the oceanic whitetip shark (81 FR 1376), announcing that the petition presented substantial scientific or commercial information indicating the petitioned action of listing the species may be warranted range wide, and explaining the basis for those findings. We also announced the initiation of a status review of the species, as required by section 4(b)(3)(a) of the ESA, and requested information to inform the agency's decision on whether the species warranted listing as endangered or threatened under the ESA.
Listing Species Under the Endangered Species Act
We are responsible for determining whether species are threatened or endangered under the ESA (16 U.S.C. 1531 et seq. ). To make this determination, we first consider whether a group of organisms constitutes a “species” under section 3 of the ESA, then whether the status of the species qualifies it for listing as either threatened or endangered
Listing Species Under the Endangered Species Act
We are responsible for determining whether species are threatened or endangered under the ESA (16 U.S.C. 1531 et seq. ). To make this determination, we first consider whether a group of organisms constitutes a “species” under section 3 of the ESA, then whether the status of the species qualifies it for listing as either threatened or endangered. Section 3 of the ESA defines species to include “any subspecies of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish or wildlife which interbreeds when mature.” On February 7, 1996, NMFS and the U.S. Fish and Wildlife Service (USFWS; together, the Services) adopted a policy describing what constitutes a DPS of a taxonomic species (61 FR 4722). The joint DPS policy identified two elements that must be considered when identifying a DPS: (1) The discreteness of the population segment in relation to the remainder of the species (or subspecies) to which it belongs; and (2) the significance of the population segment to the remainder of the species (or subspecies) to which it belongs.
Section 3 of the ESA defines an endangered species as “any species which is in danger of extinction throughout all or a significant portion of its range” and a threatened species as one “which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.” Thus, in the context of the ESA, the Services interpret an “endangered species” to be one that is presently at risk of extinction. A “threatened species,” on the other hand, is not currently at risk of extinction, but is likely to become so in the foreseeable future. In other words, a key statutory difference between a threatened and endangered species is the timing of when a species may be in danger of extinction, either now (endangered) or in the foreseeable future (threatened)
e one that is presently at risk of extinction. A “threatened species,” on the other hand, is not currently at risk of extinction, but is likely to become so in the foreseeable future. In other words, a key statutory difference between a threatened and endangered species is the timing of when a species may be in danger of extinction, either now (endangered) or in the foreseeable future (threatened). The statute also requires us to determine whether any species is endangered or threatened as a result of any of the following five factors: The present or threatened destruction, modification, or curtailment of its habitat or range; overutilization for commercial, recreational, scientific, or educational purposes; disease or Policy on Evaluation of Conservation Efforts When Making Listing Decisions (“PECE”; 68 FR 15100; March 28, 2003) for any conservation efforts that have not been implemented, or have been implemented but have not yet demonstrated effectiveness.
Status Review
We convened a team of agency scientists to conduct the status review for the oceanic whitetip shark and prepare a report. The status review report of the oceanic whitetip shark (Young et al., 2016) compiles the best available information on the status of the species as required by the ESA and assesses the current and future extinction risk for the species, focusing primarily on threats related to the five statutory factors set forth above. We appointed a biologist in the Office of Protected Resources Endangered Species Conservation Division to undertake a scientific review of the life history and ecology, distribution, abundance, and threats to the oceanic whitetip shark. Next, we convened a team of biologists and shark experts (hereinafter referred to as the Extinction Risk Analysis (ERA) team) to conduct an extinction risk analysis for the species, using the information in the scientific review
angered Species Conservation Division to undertake a scientific review of the life history and ecology, distribution, abundance, and threats to the oceanic whitetip shark. Next, we convened a team of biologists and shark experts (hereinafter referred to as the Extinction Risk Analysis (ERA) team) to conduct an extinction risk analysis for the species, using the information in the scientific review. The ERA team was comprised of a natural resource management specialist from NMFS Office of Protected Resources, a fishery management specialist from NMFS' Highly Migratory Species (HMS) Management Division, and four research fishery biologists from NMFS' Southeast, Northeast, Southwest, and Pacific Island Fisheries Science Centers. The ERA team had group expertise in shark biology and ecology, population dynamics, highly migratory species management, and stock assessment science. The status review report presents the ERA team's professional judgment of the extinction risk facing the oceanic whitetip shark but makes no recommendation as to the listing status of the species. The status review report is available electronically at http://www.nmfs.noaa.gov/pr/species/fish/oceanic-whitetip-shark.html.
The status review report was subjected to independent peer review as required by the Office of Management and Budget Final Information Quality Bulletin for Peer Review (M-05-03; December 16, 2004). The status review report was peer reviewed by five independent specialists selected from the academic and scientific community, with expertise in shark biology, conservation and management, and specific knowledge of oceanic whitetip sharks. The peer reviewers were asked to evaluate the adequacy, appropriateness, and application of data used in the status review as well as the findings made in the “Assessment of Extinction Risk” section of the report. All peer reviewer comments were addressed prior to finalizing the status review report
e in shark biology, conservation and management, and specific knowledge of oceanic whitetip sharks. The peer reviewers were asked to evaluate the adequacy, appropriateness, and application of data used in the status review as well as the findings made in the “Assessment of Extinction Risk” section of the report. All peer reviewer comments were addressed prior to finalizing the status review report.
We subsequently reviewed the status review report, its cited references, and peer review comments, and believe the status review report, upon which this proposed rule is based, provides the best available scientific and commercial information on the oceanic whitetip shark. Much of the information discussed below on oceanic whitetip shark biology, distribution, abundance, threats, and extinction risk is attributable to the status review report. However, we have independently applied the statutory provisions of the ESA, including evaluation of the factors set forth in section 4(a)(1)(A)-(E), our regulations regarding listing determinations, and our DPS policy in making the 12-month finding determination.
Life History, Biology, and Status of the Petitioned Species
Taxonomy and Species Description
The oceanic whitetip shark belongs to the family Carcharhinidae and is classified as a requiem shark (Order Carcharhiniformes). The oceanic whitetip belongs to the genus Carcharhinus, which includes other pelagic species of sharks, such as the silky shark ( Carcharhinus falciformis ) and dusky shark ( C. obscuras ), and is the only truly oceanic ( i.e., pelagic) shark of its genus (Bonfil et al., 2008). The oceanic whitetip shark has a stocky build with a large rounded first dorsal fin and very long and wide paddle-like pectoral fins. The first dorsal fin is very wide with a rounded tip, originating just in front of the rear tips of the pectoral fins. The second dorsal fin originates over or slightly in front of the base of the anal fin
c ( i.e., pelagic) shark of its genus (Bonfil et al., 2008). The oceanic whitetip shark has a stocky build with a large rounded first dorsal fin and very long and wide paddle-like pectoral fins. The first dorsal fin is very wide with a rounded tip, originating just in front of the rear tips of the pectoral fins. The second dorsal fin originates over or slightly in front of the base of the anal fin. The species also exhibits a distinct color pattern of mottled white tips on its front dorsal, caudal, and pectoral fins with black tips on its anal fin and on the ventral surfaces of its pelvic fins. The head has a short and bluntly rounded nose and small circular eyes with nictitating membranes. The upper jaw contains broad, triangular serrated teeth, while the teeth in the lower jaw are more pointed and are only serrated near the tip. The body is grayish bronze to brown in color, but varies depending upon geographic location. The underside is whitish with a yellow tinge on some individuals (Compagno 1984).
Current Distribution
The oceanic whitetip shark is distributed worldwide in epipelagic tropical and subtropical waters between 30° North latitude and 35° South latitude (Baum et al., 2006). In the western Atlantic, oceanic whitetips occur from Maine to Argentina, including the Caribbean and Gulf of Mexico. In the central and eastern Atlantic, the species occurs from Madeira, Portugal south to the Gulf of Guinea, and possibly in the Mediterranean Sea. In the western Indian Ocean, the species occurs in waters of South Africa, Madagascar, Mozambique, Mauritius, Seychelles, India, and within the Red Sea. Oceanic whitetips also occur throughout the Western and Central Pacific Ocean, including China, Taiwan, the Philippines, New Caledonia, Australia (southern Australian coast), Hawaiian Islands south to Samoa Islands, Tahiti and Tuamotu Archipelago and west to the Galapagos Islands
species occurs in waters of South Africa, Madagascar, Mozambique, Mauritius, Seychelles, India, and within the Red Sea. Oceanic whitetips also occur throughout the Western and Central Pacific Ocean, including China, Taiwan, the Philippines, New Caledonia, Australia (southern Australian coast), Hawaiian Islands south to Samoa Islands, Tahiti and Tuamotu Archipelago and west to the Galapagos Islands. Finally, in the eastern Pacific, the species occurs from southern California to Peru, including the Gulf of California and Clipperton Island (Compagno 1984).
Habitat Use and Movement
The oceanic whitetip shark is a highly migratory species of shark that is usually found offshore in the open ocean, on the outer continental shelf, or around oceanic islands in deep water, occurring from the surface to at least 152 meters (m) depth. Although the oceanic whitetip can be found in decreasing numbers out to latitudes of 30° N and 35° S, with abundance decreasing with greater proximity to continental shelves, it has a clear preference for open ocean waters between 10° S and 10° N (Backus et al., 1956; Strasburg 1958; Compagno 1984; Bonfil et al., 2008). The species can be found in waters between 15 °C and 28 °C, but it exhibits a strong preference for the surface mixed layer in water with temperatures above 20 °C, and is considered a surface-dwelling shark. It et al., 2013; Howey et al., 2016). However, exposures to these cold temperatures are not sustained (Musyl et al., 2011; Tolotti et al., 2015a) and there is some evidence to suggest the species tends to withdraw from waters below 15 °C ( e.g., the Gulf of Mexico in winter; Compagno 1984).
Little is known about the movement or possible migration paths of the oceanic whitetip shark. Although the species is considered highly migratory and capable of making long distance movements, tagging data provides evidence that this species also exhibits a high degree of philopatry ( i.e., site fidelity) in some locations
waters below 15 °C ( e.g., the Gulf of Mexico in winter; Compagno 1984).
Little is known about the movement or possible migration paths of the oceanic whitetip shark. Although the species is considered highly migratory and capable of making long distance movements, tagging data provides evidence that this species also exhibits a high degree of philopatry ( i.e., site fidelity) in some locations. To date, there have been three tagging studies conducted on oceanic whitetip sharks in the Atlantic. Mark recapture data (number tagged = 645 and recaptures = 8) from the NMFS Cooperative Shark Tagging Program between 1962 and 2015 provide supporting evidence that the range of movement of oceanic whitetip sharks is large, with potential for transatlantic movements (Kohler et al., 1998; NMFS, unpublished data). Maximum time at liberty was 3.3 years and the maximum distance traveled was 1,225 nautical miles (nmi0 (2,270 kilometers (km0). These data indicate movements from the northeastern Gulf of Mexico to the Atlantic Coast of Florida, from the Mid-Atlantic Bight to southern Cuba, from the Lesser Antilles west into the central Caribbean Sea, from east to west along the equatorial Atlantic, and from off southern Brazil in a northeasterly direction. In the Bahamas, oceanic whitetips tagged at Cat Island stayed within 500 km of the tagging site for ~30 days before dispersing across 16,422 km 2 of the western North Atlantic. Maximum individual displacement from the tagging site ranged from 290-1,940 km after times at liberty from 30-245 days, with individuals moving to several different destinations ( e.g., the northern Lesser Antilles, the northern Bahamas, and north of the Windward Passage). Many sharks returned to the Bahamas after ~150 days and estimated residency times within the Bahamas Exclusive Economic Zone (EEZ), were generally high (mean=68.2 percent of time; Howey-Jordan et al., 2013). Oceanic whitetip sharks showed similar movement patterns and site fidelity in a tagging study conducted in Brazil
ern Lesser Antilles, the northern Bahamas, and north of the Windward Passage). Many sharks returned to the Bahamas after ~150 days and estimated residency times within the Bahamas Exclusive Economic Zone (EEZ), were generally high (mean=68.2 percent of time; Howey-Jordan et al., 2013). Oceanic whitetip sharks showed similar movement patterns and site fidelity in a tagging study conducted in Brazil. Although individuals tended to travel long distances before returning to the tagging area, tagging and pop-up sites were relatively close to each other. In fact, five out of eight sharks ended their tracks relatively close to their starting points, even after traveling several thousand kilometers (Tolotti et al., 2015a).
