Endangered and Threatened Wildlife; 90-Day Finding on Petitions To List the Dusky Shark as Threatened or Endangered Under the Endangered Species Act
Federal Register, Volume 78 Issue 96 (Friday, May 17, 2013)
Federal Register Volume 78, Number 96 (Friday, May 17, 2013)
Proposed Rules
Pages 29100-29110
From the Federal Register Online via the Government Printing Office www.gpo.gov
FR Doc No: 2013-11862
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DEPARTMENT OF COMMERCE
National Ocean and Atmospheric Administration
50 CFR Parts 223 and 224
Docket No. 130214141-3141-01
RIN 0648-XC515
Endangered and Threatened Wildlife; 90-Day Finding on Petitions To List the Dusky Shark as Threatened or Endangered Under the Endangered Species Act
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.
ACTION: 90-day petition finding, request for information, and initiation of status review.
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SUMMARY: We, NMFS, announce a 90-day finding on petitions to list the dusky shark (Carcharhinus obscurus) range-wide or, in the alternative, the Northwest Atlantic and Gulf of Mexico population of the dusky shark as a threatened or endangered distinct population segment (DPS) under the Endangered Species Act (ESA), and to designate critical habitat concurrently with the listing. We find that the petitions present substantial scientific or commercial information indicating that the petitioned action may be warranted for the Northwest Atlantic and Gulf of Mexico population of dusky shark; we find that the petitions fail to present substantial scientific or commercial information indicating that the petitioned action may be warranted for the dusky shark range-
wide. Therefore, we will conduct a status review of the Northwest Atlantic and Gulf of Mexico population of dusky shark to determine if the petitioned action is warranted. To ensure that the status review is comprehensive, we are soliciting scientific and commercial information pertaining to this petitioned species from any interested party.
DATES: Information and comments on the subject action must be received by July 16, 2013.
ADDRESSES: You may submit comments, information, or data on this document, identified by the code NOAA-NMFS-2013-0045, by any of the following methods:
Electronic Submissions: Submit all electronic comments via the Federal eRulemaking Portal. Go to www.regulations.gov/#!docketDetail;D=NOAA-NMFS-2013-0045, click the ``Comment Now!'' icon,
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complete the required fields, and enter or attach your comments.
Mail: Submit written comments to Office of Protected Resources, NMFS, 1315 East-West Highway, Silver Spring, MD 20910.
Fax: 301-713-4060, Attn: Maggie Miller.
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), although submitting comments anonymously will prevent NMFS from contacting you if NMFS has difficulty retrieving your submission. Attachments to electronic comments will be accepted in Microsoft Word, Excel, or Adobe PDF file formats only.
FOR FURTHER INFORMATION CONTACT: Maggie Miller, NMFS, Office of Protected Resources, (301) 427-8403.
SUPPLEMENTARY INFORMATION:
Background
On November 14, 2012, we received a petition from WildEarth Guardians (WEG) to list the dusky shark (Carcharhinus obscurus) as threatened or endangered under the ESA throughout its entire range, or, as an alternative, to list the Northwest Atlantic/Gulf of Mexico DPS as threatened or endangered. The petitioners also requested that critical habitat be designated for the dusky shark under the ESA. On February 1, 2013, we received a petition from Natural Resources Defense Council (NRDC) to list the northwest Atlantic DPS of dusky shark as threatened, or, as an alternative, to list the dusky shark range-wide as threatened, and a request that critical habitat be designated. The joint USFWS/NMFS petition management handbook states that if we receive two equivalent petitions for the same species and a 90-day finding has not yet been made on the earlier petition, then the later petition will be combined with the earlier petition and a combined 90-day finding will be prepared. Given that, this 90-day finding will address both the WEG and NRDC petitions for dusky shark. Copies of the petitions are available upon request (see ADDRESSES, above).
ESA Statutory, Regulatory, and Policy Provisions and Evaluation Framework
Section 