In the Indo-Pacific, two tagging studies of oceanic whitetip shark have been conducted: one in the central Pacific and one in the western Indian Ocean. In the central Pacific, oceanic whitetip sharks showed a complex movement pattern generally restricted to tropical waters north of the North Equatorial Countercurrent near the tagging location. Maximum time at liberty was 243 days, but the largest linear movement was 2,314 nmi (4,285 km) in 95 days (Musyl et al., 2011). Similar to previously discussed studies, long distance movements were also observed in the Indian Ocean, with one tag that remained attached for 100 days. This individual displayed extensive horizontal movement covering a distance of approximately 6,500 km during the monitored period, moving from the Mozambique Channel up the African east coast of Somalia and then heading back down towards the Seychelles (Filmalter et al., 2012). Overall, the available tagging data demonstrates that oceanic whitetip sharks are capable of traveling great distances in the pelagic environment, but also show a high degree of site fidelity in some locations
tely 6,500 km during the monitored period, moving from the Mozambique Channel up the African east coast of Somalia and then heading back down towards the Seychelles (Filmalter et al., 2012). Overall, the available tagging data demonstrates that oceanic whitetip sharks are capable of traveling great distances in the pelagic environment, but also show a high degree of site fidelity in some locations.
Diet and Feeding
Oceanic whitetip sharks are high trophic-level predators in open ocean ecosystems feeding mainly on teleosts and cephalopods (Backus et al., 1956; Bonfil et al., 2008), but studies have also reported that they consume sea birds, marine mammals, other sharks and rays, molluscs, crustaceans, and even garbage (Compagno 1984; Cortés 1999). Backus et al., (1956) recorded various fish species in the stomachs of oceanic whitetip sharks, including blackfin tuna, barracuda, and white marlin. Based on the species' diet, the oceanic whitetip has a high trophic level, with a score of 4.2 out of a maximum 5.0 (Cortés 1999). The available evidence also suggests that oceanic whitetip sharks are opportunistic feeders. In the Bahamas, large pelagic teleosts ( e.g., billfish, tunas, and dolphin fish) are abundant and oceanic whitetips are anecdotally reported to feed heavily on recreationally caught teleosts in this region. In a recent study of an oceanic whitetip shark aggregation at Cat Island, Bahamas, SIA-based Bayesian mixing model estimates of short-term (near Cat Island) diets showed more large pelagic teleosts (72 percent) than in long-term diets (47 percent), showing a spatiotemporal difference in oceanic whitetip feeding habits. Thus, the availability of large teleost prey and supplemental feeding from recreational sport fishermen may be possible mechanisms underpinning site-fidelity and aggregation of oceanic whitetips at this location (Madigan et al., 2015)
) diets showed more large pelagic teleosts (72 percent) than in long-term diets (47 percent), showing a spatiotemporal difference in oceanic whitetip feeding habits. Thus, the availability of large teleost prey and supplemental feeding from recreational sport fishermen may be possible mechanisms underpinning site-fidelity and aggregation of oceanic whitetips at this location (Madigan et al., 2015).
Size and Growth
Historically, the maximum length effectively measured for the oceanic whitetip was 350 cm total length (TL; Bigelow and Schroder 1948 cited in Lessa et al., 1999), with “gigantic individuals” perhaps reaching 395 cm TL (Compagno 1984), though Compagno's length seems to have never been measured (Lessa et al., 1999). In contemporary times, Lessa et al. (1999) recorded a maximum size of 250 cm TL in the Southwest Atlantic, and estimated a theoretical maximum size of 325 cm TL (Lessa et al., 1999), but the most common sizes are below 300 cm TL (Compagno 1984). The oceanic whitetip has an estimated maximum age of 17 years, with confirmed maximum ages of 12 and 13 years in the North Pacific and South Atlantic, respectively (Seki et al., 1998; Lessa et al., 1999). However, other information from the South Atlantic suggests the species likely lives up to ~20 years old based on observed vertebral ring counts (Rodrigues et al., 2015). Growth rates (growth coefficient, K) have been estimated similarly for both sexes and range from 0.075—0.099 in the Southwest Atlantic to 0.0852-0.103 in the North Pacific (Seki et al., 1998; Lessa et al., 1999; Joung et al., 2016). Using life history parameters from the Southwest Atlantic, Cortés et al. (2010; 2012) estimated productivity of the oceanic whitetip shark, determined as intrinsic rate of population increase ( r ), to be 0.094-0.121 per year (median)
for both sexes and range from 0.075—0.099 in the Southwest Atlantic to 0.0852-0.103 in the North Pacific (Seki et al., 1998; Lessa et al., 1999; Joung et al., 2016). Using life history parameters from the Southwest Atlantic, Cortés et al. (2010; 2012) estimated productivity of the oceanic whitetip shark, determined as intrinsic rate of population increase ( r ), to be 0.094-0.121 per year (median). Overall, the best available data indicate that the oceanic whitetip shark is a long-lived species (at least 20 years) and can be characterized as having relatively low productivity (based on the Food and Agriculture Organization of the United Nations (FAO) productivity indices for exploited fish species, where r < 0.14 is considered low productivity), making them generally vulnerable to depletion and potentially slow to recover from overexploitation.
Reproduction
Similar to other Carcharhinid species, the oceanic whitetip shark is viviparous ( i.e., the species produces live young) with placental embryonic development. The reproductive cycle is thought to be et al., 1998; Bonfil et al., 2008; IOTC 2015a). Age and length of maturity estimates are slightly different depending on geographic location. For example, in the Southwest Atlantic, age and length of maturity in oceanic whitetips was estimated to be 6-7 years and 180-190 cm TL, respectively, for both sexes (Lessa et al., 1999). In the North Pacific, there are two different estimates for age and length of maturity. Seki et al., (1998) estimated that females reach sexual maturity at approximately 168-196 cm TL, and males at 175-189 cm TL, which corresponds to ages of 4 and 5 years, respectively (Seki et al., 1998). However, more recently Joung et al. (2016) determined a later age of maturity in the North Pacific, with females reaching maturity at 190 cm TL (approximately 8.5-8.8 years) and males reaching maturity at 172 cm TL (approximately 6.8-8.9 years old). In the Indian Ocean, both males and females mature at around 190-200 cm TL (IOTC 2014)
nds to ages of 4 and 5 years, respectively (Seki et al., 1998). However, more recently Joung et al. (2016) determined a later age of maturity in the North Pacific, with females reaching maturity at 190 cm TL (approximately 8.5-8.8 years) and males reaching maturity at 172 cm TL (approximately 6.8-8.9 years old). In the Indian Ocean, both males and females mature at around 190-200 cm TL (IOTC 2014). Size at birth also varies slightly between geographic locations, ranging from 55 to 75 cm TL in the North Pacific, around 65-75 cm TL in the northwestern Atlantic, and 60-65 cm TL off South Africa, with reproductive seasons thought to occur from late spring to summer (Bonfil et al., 2008; Compagno 1984).
Tropical Pacific records of pregnant females and newborns are concentrated between 20° N and the equator, from 170° E to 140° W. In the Atlantic, young oceanic whitetip sharks have been found well offshore along the southeastern coast of the United States, suggesting that there may be a nursery in oceanic waters over this continental shelf (Compagno 1984; Bonfil et al., 2008). In the southwestern Atlantic, the prevalence of immature sharks, both female and male, in fisheries catch data suggests that this area may serve as potential nursery habitat for the oceanic whitetip shark (Coelho et al., 2009; Tambourgi et al., 2013; Tolotti et al., 2013; Frédou et al., 2015). Juveniles seem to be concentrated in equatorial latitudes, while specimens in other maturational stages are more widespread (Tambourgi et al., 2013). Pregnant females are often found close to shore, particularly around the Caribbean Islands. One pregnant female was found washed ashore near Auckland, New Zealand. These points suggest that females may come close to shore to pup (Clarke et al., 2015b). In the southwestern Indian Ocean, oceanic whitetip sharks appear to mate and give birth in the early summer. The locations of the nursery grounds are not well known but they are thought to be in oceanic areas
around the Caribbean Islands. One pregnant female was found washed ashore near Auckland, New Zealand. These points suggest that females may come close to shore to pup (Clarke et al., 2015b). In the southwestern Indian Ocean, oceanic whitetip sharks appear to mate and give birth in the early summer. The locations of the nursery grounds are not well known but they are thought to be in oceanic areas.
Population Structure and Genetics
To date, only two studies have been conducted on the genetics and population structure of the oceanic whitetip shark, which suggest there may be some genetic differentiation between various populations of the species. The first study (Camargo et al., 2016) compared the mitochondrial control region (mtCR) in 215 individuals from the Indian Ocean and eastern and western Atlantic Ocean. While results showed significant genetic differentiation (based on haplotype frequencies) between the eastern and western Atlantic Ocean (ΦST = 0.1039, P <0.001; Camargo et al., 2016), pairwise comparisons among populations within the regions revealed a complex pattern. Though some eastern Atlantic populations were significantly differentiated from western Atlantic populations (FST = 0.09−0.27, P < 0.01), others were not (FST = 0.02−0.03, P > 0.01), even after excluding populations with sample sizes of less than 10 individuals (Camargo et al., 2016). Additionally, the sample size from the Indian Ocean (N = 9) may be inadequate to detect statistically significant genetic structure between this and other regions (Camargo et al., 2016). Furthermore, since this study only used mitochondrial markers, male mediated gene flow is not reflected.
In the second study, Ruck (2016) compared the mitochondrial control region, a protein-coding mitochondrial region, and nine nuclear microsatellite loci in 171 individuals sampled from the western Atlantic, Indian, and Pacific Oceans
cture between this and other regions (Camargo et al., 2016). Furthermore, since this study only used mitochondrial markers, male mediated gene flow is not reflected.
In the second study, Ruck (2016) compared the mitochondrial control region, a protein-coding mitochondrial region, and nine nuclear microsatellite loci in 171 individuals sampled from the western Atlantic, Indian, and Pacific Oceans. Using three population-level pairwise metrics (PhiST, FST, and Jost's D), Ruck (2016) did not detect fine-scale matrilineal structure within ocean basins, but mitochondrial and nuclear analyses indicated weak but significant differentiation between western Atlantic and Indo-Pacific Ocean populations (ΦST = 0.076, P = 0.0002; FST = 0.017, P < 0.05 after correction for False Discovery Rate). Therefore, Ruck (2016) suggests that oceanic whitetip sharks consist of a minimum of two contemporary, distinct genetic populations comprising sharks from the western Atlantic and the Indo-Pacific (this study did not have any samples from the eastern Atlantic). However, although significant inter-basin population structure was evident, it was associated with deep phylogeographic mixing of mitochondrial haplotypes and evidence of contemporary migration between the western Atlantic and Indo-Pacific Oceans (Ruck 2016).
As noted previously, although Ruck (2016) did not initially detect fine-scale matrilineal structure within ocean basins, after comparing and analyzing the genetic samples of the two studies together ( i.e., samples from Camargo et al., 2016 and samples from Ruck 2016), Ruck (Unpublished data) detected significant maternal population structure within the western Atlantic that provides evidence of three matrilineal lineages in the western Atlantic. However, the data showing population structure within the Atlantic relies solely on mitochondrial DNA and does not reflect male mediated gene flow
r ( i.e., samples from Camargo et al., 2016 and samples from Ruck 2016), Ruck (Unpublished data) detected significant maternal population structure within the western Atlantic that provides evidence of three matrilineal lineages in the western Atlantic. However, the data showing population structure within the Atlantic relies solely on mitochondrial DNA and does not reflect male mediated gene flow. Thus, while the current (albeit unpublished) data supports three maternal populations within the Atlantic, this data is preliminary and information regarding male mediated gene flow would provide an improved understanding of the fine-scale genetic structuring of oceanic whitetip in the Atlantic.
The best available information indicates that the oceanic whitetip shark has relatively low genetic diversity. Compared to eight other circumtropical elasmobranch species, including the basking shark ( Cetorhinus maximus ), smooth hammerhead ( Sphyrna zygaena ), great hammerhead ( Sphyrna mokarran ), tiger shark ( Galeocerdo cuvier ), blacktip reef shark ( Carcharhinus limbatus ), sandbar shark ( Carcharhinus plumbeus ), silky shark ( Carcharhinus falciformis ), and the whale shark ( Rhincodon typus ), the oceanic whitetip shark ranks the fourth lowest in global mtCR genetic diversity (0.33 percent ± 0.19 percent; Ruck 2016), with diversity similar to the smooth hammerhead (0.32 percent ± 0.18 percent (Testerman 2014) and greater than basking sharks (Hoelzel et al., 2006). The mtCR genetic diversity of the oceanic whitetip is about half that of the closely related silky shark (0.61 percent ±0.32 percent; (Clarke et al., 2015a)) and about a third that of the whale shark (1.1 percent ± 0.6 percent; (Castro et al., 2007). Ruck (2016) noted that the relatively low mtDNA genetic diversity (concatenated mtCR-ND4 nucleotide diversity π = 0.32 percent ±0.17 percent) compared to other circumtropical elasmobranch species raises potential concern for the future genetic health of this species
t ±0.32 percent; (Clarke et al., 2015a)) and about a third that of the whale shark (1.1 percent ± 0.6 percent; (Castro et al., 2007). Ruck (2016) noted that the relatively low mtDNA genetic diversity (concatenated mtCR-ND4 nucleotide diversity π = 0.32 percent ±0.17 percent) compared to other circumtropical elasmobranch species raises potential concern for the future genetic health of this species. Camargo et al., (2016) also observed low levels of et al. 2016).
Current Status
Oceanic whitetip sharks can be found worldwide, with no present indication of a range contraction. Although generally not targeted, they are frequently caught as bycatch in many global fisheries, including pelagic longline (PLL) fisheries targeting tuna and swordfish, purse seine, gillnet, and artisanal fisheries. Oceanic whitetip sharks are also a preferred species for their large, morphologically distinct fins, as they obtain a high price in the Asian fin market, and thus they are valuable as incidental catch for the international shark fin trade.
In 2006, the International Union for Conservation of Nature (IUCN) classified the oceanic whitetip shark as Vulnerable globally based on an assessment by Baum et al., (2006) and its own criteria (A2ad+3d+4ad), and placed the species on its “Red List.” Under criteria A2ad, 3d and 4ad, a species may be classified as Vulnerable when its “observed, estimated, inferred or suspected” population size is reduced by 30 percent or more over the last 10 years, the next 10 years, or any 10-year time period, or over a 3-generation period, whichever is the longer, where the reduction or its causes may not have ceased or may not be understood or may not be reversible, based on a direct observation and actual or potential levels of exploitation. The IUCN's justification for the categorization is based on the species' declining populations
the last 10 years, the next 10 years, or any 10-year time period, or over a 3-generation period, whichever is the longer, where the reduction or its causes may not have ceased or may not be understood or may not be reversible, based on a direct observation and actual or potential levels of exploitation. The IUCN's justification for the categorization is based on the species' declining populations. The IUCN notes that the species' regional trends, slow life history characteristics (hence low capacity to recover from moderate levels of exploitation), and high levels of largely unmanaged and unreported mortality in target and bycatch fisheries, give cause to suspect that the population has decreased by over 30 percent and meets the criteria to be categorized as Vulnerable globally. As a note, the IUCN classification for the oceanic whitetip shark alone does not provide the rationale for a listing recommendation under the ESA, but the classification and the sources of information that the classification is based upon are evaluated in light of the standards on extinction risk and impacts or threats to the species.
Distinct Population Segments
As described above, the ESA's definition of “species” includes “any subspecies of fish or wildlife or plants, and any distinct population segment (DPS) of any species of vertebrate fish or wildlife which interbreeds when mature.” As stated in the joint DPS policy, Congress expressed its expectation that the Services would exercise authority with regard to DPSs sparingly and only when the biological evidence indicates such action is warranted. NMFS determined at the 90-day finding stage that the petition to list the global species of oceanic whitetip shark was warranted. As such, we conducted the extinction risk analysis on the global oceanic whitetip shark population
xpressed its expectation that the Services would exercise authority with regard to DPSs sparingly and only when the biological evidence indicates such action is warranted. NMFS determined at the 90-day finding stage that the petition to list the global species of oceanic whitetip shark was warranted. As such, we conducted the extinction risk analysis on the global oceanic whitetip shark population.
Assessment of Extinction Risk
The ESA (section 3) defines an endangered species as “any species which is in danger of extinction throughout all or a significant portion of its range.” A threatened species is defined as “any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.” Neither we nor the USFWS have developed formal policy guidance about how to interpret the definitions of threatened and endangered with respect to what it means to be “in danger of extinction.” We consider the best available information and apply professional judgment in evaluating the level of risk faced by a species in deciding whether the species is threatened or endangered. We evaluate both demographic risks, such as low abundance and productivity, and threats to the species, including those related to the factors specified in ESA section 4(a)(1)(A)-(E).
Methods
As we described previously, we convened an ERA team to evaluate extinction risk to the species. This section discusses the methods used to evaluate threats and the overall extinction risk to the oceanic whitetip shark. For purposes of the risk assessment, an ERA team comprised of fishery biologists and shark experts was convened to review the best available information on the species and evaluate the overall risk of extinction facing the oceanic whitetip shark, now and in the foreseeable future. The term “foreseeable future” was defined as the timeframe over which threats could be reliably predicted to impact the biological status of the species
t, an ERA team comprised of fishery biologists and shark experts was convened to review the best available information on the species and evaluate the overall risk of extinction facing the oceanic whitetip shark, now and in the foreseeable future. The term “foreseeable future” was defined as the timeframe over which threats could be reliably predicted to impact the biological status of the species. After considering the life history of the oceanic whitetip shark, availability of data, and types of threats, the ERA team decided that the foreseeable future should be defined as approximately 3 generation times for the oceanic whitetip shark, or approximately 30 years. A generation time is defined as the time it takes, on average, for a sexually mature female oceanic whitetip shark to be replaced by offspring with the same spawning capacity. This timeframe (3 generation times) takes into account the time necessary to provide for the conservation and recovery of the species. As a late-maturing species, with slow growth rate and relatively low productivity, it would likely take more than a generation time for any conservative management action to be realized and reflected in population abundance indices. In addition, the foreseeable future timeframe is also a function of the reliability of available data regarding the identified threats and extends only as far as the data allow for making reasonable predictions about the species' response to those threats. Since the main threats to the species were identified as fisheries and the inadequacy of existing regulatory measures that manage these fisheries, the ERA team felt that they had the background knowledge in fisheries management and expertise to confidently predict the impact of these threats on the biological status of the species within this timeframe.
The ability to measure or document risk factors to a marine species is often limited, where quantitative estimates of abundance and life history information are often lacking altogether
es, the ERA team felt that they had the background knowledge in fisheries management and expertise to confidently predict the impact of these threats on the biological status of the species within this timeframe.
The ability to measure or document risk factors to a marine species is often limited, where quantitative estimates of abundance and life history information are often lacking altogether. Therefore, in assessing extinction risk of a data limited species, it is important to include both qualitative and quantitative information. In assessing extinction risk to the oceanic whitetip shark, the ERA team considered the demographic viability factors developed by McElhany et al., (2000) and the risk matrix approach developed by Wainwright and Kope (1999) to organize and summarize extinction risk considerations. The approach of considering demographic risk factors to help frame the consideration of extinction risk has been used in many of our status reviews (see http://www.nmfs.noaa.gov/pr/species for links to these reviews). In this approach, the collective condition of individual populations is considered at the species level according to four demographic viability factors: Abundance, growth rate/productivity, spatial structure/connectivity, and diversity. These viability factors reflect concepts that are
Using these concepts, the ERA team evaluated demographic risks by assigning a risk score to each of the four demographic risk factors. The scoring for these demographic risk criteria correspond to the following values: 0—unknown risk, 1—low risk, 2—moderate risk, and 3—high risk. Detailed definitions of the risk scores can be found in the status review report.
The ERA team also performed a threats assessment for the oceanic whitetip shark by evaluating the effect that the threat was currently having on the extinction risk of the species. The levels included “unknown,” “low,” “moderate,” and “high.” The scores were then tallied and summarized for each threat
3—high risk. Detailed definitions of the risk scores can be found in the status review report.
The ERA team also performed a threats assessment for the oceanic whitetip shark by evaluating the effect that the threat was currently having on the extinction risk of the species. The levels included “unknown,” “low,” “moderate,” and “high.” The scores were then tallied and summarized for each threat. It should be emphasized that this exercise was simply a tool to help the ERA team members organize the information and assist in their thought processes for determining the overall risk of extinction for the oceanic whitetip shark.
Guided by the results from the demographic risk analysis and the threats assessment, the ERA team members were asked to use their informed professional judgment to make an overall extinction risk determination for the oceanic whitetip shark. For this analysis, the ERA team considered three levels of extinction risk: 1—low risk, 2—moderate risk, and 3—high risk, which are all temporally connected. Detailed definitions of these risk levels are as follows: 1 = Low risk: A species or DPS is at low risk of extinction if it is not at a moderate or high level of extinction risk (see “Moderate risk” and “High risk” below). A species or DPS may be at a low risk of extinction if it is not facing threats that result in declining trends in abundance, productivity, spatial structure, or diversity. A species or DPS at low risk of extinction is likely to show stable or increasing trends in abundance and productivity with connected, diverse populations; 2 = Moderate risk: A species or DPS is at moderate risk of extinction if it is on a trajectory that puts it at a high level of extinction risk in the foreseeable future (see description of “High risk”). A species or DPS may be at moderate risk of extinction due to projected threats or declining trends in abundance, productivity, spatial structure, or diversity
with connected, diverse populations; 2 = Moderate risk: A species or DPS is at moderate risk of extinction if it is on a trajectory that puts it at a high level of extinction risk in the foreseeable future (see description of “High risk”). A species or DPS may be at moderate risk of extinction due to projected threats or declining trends in abundance, productivity, spatial structure, or diversity. The appropriate time horizon for evaluating whether a species or DPS is more likely than not to be at high risk in the foreseeable future depends on various case- and species-specific factors; 3 = High risk: A species or DPS with a high risk of extinction is at or near a level of abundance, productivity, spatial structure, and/or diversity that places its continued persistence in question. The demographics of a species or DPS at such a high level of risk may be highly uncertain and strongly influenced by stochastic or depensatory processes. Similarly, a species or DPS may be at high risk of extinction if it faces clear and present threats ( e.g., confinement to a small geographic area; imminent destruction, modification, or curtailment of its habitat; or disease epidemic) that are likely to create present and substantial demographic risks. The ERA team adopted the “likelihood point” (FEMAT) method for ranking the overall risk of extinction to allow individuals to express uncertainty. For this approach, each team member distributed 10 “likelihood points” among the extinction risk levels. This approach has been used in previous NMFS status reviews ( e.g., Pacific salmon, Southern Resident killer whale, Puget Sound rockfish, Pacific herring, and black abalone) to structure the team's thinking and express levels of uncertainty when assigning risk categories. Although this process helps to integrate and summarize a large amount of diverse information, there is no simple way to translate the risk matrix scores directly into a determination of overall extinction risk
, Southern Resident killer whale, Puget Sound rockfish, Pacific herring, and black abalone) to structure the team's thinking and express levels of uncertainty when assigning risk categories. Although this process helps to integrate and summarize a large amount of diverse information, there is no simple way to translate the risk matrix scores directly into a determination of overall extinction risk. Other descriptive statistics, such as mean, variance, and standard deviation, were not calculated, as the ERA team felt these metrics would add artificial precision to the results. The scores were then tallied and summarized.
Finally, the ERA team did not make recommendations as to whether the species should be listed as threatened or endangered. Rather, the ERA team drew scientific conclusions about the overall risk of extinction faced by the oceanic whitetip shark under present conditions and in the foreseeable future based on an evaluation of the species' demographic risks and assessment of threats.
Evaluation of Demographic Risks
Abundance
While a global population size estimate or trend for the oceanic whitetip shark is currently unavailable, numerous sources of information, including the results of a recent stock assessment and several other abundance indices ( e.g., trends in occurrence and composition in fisheries catch data, catch-per-unit-effort (CPUE), and biological indicators) were available to infer and assess current regional abundance trends of the species. Given the available data, and the fact that the available assessments were not conducted prior to the advent of industrial fishing (and thus not from virgin biomass), the exact magnitude of the declines and current abundance of the global population are unknown
ch-per-unit-effort (CPUE), and biological indicators) were available to infer and assess current regional abundance trends of the species. Given the available data, and the fact that the available assessments were not conducted prior to the advent of industrial fishing (and thus not from virgin biomass), the exact magnitude of the declines and current abundance of the global population are unknown. However, based on the best available scientific and commercial data, the ERA team concluded, and we agree, that while the oceanic whitetip shark was historically one of the most abundant and ubiquitous shark species in tropical seas around the world, numerous lines of evidence suggest the species has not only undergone significant historical declines throughout its range, but likely continues to experience abundance declines of varying magnitude globally.
Across the Pacific Ocean, several lines of evidence indicate significant and ongoing population declines of the oceanic whitetip shark. In the eastern Pacific Ocean (EPO), the oceanic whitetip shark was historically the third most abundant shark species after blue sharks ( Prionace glauca ) and silky sharks ( C. falciformis ). The oceanic whitetip comprised approximately 20 percent of the total shark catch in the tropical tuna purse seine fishery from 2000-2001 (Roman-Verdesoto and Orozco-Zoller 2005) and averaged 9 percent of the total shark catch from 1993-2009 (with silky sharks comprising 84 percent, the hammerhead complex comprising 5 percent, and other sharks comprising 2 percent; Hall and Román 2013). However, if only the more recent period from 2005-2009 is considered, then the proportion of silky sharks is 93 percent, followed by the scalloped hammerhead shark (1.6 percent), and the smooth hammerhead shark (1.5 percent). The changes are the result of a rapid decline in oceanic whitetip sharks (Hall and Román 2013)
prising 5 percent, and other sharks comprising 2 percent; Hall and Román 2013). However, if only the more recent period from 2005-2009 is considered, then the proportion of silky sharks is 93 percent, followed by the scalloped hammerhead shark (1.6 percent), and the smooth hammerhead shark (1.5 percent). The changes are the result of a rapid decline in oceanic whitetip sharks (Hall and Román 2013). Data for the oceanic whitetip shark in the EPO is available from the Inter-American Tropical Tuna Commission (IATTC), the Regional Fishery Management Organization (RFMO) responsible for the conservation and management of tuna and tuna-like species in the IATTC Convention Area. The IATTC Convention Area is defined as waters of the EPO within the area bounded by the west coast of the Americas and by 50° N. latitude, 150° W. longitude, and 50° S. latitude.
Nominal catch data from the IATTC shows that purse seine sets on floating objects, unassociated sets and dolphin sets all show decreasing trends of oceanic whitetip shark since 1994 (IATTC 2007). In particular, presence of oceanic whitetip sharks on sets with floating objects, which are responsible
Similar levels of decline have also been observed across the Western and Central Pacific Ocean. Like the eastern Pacific, the oceanic whitetip shark was once one of the most abundant pelagic shark species throughout the tropical waters of the region. For example, tuna longline survey data from the 1950s indicate oceanic whitetip sharks comprised 28 percent of the total shark catch of fisheries south of 10° N. (Strasburg 1958). Likewise, Japanese research longline records during 1967-1968 indicate that oceanic whitetip sharks were among the most common shark species taken by tuna vessels in tropical seas of the Western and Central Pacific, and comprised 22.5 percent and 23.5 percent of the total shark catch west and east of the International Date Line, respectively (Taniuchi 1990)
heries south of 10° N. (Strasburg 1958). Likewise, Japanese research longline records during 1967-1968 indicate that oceanic whitetip sharks were among the most common shark species taken by tuna vessels in tropical seas of the Western and Central Pacific, and comprised 22.5 percent and 23.5 percent of the total shark catch west and east of the International Date Line, respectively (Taniuchi 1990). However, numerous sources of information indicate significant and ongoing abundance declines of oceanic whitetip sharks in this region. For example, a recent stock assessment conducted in the Western and Central Pacific, based on observer data from the Secretariat of the Pacific Community (SPC), estimated an 86 percent decline in spawning biomass from 1995 to 2009, with total biomass reduced to just 6.6 percent of the theoretical equilibrium virgin biomass ( i.e., a total decline of 93.4 percent; Rice and Harley 2012). Based on the results from the oceanic whitetip stock assessment, the median estimate of oceanic whitetip biomass in the Western Central Pacific as of 2010 was 7,295 tons (Rice and Harley 2012), which would be equivalent to a population of roughly 200,000 individuals (FAO 2012). An updated assessment analyzing various abundance indices, including standardized CPUE, concluded that the oceanic whitetip shark continues to decline throughout the tropical waters of the Western and Central Pacific (Rice et al., 2015), indicating a severely depleted population of oceanic whitetip shark across the region with observations of the species becoming increasingly rare. Similar results were found in analyses of CPUE data from the Hawaii-based PLL fishery, where oceanic whitetip shark showed a decline in relative abundance on the order of ≥90 percent from 1995-2010 (Clarke et al., 2012; Brodziak et al., 2013)
l., 2015), indicating a severely depleted population of oceanic whitetip shark across the region with observations of the species becoming increasingly rare. Similar results were found in analyses of CPUE data from the Hawaii-based PLL fishery, where oceanic whitetip shark showed a decline in relative abundance on the order of ≥90 percent from 1995-2010 (Clarke et al., 2012; Brodziak et al., 2013). It must be recognized that the closeness of the agreement between the trends in observer data from Hawaii and the observer data from the SPC for the entire Western and Central Pacific Ocean may be partly due to the use of datasets that partially overlap for years prior to 2005. Still, even after 2005, the trends show similar results suggesting that the patterns are representative of regional trends in oceanic whitetip abundance. A preliminary update of the Brodziak et al. (2013) study with 4 additional years of data (2011-2014) indicates a potential relative stability in the population size at a post-decline depressed state (Young et al., 2016). Nonetheless, the ERA team concluded, and we agree, that the levels of significant and ongoing population decline observed in these studies indicate that these declines are not just local or regional, but rather a Pacific-wide phenomenon, with no significant indication that these trends have reversed.
In the Northwest Atlantic, the oceanic whitetip shark was described historically as widespread, abundant, and the most common pelagic shark in the warm parts of the North Atlantic (Backus et al., 1956). Several studies have been conducted to determine trends in abundance of various shark species, including the oceanic whitetip shark. Baum et al., (2003) analyzed logbook data for the U.S. PLL fleets targeting swordfish and tunas, and reported a 70 percent decline in relative abundance for the oceanic whitetip shark from 1992 to 2000
rk in the warm parts of the North Atlantic (Backus et al., 1956). Several studies have been conducted to determine trends in abundance of various shark species, including the oceanic whitetip shark. Baum et al., (2003) analyzed logbook data for the U.S. PLL fleets targeting swordfish and tunas, and reported a 70 percent decline in relative abundance for the oceanic whitetip shark from 1992 to 2000. Similarly, Baum and Myers (2004) compared longline CPUE from research surveys from 1954-1957 to observed commercial longline sets from 1995-1999, and determined that the oceanic whitetip had declined by more than 150-fold, or 99.3 percent (95 percent; Confidence Interval (CI): 98.3-99.8 percent) in the Gulf of Mexico during that time. However, the methods and results of Baum et al. (2003) and Baum and Myers (2004) were challenged on the basis of whether correct inferences were made regarding the magnitude of shark population declines in the Atlantic (see discussions in Burgess et al., (2005b) and Burgess et al., (2005a)). Of particular relevance to the oceanic whitetip, Burgess et al., (2005b) noted that the change from steel to monofilament leaders between the 1950s and 1990s could have reduced the catchability of all large sharks, and the increase in the average depth of sets during the same period could have reduced the catchability of the surface-dwelling oceanic whitetip (FAO 2012). Later, Driggers et al., (2011) conducted a study on the effects of different leader materials on the CPUE of oceanic sharks and determined that with equivalent methods but using a wire leader, the catch rates of Baum and Myers (2004) for the recent period would have been 0.55 rather than 0.02 (as estimated by Baum and Myers (2004) using nylon leaders). Comparing the recent 0.55 value with the Baum et al. (2003) value of 4.62 for the 1950s gave an estimated extent of decline of 88 percent (FAO 2012). In a re-analysis of the same logbook dataset analyzed by Baum et al
using a wire leader, the catch rates of Baum and Myers (2004) for the recent period would have been 0.55 rather than 0.02 (as estimated by Baum and Myers (2004) using nylon leaders). Comparing the recent 0.55 value with the Baum et al. (2003) value of 4.62 for the 1950s gave an estimated extent of decline of 88 percent (FAO 2012). In a re-analysis of the same logbook dataset analyzed by Baum et al. (2003) for the Northwest Atlantic using a similar methodology, Cortés et al., (2007) reported a 57 percent decline from 1992-2005. The decline was largely driven by a 37 percent decline from 1992 to 1993 and a subsequent decline of 53 percent from 1997 to 2000, after which the time series remained stable (2000-2005). However, an analysis of the observer dataset from the same fishery resulted in a less pronounced decline than that of the logbook analysis, with a 9 percent decline in abundance from the same period of 1992-2005. Finally, the ERA team conducted an updated analysis (1992-2015) using the same observer data analyzed by Cortés et al. (2007). Similar to previous analyses, there was high variability in the initial years of the time series, but overall, the analysis conducted by the ERA team showed ~4 percent decline over the time series, with the overall trend indicative that the population may have stabilized (Young et al. 2016). Although observer data are generally regarded as more reliable than logbook data for non-target shark species (Walsh et al., 2002), it should be noted that the sample size of oceanic whitetip shark in the observer data was substantially smaller than for other species, and thus the trends estimated should be regarded with caution. Additionally, although misreporting and species misidentification are likely to be much more prevalent in logbooks, Carcharhinus species
logbook data for non-target shark species (Walsh et al., 2002), it should be noted that the sample size of oceanic whitetip shark in the observer data was substantially smaller than for other species, and thus the trends estimated should be regarded with caution. Additionally, although misreporting and species misidentification are likely to be much more prevalent in logbooks, Carcharhinus species. It should also be noted that fishing pressure on the oceanic whitetip shark began decades prior to the time series covered in these studies (with the exception of the Baum and Myers (2004) study), thus the percentage declines discussed here do not represent percentage declines from historical virgin biomass. Therefore, given all of the caveats and limitations of the studies and analyses discussed above, it is likely that the oceanic whitetip shark population in the Northwest Atlantic and Gulf of Mexico experienced significant historical declines; however, relative abundance of oceanic whitetip shark may have stabilized in the Northwest Atlantic since 2000 and in the Gulf of Mexico/Caribbean since the late 1990s at a significantly diminished abundance (Cortés et al. 2007; Young et al. 2016).
In other areas of the oceanic whitetip shark range, robust and reliable quantitative abundance data are limited or lacking altogether. In the South Atlantic, the oceanic whitetip has been characterized as one of the most abundant species of pelagic shark in the southwestern and equatorial region. For example, the oceanic whitetip was the third most commonly caught shark out of 33 shark species caught year-round in the prominent Brazilian Santos longline fishery, and one of 7 species that comprised >5 percent of total shark catches from 1971-1995 (Amorim 1998). In Itajai, southern Brazil, oceanic whitetip sharks were considered “abundant” and “frequent” in the surface longline and gillnet fleets, respectively, from 1994-1999 (Mazzoleni and Schwingel 1999)
ht shark out of 33 shark species caught year-round in the prominent Brazilian Santos longline fishery, and one of 7 species that comprised >5 percent of total shark catches from 1971-1995 (Amorim 1998). In Itajai, southern Brazil, oceanic whitetip sharks were considered “abundant” and “frequent” in the surface longline and gillnet fleets, respectively, from 1994-1999 (Mazzoleni and Schwingel 1999). Likewise, in equatorial waters off the northeastern coast of Brazil, the oceanic whitetip shark was historically reported as the second most abundant elasmobranch species, outnumbered only by the blue shark ( P. glauca ), in research surveys conducted within the EEZ of Brazil, and comprised 29 percent of the total elasmobranch catch in the 1990s (Lessa et al., 1999). From 1992-2002, oceanic whitetip CPUE in this area averaged 2.18 individuals/1,000 hooks (Domingo et al., 2007); more recently, however, the average CPUE recorded in this same area from 2004-2010 of 0.1-0.3 individuals/1,000 hooks (Frédou et al., 2015) is much lower. Additionally, none of the other areas within this region exhibit CPUE rates comparable to the rates seen in the 1990s. Further, demographic analyses from the largest oceanic whitetip shark catching country in the South Atlantic ( i.e., Brazil) indicate abundance declines similar to the Northwest Atlantic of 50-79 percent in recent decades (Santana et al., 2004; ICMBio 2014) and coincide with significant declines in catches of oceanic whitetip shark reported by Brazil to the International Commission for the Conservation of Atlantic Tunas (ICCAT). As a result of these declining trends, the oceanic whitetip shark was designated as a “species threatened by overexploitation” in 2004 by Brazil's Ministério do Meio Ambiente (Ministry of Environment), and listed under Annex II of Brazil's Normative Ruling No. 5 of May 21, 2004 that recognizes endangered species and species threatened by overexploitation, including aquatic invertebrates and fish
. As a result of these declining trends, the oceanic whitetip shark was designated as a “species threatened by overexploitation” in 2004 by Brazil's Ministério do Meio Ambiente (Ministry of Environment), and listed under Annex II of Brazil's Normative Ruling No. 5 of May 21, 2004 that recognizes endangered species and species threatened by overexploitation, including aquatic invertebrates and fish. In 2014, Brazil finalized its national assessment regarding the extinction risk of Brazilian fauna, and listed the oceanic whitetip shark as Vulnerable under Brazil's “Lista Nacional Oficial de Espécies da Fauna Ameaçadas de Extinção—Peixes e Invertebrados Aquáticos” (National Official List of Endangered Species of Fauna—Fish and Aquatic Invertebrate; ICMBio 2014).
Elsewhere across the South Atlantic, the oceanic whitetip shark appears to be relatively rare, with low patchy abundance. For example, in 6 years of observer data from the Uruguayan longline fleet (1998-2003), catches of oceanic whitetip shark were described as “occasional” with CPUE rates of only 0.006 individuals/1,000 hooks (Domingo 2004). However, during this study, the Uruguayan longline fleet operated between latitudes 26° and 37° S. and within sea surface temperatures ranging between 16° and 23 °C, which are largely lower than the temperature preferences of the species. Domingo (2004) noted that it is unknown whether the species has always occurred in low numbers in this region of the South Atlantic, or whether the population has been affected significantly by fishing effort. More recently, Domingo et al. (2007) found similar results, with the highest CPUE recorded not exceeding 0.491 individuals/1,000 hooks. In total, only 63 oceanic whitetips were caught on 2,279,169 hooks and 63 percent were juveniles. All catches occurred in sets with sea surface temperatures ≥22.5 °C (Domingo et al., 2007)
r whether the population has been affected significantly by fishing effort. More recently, Domingo et al. (2007) found similar results, with the highest CPUE recorded not exceeding 0.491 individuals/1,000 hooks. In total, only 63 oceanic whitetips were caught on 2,279,169 hooks and 63 percent were juveniles. All catches occurred in sets with sea surface temperatures ≥22.5 °C (Domingo et al., 2007). Again, this data does not indicate whether a decline in the population has occurred, rather, it clearly reflects the low abundance of the species in this area (Domingo et al., 2007). The low abundance of oceanic whitetip in this area may be the result of the species' tendency to remain in warmer, tropical waters farther north. Alternatively, it could be a result of historical fishing pressure in the region.
Finally, in a study that synthesized information on shark catch rates (based on 871,177 sharks caught on 86,492 longline sets) for the major species caught by multiple fleets in the South Atlantic between 1979 and 2011, catch rates of most species (with the exception of P. glauca and A. superciliosus ), including oceanic whitetip, declined by more than 85 percent (Barreto et al., 2015). However, it should be noted that there are some caveats and limitations to this study, including high and overlapping confidence intervals, raising the possibility that the trends may be noise rather than truly tracking abundance. Nonetheless, while robust abundance data is lacking in the South Atlantic, the best available information, including demographic analyses and fisheries data across the region from 1979-2011, indicate the oceanic whitetip shark has potentially experienced a significant population decline ranging from 50-85 percent (Santana et al. 2004; ICMBio 2014; Barreto et al. 2015)
han truly tracking abundance. Nonetheless, while robust abundance data is lacking in the South Atlantic, the best available information, including demographic analyses and fisheries data across the region from 1979-2011, indicate the oceanic whitetip shark has potentially experienced a significant population decline ranging from 50-85 percent (Santana et al. 2004; ICMBio 2014; Barreto et al. 2015). Overall, the ERA team concluded, and we agree, that the oceanic whitetip population in the South Atlantic has likely experienced historical declines similar to levels seen in the Northwest Atlantic, and this population decline is likely ongoing, although we acknowledge some uncertainty regarding the available data from this region.
Abundance information from the Indian Ocean is relatively deficient and unreliable. Nonetheless, historical research data shows overall declines in both CPUE and mean weight of oceanic whitetip sharks (Romanov et al., 2008), and anecdotal reports suggest that oceanic whitetips have become rare throughout much of the Indian Ocean over the past 20 years (IOTC 2015a). The Indian Ocean Tuna Commission (IOTC) also reports that despite limited data, oceanic whitetip shark abundance has likely declined significantly over recent decades. Furthermore, a few quantitative studies provide some additional information indicative of declining trends of oceanic whitetip in the Indian Ocean. For example, data from an exploratory fishing survey for large pelagic species conducted off the eastern seaboard of the Maldives from 1987-1988 reported that oceanic whitetips represented 29 percent of the sharks caught by longline and 10 percent of the sharks caught by gillnet in all fishing zones (Anderson and Waheed 1990). During this survey, the et al. (2011) estimated that the average CPUE of oceanic whitetip in the shark longline fishery was only 0.20 individuals per fishing vessel (or approximately 0.14 sharks/100 hooks), and estimated the species contributed only 3.5 percent of the shark landings
s caught by longline and 10 percent of the sharks caught by gillnet in all fishing zones (Anderson and Waheed 1990). During this survey, the et al. (2011) estimated that the average CPUE of oceanic whitetip in the shark longline fishery was only 0.20 individuals per fishing vessel (or approximately 0.14 sharks/100 hooks), and estimated the species contributed only 3.5 percent of the shark landings. This would represent a 90 percent decline in abundance between 1987-1988 and 2000-2004. Such a level of decline would be consistent with the decrease in the proportion of oceanic whitetip in the catch (from 29 percent of longline shark catch in 1987-1988 to just 3.5 percent of landings in 2000-2004) and also with anecdotal information reporting a marked decrease in sightings of oceanic whitetip sharks off northern and central Maldives (Anderson et al., 2011; FAO 2012). The IOTC Working Party on Ecosystems and Bycatch (WPEB) noted the following on the aforementioned studies: “Data collected on shark abundance represents a consistent time series for the periods 1987-1988 and 2000-2004, collected with similar longline gear, and that the data was showing a declining trend in oceanic whitetip shark abundance, which is a potential indicator of overall stock depletion.” The WPEB further noted that it could be related to localized effects, although this was deemed unlikely as oceanic whitetip sharks are wide-ranging and abundance trends from long-term research conducted by the former Soviet Union between the 1960s and 1980s indicate a similar decline of oceanic whitetip sharks, and that “sightings of this species in Maldives and Réunion islands is now quite uncommon” (IOTC 2011).
Similarly, surveys of the tuna longline fishery in India indicate a likely decline of oceanic whitetip shark abundance
de-ranging and abundance trends from long-term research conducted by the former Soviet Union between the 1960s and 1980s indicate a similar decline of oceanic whitetip sharks, and that “sightings of this species in Maldives and Réunion islands is now quite uncommon” (IOTC 2011).
Similarly, surveys of the tuna longline fishery in India indicate a likely decline of oceanic whitetip shark abundance. In Andaman and Nicobar waters, where catches of sharks are prominent and contribute 35.15 percent of the catch by number and 51.46 percent by weight, John and Varghese (2009) reported that the oceanic whitetip shark comprised 4.6 percent of the total shark catch from 1984-2006. However, in more recent surveys, Varghese et al., (2015) report that oceanic whitetip shark comprised only 0.23 percent of the total shark catch from 2004-2010 in this area, which is significantly lower than what John and Varghese (2009) reported previously. Off the West Coast of India in the eastern Arabian Sea, the percentage of oceanic whitetip sharks in the overall shark catch also declined slightly from 0.6 percent to 0.45 percent. Overall, Varghese et al. (2015) shows that the index of relative abundance of sharks was considerably lower than that found in earlier studies, indicating a decline in abundance over the years. While the lack of standardized CPUE trend information for oceanic whitetip in these studies makes it difficult to evaluate the potential changes in abundance for this species in this region, based on the best available information, it is likely that the oceanic whitetip has experienced some level of population decline in this region. Additionally, it is important to note that India has objected to IOTC Resolution 13-06, which prohibits the retention of oceanic whitetip sharks (since 2013) in IOTC managed fisheries, and thus this Resolution is not binding on India. Therefore, oceanic whitetip sharks may still be retained in Indian fisheries
at the oceanic whitetip has experienced some level of population decline in this region. Additionally, it is important to note that India has objected to IOTC Resolution 13-06, which prohibits the retention of oceanic whitetip sharks (since 2013) in IOTC managed fisheries, and thus this Resolution is not binding on India. Therefore, oceanic whitetip sharks may still be retained in Indian fisheries.
Other studies on the abundance trends of oceanic whitetip shark in the Indian Ocean, including analyses of standardized CPUE indices from Japanese and Spanish longline fisheries, also indicate potential population declines, although trends are conflicting. Two studies estimate standardized CPUE for oceanic whitetip shark in the Japanese longline fleet operating in the Indian Ocean (Semba and Yokawa 2011; Yokawa and Semba 2012). In the first 2011 study, CPUE reached its peak in 2003 and then showed a gradually decreasing trend thereafter. Prior to 2003, large fluctuations in oceanic whitetip CPUE are attributed to changes in reporting requirements rather than the actual trend of the stock, as those years represent the introduction phase of a new recording system. The data showed low values in 2000 and 2001 (attributed to extremely low catches), and a gradual decreasing trend from 2003 to 2009. The authors interpreted a 40 percent decline in CPUE as an indication of a decrease in abundance of the population (FAO 2012; Semba and Yokawa 2011). Yokawa and Semba (2012) updated the data to 2011 using a modified data filtering method, which produced a rather similar and somewhat flattened trend.
Standardized CPUE of the Spanish longline fishery from 1998 to 2011 showed large historical fluctuations and a general decreasing trend of oceanic whitetip shark from 1998-2007, followed by an increase thereafter in the last 4 years of the time series
wa and Semba (2012) updated the data to 2011 using a modified data filtering method, which produced a rather similar and somewhat flattened trend.
Standardized CPUE of the Spanish longline fishery from 1998 to 2011 showed large historical fluctuations and a general decreasing trend of oceanic whitetip shark from 1998-2007, followed by an increase thereafter in the last 4 years of the time series. Overall, the magnitude of decline in this study was estimated to be about 25-30 percent (Ramos-Cartelle et al., 2012); however, it should be noted that due to the high variability of the standardized catch rates between consecutive years and limited availability of specimens in some years, this index could be representative of a particular period rather than a plausible indicator of the stock abundance at large (Ramos-Cartelle et al., 2012). Specifically, the data yielded support for the relatively low prevalence described for this species in the commercial fishery of surface longline fleets targeting swordfish in waters with temperatures generally lower than those selected by this species as its preferred habitat (García-Cortés et al., 2012; Ramos-Cartelle et al., 2012).
Finally, a study that incorporated data from the tropical French and Soviet Union purse seine fisheries analyzed the interaction between oceanic whitetip sharks and the tropical purse seine fisheries in terms of occurrence per set (not taking into account the number of individuals caught per set) from the mid-1980s to 2014. Results showed a marked change in the proportion of fish aggregating device (FAD) sets with oceanic whitetips present, fluctuating around 20 percent in the mid-1980s and 1990s, and then dropping to less than 10 percent from 2005 onwards
nd the tropical purse seine fisheries in terms of occurrence per set (not taking into account the number of individuals caught per set) from the mid-1980s to 2014. Results showed a marked change in the proportion of fish aggregating device (FAD) sets with oceanic whitetips present, fluctuating around 20 percent in the mid-1980s and 1990s, and then dropping to less than 10 percent from 2005 onwards. Taking into account that the number of FADs has greatly increased since the 1990s (Dagorn et al., 2013; Maufroy et al., 2015; Tolotti et al., 2015b), the change in the proportion of FADs with oceanic whitetip sharks by more than 50 percent could indicate an important population decline (Tolotti et al., 2015b). Alternatively, the decline of oceanic whitetip shark occurrence per FAD could be the result of a sharp increase of FAD densities combined with a small and stable population size. In this scenario, the proportion of oceanic whitetips/FAD would simply decrease because there aren't enough sharks to aggregate around that many FADs. However, although the analyzed data does not provide a straightforward interpretation (as both hypotheses seem plausible), given the declines indicated in other studies throughout the Indian Ocean, it seems more plausible that the marked decline observed in Tolotti et al. (2015b) is indicative of a declining abundance trend rather than a small, stable population.
Despite the varying magnitudes of reported declines of oceanic whitetip shark in the Indian Ocean, the ERA team agreed that given the significantly high fishing pressure and catches of oceanic whitetip shark in the Indian Ocean (which are likely severely underreported), combined with the Overutilization for Commercial, Recreational, Scientific, or Educational Purposes section below for more details), it is likely that the species will continue to experience population declines in this region into the foreseeable future
given the significantly high fishing pressure and catches of oceanic whitetip shark in the Indian Ocean (which are likely severely underreported), combined with the Overutilization for Commercial, Recreational, Scientific, or Educational Purposes section below for more details), it is likely that the species will continue to experience population declines in this region into the foreseeable future.
Overall, in areas where oceanic whitetip shark data are available, trends from throughout the species' global range show large historical declines in abundance ( e.g., Eastern Pacific, Western and Central Pacific, Atlantic and Indian Oceans). Recent evidence suggests that most populations are still experiencing various levels of decline due to continued fishing pressure and associated mortality. Further, the potential stabilization of the abundance trends at depleted levels seen in observer data from the Northwest Atlantic and Hawaiian PLL fisheries represents a small contingent of the global population. Thus, the best available scientific and commercial data available suggest that the global population of oceanic whitetip continues to experience various levels of decline throughout the majority of its range.
Growth Rate/Productivity
The ERA team expressed some concern regarding the effect of the oceanic whitetip shark's growth rate and productivity on its risk of extinction. Sharks, in general, have lower reproductive and growth rates compared to bony fishes. The ERA team noted that this species has some life history parameters that are typically advantageous, and some that are likely detrimental to the species' resilience to excessive levels of exploitation. For example, in comparison to other shark species, the oceanic whitetip is relatively productive, with an intrinsic rate of population increase (r) of 0.094-0.121 per year (Cortés 2010; 2012)
hes. The ERA team noted that this species has some life history parameters that are typically advantageous, and some that are likely detrimental to the species' resilience to excessive levels of exploitation. For example, in comparison to other shark species, the oceanic whitetip is relatively productive, with an intrinsic rate of population increase (r) of 0.094-0.121 per year (Cortés 2010; 2012). The oceanic whitetip also ranked among the highest in productivity when compared with other pelagic shark species in terms of its pup production, rebound potential, potential for population increase, and for its stochastic growth rate (Chapple and Botsford 2013). Although the oceanic whitetip shark has a relatively high productivity rate compared to other sharks, it is still considered low for a fish species (r <0.14). Additionally, the species has a fairly late age of maturity (~6-9 years for females depending on the location), has a lengthy gestation period of 9-12 months, and only produces an average of 5-6 pups every two years. Thus, while this species may generally be able to withstand low to moderate levels of exploitation, given the high level of fishing mortality this species has experienced and continues to experience throughout the majority of its range, its life history characteristics may only provide the species with a limited ability to compensate. Therefore, based on the best available information, these life history characteristics likely pose a risk to this species in combination with threats that reduce its abundance, such as overutilization.
Spatial Structure/Connectivity
The oceanic whitetip shark is a relatively widespread species that may be comprised of distinct stocks in the Pacific, Indian, and Atlantic oceans. The population structure and exchange between these stocks is unknown; however, based on genetic information, telemetry data, and temperature preferences it is unlikely that there is much exchange between populations in the Atlantic and Indo-Pacific Oceans
oceanic whitetip shark is a relatively widespread species that may be comprised of distinct stocks in the Pacific, Indian, and Atlantic oceans. The population structure and exchange between these stocks is unknown; however, based on genetic information, telemetry data, and temperature preferences it is unlikely that there is much exchange between populations in the Atlantic and Indo-Pacific Oceans. However, recent genetic data suggests potentially significant population structure within the Atlantic, which may be underpinned by the fact that this species exhibits a high degree of philopatry in some locations ( i.e., the species returns to the same site for purposes of breeding or feeding, etc.). While the population structure observed in the Atlantic, despite no physical or oceanographic barrier, could result in localized depletions in areas where fishing pressure is high ( e.g., Brazil), habitat characteristics that are important to this species are unknown. The species is highly mobile, and there is little known about specific migration routes. It is also unknown if there are source-sink dynamics at work that may affect population growth or species' decline. There is no information on critical source populations to suggest spatial structure and/or loss of connectivity are presently posing demographic risks to the species. Thus, based on the best available information, there is insufficient information to support the conclusion that spatial structure and connectivity currently pose a significant demographic risk to this species.
Diversity
As noted previously in the Population Structure and Genetics section, recent research suggests the oceanic whitetip shark has low genetic diversity (0.33 percent ± 0.19 percent; Ruck 2016), which is about half that of the closely related silky shark (0.61 percent ± 0.32 percent; Clarke et al., (2015a))
re and connectivity currently pose a significant demographic risk to this species.
Diversity
As noted previously in the Population Structure and Genetics section, recent research suggests the oceanic whitetip shark has low genetic diversity (0.33 percent ± 0.19 percent; Ruck 2016), which is about half that of the closely related silky shark (0.61 percent ± 0.32 percent; Clarke et al., (2015a)). The ERA team noted that the relatively low mtDNA genetic diversity of the oceanic whitetip raises potential concern for the future genetic health of this species, particularly in concert with steep global declines in abundance. Based on the fact that exploitation of the oceanic whitetip shark began with the onset of industrial fishing in the 1950s, only 5-7 generations of oceanic whitetip have passed since the beginning of this exploitation. Thus, the low genetic diversity of oceanic whitetip shark likely reflects historic levels, and the significant global declines are not yet reflected genetically (Ruck 2016). The ERA team noted that this may be a cause for concern in the foreseeable future, since a species with already relatively low genetic diversity undergoing significant levels of exploitation may increase the species' risk in terms of reduced fitness and evolutionary adaptability to a rapidly changing oceanic environment as well as potential extirpations. The ERA team also noted that low genetic diversity does not necessarily equate to a risk of extinction in and of itself for all species; but, in combination with low levels of abundance and continued exploitation, low genetic diversity may pose a viable risk to the species in the foreseeable future
olutionary adaptability to a rapidly changing oceanic environment as well as potential extirpations. The ERA team also noted that low genetic diversity does not necessarily equate to a risk of extinction in and of itself for all species; but, in combination with low levels of abundance and continued exploitation, low genetic diversity may pose a viable risk to the species in the foreseeable future.
Summary of Factors Affecting the Oceanic Whitetip Shark
As described above, section 4(a)(1) of the ESA and NMFS' implementing regulations (50 CFR 424.11(c)) state that we must determine whether a species is endangered or threatened because of any one or a combination of the following factors: The present or threatened destruction, modification, or curtailment of its habitat or range; overutilization for commercial, recreational, scientific, or educational purposes; disease or predation; the inadequacy of existing regulatory mechanisms; or other natural or manmade factors affecting its continued existence. The ERA team evaluated whether and the extent to which each of the foregoing factors contributed to the overall extinction risk of the global oceanic whitetip shark population. We summarize information regarding each of these threats below according to the factors specified in section 4(a)(1) of the ESA. Available information does not indicate that destruction, modification or curtailment of the species' habitat or range, disease or predation, or other natural or manmade factors are operative threats on this species; therefore, we do not discuss those further here. See Young et al. (2016) for
Overutilization for Commercial, Recreational, Scientific, or Educational Purposes
Threats to the oceanic whitetip shark related to overutilization stem from mortality in commercial fisheries, largely driven by demand of the international shark fin trade, bycatch-related mortality, as well as illegal, unreported, and unregulated (IUU) fishing
cuss those further here. See Young et al. (2016) for
Overutilization for Commercial, Recreational, Scientific, or Educational Purposes
Threats to the oceanic whitetip shark related to overutilization stem from mortality in commercial fisheries, largely driven by demand of the international shark fin trade, bycatch-related mortality, as well as illegal, unreported, and unregulated (IUU) fishing. The oceanic whitetip shark is generally not a targeted species, but because of its tendency to remain in the surface mixed layer of the water column (0-152 m depth) and in tropical latitudes where fishing pressure is often most concentrated for target species such as tuna, the species is frequently encountered and suffers high mortality rates in numerous fisheries throughout its global range. The oceanic whitetip shark is also considered a preferred species for the international fin trade because its large, morphologically distinct fins obtain a high value in the Asian fin market. The high value and demand for oceanic whitetip fins incentivizes the retention and subsequent finning of oceanic whitetip sharks when caught, and thus represents the main economic driver for retention and mortality of this species in commercial fisheries throughout its global range. In fact, growth in demand from the fin trade during the 1990s coincided with a pattern of soaring catches of oceanic whitetip sharks in numerous fisheries across the globe. Catches generally peaked from 1995 to 2000 and were followed by precipitous declines over the next 10 years due to severe overfishing (Hazin et al., 2007; Lawson 2011; Clarke et al., 2012; Hasarangi et al., 2012; Brodziak et al., 2013; Hall and Román 2013). The oceanic whitetip is regularly caught incidentally with PLLs, purse seines, handlines, troll and occasionally pelagic and even bottom trawls (Compagno 1984)
peaked from 1995 to 2000 and were followed by precipitous declines over the next 10 years due to severe overfishing (Hazin et al., 2007; Lawson 2011; Clarke et al., 2012; Hasarangi et al., 2012; Brodziak et al., 2013; Hall and Román 2013). The oceanic whitetip is regularly caught incidentally with PLLs, purse seines, handlines, troll and occasionally pelagic and even bottom trawls (Compagno 1984). In addition to mortality as a result of retention and finning in commercial fisheries, oceanic whitetip sharks experience varying levels of bycatch-related fishing mortality, including at-vessel and post-release mortality. Finally, recent reports of illegal trafficking of oceanic whitetip shark fins suggest the species may be heavily impacted by IUU fishing activities. Therefore, the ERA team assessed the following factors that may have contributed or continue to contribute to the historical and ongoing overutilization of the oceanic whitetip shark: Retention and finning in commercial fisheries for purposes of the international fin trade, incidental bycatch in commercial fisheries (including impacts of at-vessel and post-release mortality), and IUU fishing activities.
In the EPO, the oceanic whitetip shark is caught on a variety of gear, including longline and purse seine gear targeting tunas and swordfish. They are also believed to be taken in artisanal fisheries in many countries around the EPO (IATTC 2007). To date, the IATTC has not conducted a stock assessment for the oceanic whitetip shark. However, species-specific catch estimates based on observer data from the purse seine fishery are available from the IATTC observer database. As noted previously in the Demographic Risk Assessment—Abundance section, the oceanic whitetip was the second most abundant shark in the catches behind the silky shark, and comprised approximately 9 percent of the total shark catch from 1993-2009 (Hall and Román 2013)
pecies-specific catch estimates based on observer data from the purse seine fishery are available from the IATTC observer database. As noted previously in the Demographic Risk Assessment—Abundance section, the oceanic whitetip was the second most abundant shark in the catches behind the silky shark, and comprised approximately 9 percent of the total shark catch from 1993-2009 (Hall and Román 2013). In floating object sets, which are responsible for 90 percent of oceanic whitetip shark catches, capture probability of the species has decreased over time from a high of 30 percent capture rate per set between 1994 and 1998, to less than 5 percent from 2004 to 2008 (Morgan 2014). Estimated catches of oceanic whitetip sharks in all purse seine sets peaked with approximately 9,709 individuals caught in 1999; however, within 10 years catches dropped dramatically to an estimated 379 oceanic whitetip sharks caught in 2005. Estimated catches of oceanic whitetip shark continue to decline in the EPO tropical tuna purse seine fishery, with only 120 individuals caught in 2015. This drastic decline in oceanic whitetip catches is in stark contrast to catches of the closely related silky shark, which have remained relatively constant over the same time period. Further, size trends in this fishery show that small oceanic whitetip sharks <90 cm, which comprised 21.4 percent of the oceanic whitetips captured in 1993, have been virtually eliminated (Hall and Román 2013), indicating the possibility of recruitment failure in the population. During this same time period, there was an increase in both the total catch of tunas by purse seiners that employ drifting FADs and the number of FADs deployed (Eddy et al., 2016; Hall and Román 2016). Over the past decade, the total number of FADs deployed per year has continued to increase steadily, from about 4,000 in 2005 to almost 15,000 in 2015 (Hall and Román 2016). The total number of sets deployed has also continued increasing, with 2015 being the highest record observed
by purse seiners that employ drifting FADs and the number of FADs deployed (Eddy et al., 2016; Hall and Román 2016). Over the past decade, the total number of FADs deployed per year has continued to increase steadily, from about 4,000 in 2005 to almost 15,000 in 2015 (Hall and Román 2016). The total number of sets deployed has also continued increasing, with 2015 being the highest record observed. Thus, given the continued increase in fishing effort and expansion of the tropical tuna purse seine fleet in the Eastern Pacific, fishing pressure and associated mortality of oceanic whitetip sharks are expected to continue.
Oceanic whitetip sharks are also sometimes a significant component of the bycatch in EPO longline fisheries, and are thought to be taken by local artisanal fisheries as well. While observer data is not available from these fisheries, some limited information is available from the various countries that fish in these waters. For example, the oceanic whitetip shark was identified as one of several principal species taken by Mexican fisheries targeting pelagic sharks (Sosa-Nishizaki et al., 2008). Farther south, the oceanic whitetip shark has also been recorded in the catches of the Ecuadorian artisanal fishery. In an analysis of landings from the five principal ports of the Ecuadorian artisanal fishery from 2008-2012, 37.2 mt of oceanic whitetip shark were recorded out of a total 43,492.6 mt of shark catches (Martinez-Ortiz et al., 2015). Although limited, this information confirms that in addition to significant fishing pressure by the tropical tuna purse seine fishery, oceanic whitetip sharks are taken in longline and artisanal fisheries in unknown quantities. Based on the foregoing information, the ERA team concluded, and we agree, that overutilization of the oceanic whitetip shark is ongoing in this region, with no indication that these pressures will cease in the foreseeable future
tion to significant fishing pressure by the tropical tuna purse seine fishery, oceanic whitetip sharks are taken in longline and artisanal fisheries in unknown quantities. Based on the foregoing information, the ERA team concluded, and we agree, that overutilization of the oceanic whitetip shark is ongoing in this region, with no indication that these pressures will cease in the foreseeable future.
In the Western and Central Pacific Ocean (WCPO), the oceanic whitetip shark commonly interacts with both longline and purse seine fisheries throughout the region, with at least 20 member nations of the Western and Central Pacific Fisheries Commission (WCPFC; the RFMO responsible for the conservation and management of tuna and tuna-like species in the region) recording the species in their fisheries. As noted previously, the oceanic whitetip historically comprised between 20-28 percent of the total shark catch in some industrial longline fisheries during the 1950s and 1960s (Strasburg 1958; Taniuchi 1990). In this region, where sharks represent 25 percent of the longline fishery catch (Molony 2007), more recent observer data show that the oceanic whitetip shark represented only 6.3 percent of the total shark catch from 1991-2011(with blue shark comprising the large majority at ~80.5 percent; Lawson 2011). In the purse seine fishery, the oceanic whitetip was once the second most common species of shark caught as bycatch in the WCPO, et al., 2011a). For example, estimated catches of oceanic whitetip shark in the WCPO longline fishery suggest that catches peaked in 1998 at ~249,000 individuals and declined to only ~53,000 individuals in 2009 (Lawson 2011). It should be noted that catches by the fleets of Indonesia and the Philippines were not included because neither observer nor effort data were available for these fleets
CPO, et al., 2011a). For example, estimated catches of oceanic whitetip shark in the WCPO longline fishery suggest that catches peaked in 1998 at ~249,000 individuals and declined to only ~53,000 individuals in 2009 (Lawson 2011). It should be noted that catches by the fleets of Indonesia and the Philippines were not included because neither observer nor effort data were available for these fleets. Over the same time period (from 1995 to 2009) rates of fishing mortality consistently increased, driven mainly by the increased effort in the longline fleet, and remained substantially above the maximum sustainable yield (MSY) ( i.e., the point at which there would be an equilibrium) for the species (Rice et al., 2015). The previously discussed stock assessment report (Rice et al., 2015) attributed the greatest impact on the species to bycatch from the longline fishery, and lesser impacts from target longline activities and purse-seining (Rice and Harley 2012). In fact, Rice et al. (2015) determined that fishing mortality on oceanic whitetip sharks in the WCPO has increased to levels 6.5 times what is sustainable, thus concluding that overfishing is still occurring.
As a result of continued and increasing fishing pressure in the WCPO, size trends for oceanic whitetip have also declined, which is indicative of overutilization of the species. For example, declining median size trends were observed in all regions and sexes in both longline and purse seine fisheries until samples became too scarce for analysis. These size trends were significant for females in the longline fishery (Regions 3 and 4; See Figure 1 in Clarke et al., 2011a for the regional map), and for the purse seine fishery (Region 3). Regions 3 and 4 ( i.e., the equatorial region of the WCPO) represent the species' core habitat areas, and contain 98 percent of the operational-level reported purse seine sets and the majority of longline fishing effort (Clarke et al., 2011a; Rice et al., 2015)
longline fishery (Regions 3 and 4; See Figure 1 in Clarke et al., 2011a for the regional map), and for the purse seine fishery (Region 3). Regions 3 and 4 ( i.e., the equatorial region of the WCPO) represent the species' core habitat areas, and contain 98 percent of the operational-level reported purse seine sets and the majority of longline fishing effort (Clarke et al., 2011a; Rice et al., 2015). The decline in median size of female oceanic whitetip sharks is particularly concerning due to the potential correlation between maternal length and litter size, which has been documented in the Atlantic and Indian Oceans (Lessa et al. 1999, Bonfil et al. 2008). While Rice et al. (2015) more recently report that trends in oceanic whitetip median length are now stable, the majority of sharks observed are immature. In fact, 100 percent of oceanic whitetips sampled in the purse seine fishery have been immature since 2000 (Clarke et al., 2012).
In the U.S. Pacific, the oceanic whitetip shark is a common bycatch species in the Hawaii-based PLL fishery. This fishery began around 1917, and underwent considerable expansion in the late 1980s to become the largest fishery in the state (Boggs and Ito 1993). This fishery currently targets tunas and billfish and is managed under the auspices of the Western Pacific Fishery Management Council (WPFMC). From 1995-2006, oceanic whitetip sharks comprised approximately 3 percent of the total shark catch (Brodziak et al., 2013). Based on observer data from the Pacific Islands Regional Observer Program (PIROP), oceanic whitetip shark mean annual nominal CPUE decreased significantly from 0.428 sharks/1,000 hooks in 1995 to 0.036 sharks/1,000 hooks in 2010. This reflected a significant decrease in nominal CPUE on longline sets with positive catch from 1.690 sharks/1,000 hooks to 0.773 sharks/1,000 hooks, and a significant increase in longline sets with zero catches from 74.7 percent in 1995 to 95.3 percent in 2010
whitetip shark mean annual nominal CPUE decreased significantly from 0.428 sharks/1,000 hooks in 1995 to 0.036 sharks/1,000 hooks in 2010. This reflected a significant decrease in nominal CPUE on longline sets with positive catch from 1.690 sharks/1,000 hooks to 0.773 sharks/1,000 hooks, and a significant increase in longline sets with zero catches from 74.7 percent in 1995 to 95.3 percent in 2010. As discussed previously in the Evaluation of Demographic Risks—Abundance section, oceanic whitetip CPUE declined by more than 90 percent in the Hawaii-based PLL fishery since 1995 (Walsh and Clarke 2011; Brodziak et al., 2013). Brodziak et al. (2013) concluded that relative abundance of oceanic whitetip declined within a few years of the expansion of the longline fishery, which suggests these fisheries are contributing to the commercial overutilization of oceanic whitetip within this portion of its range. It should be noted that while the Hawaii-based PLL fishery currently catches oceanic whitetip shark as bycatch, the majority of individuals are now released alive in this fishery and the number of individuals kept has been on a declining trend. For example, according to the U.S. National Bycatch Report First Edition Update 2 (see www.st.nmfs.noaa.gov/observer-home/first-edition-update-2 ) the shallow-set fishery released alive an estimated 91-96 percent of all oceanic whitetip sharks caught from 2011 to 2013. During the same time period, the deep-set fishery released alive an estimated 78-82 percent of all oceanic whitetip sharks caught. However, it is unknown how many of these sharks survived after being released. Nonetheless, this particular fishery may be less of a threat to the oceanic whitetip shark in the foreseeable future
ed 91-96 percent of all oceanic whitetip sharks caught from 2011 to 2013. During the same time period, the deep-set fishery released alive an estimated 78-82 percent of all oceanic whitetip sharks caught. However, it is unknown how many of these sharks survived after being released. Nonetheless, this particular fishery may be less of a threat to the oceanic whitetip shark in the foreseeable future. However, across the WCPO as a whole, given the ongoing impacts to the species from significant fishing pressure (with the majority of effort concentrated in the species' core tropical habitat area), including significant declines in CPUE, biomass, and size indices, and combined with the species' relatively low-moderate productivity, it is likely that overutilization has been and continues to be an ongoing threat contributing to the extinction risk of the oceanic whitetip shark across the region.
The oceanic whitetip shark was also once described as the most common pelagic shark throughout the warm-temperate and tropical waters in the Atlantic and beyond the continental shelf in the Gulf of Mexico (Mather and Day 1954; Strasburg 1958). Oceanic whitetip sharks are taken in the Atlantic Ocean by longlines, purse seine nets, gillnets, trawls, and handlines; however, the large majority of the catch from 1990-2014 reported to ICCAT was caught by longline gear (Young et al., 2016). Oceanic whitetip sharks have exhibited a range of at-vessel mortality rates in longline gear in the Atlantic Ocean between 11-34 percent (Beerkircher et al., 2002; Coelho et al., 2012; Fernandez-Carvalho et al., 2015) and have been ranked as the 5th most vulnerable pelagic shark in an Ecological Risk Assessment that assessed 11 species of pelagic elasmobranchs (Cortes et al., 2010). In total, approximately 2,430 mt of oceanic whitetip catches were reported to ICCAT from 1990-2014; however, this is likely a severe underestimation of the total amount of oceanic whitetip sharks taken from the Atlantic
t al., 2015) and have been ranked as the 5th most vulnerable pelagic shark in an Ecological Risk Assessment that assessed 11 species of pelagic elasmobranchs (Cortes et al., 2010). In total, approximately 2,430 mt of oceanic whitetip catches were reported to ICCAT from 1990-2014; however, this is likely a severe underestimation of the total amount of oceanic whitetip sharks taken from the Atlantic. For example, Clarke (2008) calculated trade-based estimates that indicate between 80,000-210,000 oceanic whitetip sharks were sourced from the Atlantic Ocean in 2003 alone to supply the Hong Kong fin market, which translates to approximately 3,000-8,000 mt.
In the Northwest Atlantic, the oceanic whitetip is caught incidentally as bycatch by a number of fisheries, et al., 2003) and a total of 912 individuals recorded by observers in the NMFS Pelagic Observer Program from 1992-2015. Relative to target species, oceanic whitetip sharks are caught infrequently and only incidentally on PLL vessels fishing for tuna and tuna-like species. Landings and dead discards of sharks by U.S. PLL fishers in the Atlantic are monitored every year and reported to ICCAT. Overall, very few oceanic whitetip sharks were landed by the commercial fishery, except for two peaks of about 1,250 and 1,800 fish in 1983 and 1998, respectively, but otherwise total catches never exceeded 450 fish (NMFS 2009). Commercial landings of oceanic whitetip sharks in the U.S. Atlantic have been variable, but averaged approximately 1,077.4 lb (488.7 kg; 0.4887 mt) per year from 2003-2013. Although oceanic whitetip sharks have been prohibited on U.S. Atlantic commercial fishing vessels with pelagic longline gear onboard since 2011, they can still be caught as bycatch, caught with other gears, and are occasionally landed. However, since the ICCAT retention prohibition was implemented in 2011, estimated commercial landings of oceanic whitetip declined from 1.1 mt in 2011 to only 0.03 mt in 2013 (NMFS 2012; 2014)
arks have been prohibited on U.S. Atlantic commercial fishing vessels with pelagic longline gear onboard since 2011, they can still be caught as bycatch, caught with other gears, and are occasionally landed. However, since the ICCAT retention prohibition was implemented in 2011, estimated commercial landings of oceanic whitetip declined from 1.1 mt in 2011 to only 0.03 mt in 2013 (NMFS 2012; 2014). As discussed previously, the oceanic whitetip population size has likely declined significantly in this region due to historical exploitation of the species since the onset of industrial fishing (refer back to the Demographic Risk Assessment—Abundance section); however, results of the ERA team's analysis show that the oceanic whitetip shark population in this region has potentially stabilized since the 1990s/early 2000s (Young et al., 2016). The potential stabilization of oceanic whitetip sharks occurred concomitantly with the first Federal Fishery Management Plan for Sharks in the Northwest Atlantic Ocean and Gulf of Mexico, which directly manages oceanic whitetip shark under the pelagic shark group, and includes regulations on trip limits and quotas. This indicates the potential efficacy of these management measures for reducing the threat of overutilization of the oceanic whitetip shark population in this region; therefore, under current management measures, including the implementation of ICCAT Recommendation 10-07 (see Factor D—Inadequacy of Existing Regulatory Mechanisms for more details), the threat of overutilization is not likely as significant in this area relative to other portions of the species' range.
In Cuba, some evidence suggests a historical decline of oceanic whitetip shark may have occurred, although this is uncertain. In the 1960s, the oceanic whitetip shark was characterized as the most abundant species off the northwestern coast of Cuba, but since 1985, a substantial decline was observed in some species, including the oceanic whitetip
relative to other portions of the species' range.
In Cuba, some evidence suggests a historical decline of oceanic whitetip shark may have occurred, although this is uncertain. In the 1960s, the oceanic whitetip shark was characterized as the most abundant species off the northwestern coast of Cuba, but since 1985, a substantial decline was observed in some species, including the oceanic whitetip. Variations in fishing effort and changes in the fishery make it difficult to assess the present condition of the resource, but since 1981 there has been a tendency towards decline (Claro et al., 2001). Recent monitoring studies of a prominent fishing base in Cojimar, Cuba recorded the oceanic whitetip shark comprising only 2-5 percent of the shark landings from 2008-2011 (Cuba Department of Fisheries 2016). In contrast, Valdés et al., (2016) show a steady pattern of abundance for the oceanic whitetip shark in Cuban fishery landings along the northwestern coast from 2010 to 2016. However, sharks caught in Cuban fisheries are never discarded, but rather utilized for either human consumption or bait. Cuba is not a member of ICCAT, and thus ICCAT Recommendation 10-07 on the retention prohibition of oceanic whitetip sharks is not applicable in Cuban waters. Further, evidence suggests there is a prevalence of small, immature individuals in Cuban catches, which suggests the possibility of an important nursery area for this species in the region. However, because these animals are small and of less value to the fishermen, they are typically using the juvenile C. longimanus as bait while at sea, a practice which is likely in conflict with sustainable fisheries management and conservation objectives (Valedz et al., 2016) and may be contributing to overutilization of the species.
Farther south, it is likely that overutilization is an ongoing threat in the South Atlantic
are small and of less value to the fishermen, they are typically using the juvenile C. longimanus as bait while at sea, a practice which is likely in conflict with sustainable fisheries management and conservation objectives (Valedz et al., 2016) and may be contributing to overutilization of the species.
Farther south, it is likely that overutilization is an ongoing threat in the South Atlantic. Although fishing effort has been high and began intensifying in the southern Atlantic Ocean after the 1990s (Camhi et al., 2008), there is limited information on the catch rates or trends of oceanic whitetip sharks in this region. Oceanic whitetip sharks are taken as bycatch in numerous fisheries operating in the South Atlantic, including Brazilian, Uruguayan, Taiwanese, Japanese, Venezuelan, Spanish and Portuguese longline fisheries; however, the largest oceanic whitetip catching country in this region is Brazil. As noted in the Evaluation of Demographic Risks—Abundance section of this proposed rule, oceanic whitetips were historically reported as the second-most abundant shark in research surveys from northeastern Brazil between 1992 and 1997 (FAO 2012), with a high CPUE rate of 2.18 individuals per 1,000 hooks (Domingo et al., 2007). More recently, however, average CPUE in this same area has seemingly declined. It also appears that the percentage of mature sharks has declined in recent years compared to surveys conducted in the 1990s. For example, the frequency of mature sharks ≥180 cm was higher in the 1990s than in years 2005-2009. It should be noted that the data from 2005-2009 represents a much larger area of the southwestern and equatorial Atlantic and has a much larger sample size (n = 1218; Tolotti et al., 2013) than the results from the surveys conducted in the 1990s (n = 258; Lessa et al., 1999). However, the two study areas do overlap and provide some indication that the size composition of oceanic whitetip sharks in the southwestern Atlantic may be shifting downwards
esents a much larger area of the southwestern and equatorial Atlantic and has a much larger sample size (n = 1218; Tolotti et al., 2013) than the results from the surveys conducted in the 1990s (n = 258; Lessa et al., 1999). However, the two study areas do overlap and provide some indication that the size composition of oceanic whitetip sharks in the southwestern Atlantic may be shifting downwards. Catches of oceanic whitetip in the Brazilian tuna longline fishery have also shown a substantial decline, decreasing from ~640t in 2000 to only 80t in 2005 (Hazin et al., 2007). According to the ICCAT nominal catch database, catches of oceanic whitetip shark by Brazilian vessels continued to decline, with 0 mt reported from 2009-2012 and only 12 mt from 2013-2014. Although robust standardized CPUE data are not available for the species, making it difficult to evaluate whether the decline in catches resulted from decreased abundance or from changes in catchability, related, for instance, to targeting strategies (Hazin et al., 2007), a recent tagging study indicates that the preferred horizontal and vertical habitat of oceanic whitetip shark, including potential nursery areas, is heavily impacted by the industrial longline fishery. Telemetry data provides evidence that the equatorial region off Northeast Brazil is an area where the oceanic whitetip shark shows a high degree of philopatry ( i.e., site fidelity). This same area also happens to be where the highest level of fishing effort is concentrated. For example, from 1999-2011, despite a wide distribution i.e., the equatorial region of Northeast Brazil). Thus, the majority of fishing effort by the Brazilian fleet directly overlaps the preferred habitat area of oceanic whitetip sharks (Tolotti et al., 2015a). Further, many studies show a substantially high percentage of juveniles in the catches from this region (Coelho et al., 2009; Tambourgi et al., 2013; Tolotti et al., 2013; Frédou et al., 2015), which suggests the presence of nursery habitat
). Thus, the majority of fishing effort by the Brazilian fleet directly overlaps the preferred habitat area of oceanic whitetip sharks (Tolotti et al., 2015a). Further, many studies show a substantially high percentage of juveniles in the catches from this region (Coelho et al., 2009; Tambourgi et al., 2013; Tolotti et al., 2013; Frédou et al., 2015), which suggests the presence of nursery habitat. For example, Tambourgi et al. (2013) found that 80.5 percent of females were immature and 72.4 percent of males were immature in the Brazilian pelagic longline fishery between December 2003 and December 2010. Thus, it is likely that the intensive fishing pressure of oceanic whitetip across its preferred vertical and horizontal habitat, including nursery areas in Brazilian waters, is negatively impacting oceanic whitetip sharks at all life stages, and contributing to the overutilization of the species. In addition to information from Brazil, a recent study that synthesized information on shark catch rates for the major shark species caught by multiple fleets in the South Atlantic from 1979 and 2011 ( e.g., Belize, Bolivia, Brazil, Canada, Spain, Guyana, Honduras, Iceland, Japan, Saint Kitts and Nevis, Korea, Morocco, Panama, Portugal, Taiwan, United Kingdom, Uruguay, United States, Saint Vincent and the Grenadines, and Vanuatu) concluded that declines of many shark species, including the oceanic whitetip, coincided with significant fishing effort expansion, a lack of regulatory measures to deal with shark bycatch, finning and directed fishing for sharks by some fleets (Barreto et al., 2015). Based on the foregoing information, the ERA team concluded, and we agree, that overutilization in the South Atlantic Ocean is likely a threat contributing to the oceanic whitetip's risk of extinction in the foreseeable future.
Overutilization is also likely a threat to oceanic whitetip sharks in the Indian Ocean
atch, finning and directed fishing for sharks by some fleets (Barreto et al., 2015). Based on the foregoing information, the ERA team concluded, and we agree, that overutilization in the South Atlantic Ocean is likely a threat contributing to the oceanic whitetip's risk of extinction in the foreseeable future.
Overutilization is also likely a threat to oceanic whitetip sharks in the Indian Ocean. The oceanic whitetip is reported as bycatch in all three major fisheries operating in the Indian Ocean; the species is considered “frequent” in both longline and purse seine fisheries, and “very frequent” in the gillnet fishery (Murua et al., 2013b), with gillnet fisheries reporting the highest nominal catches of sharks in 2014, and making up nearly 40 percent of total catches (Ardill et al., 2011; IOTC 2015a). Although information from this r

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Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2016-31460. Check the current official text before relying on it. Not legal advice.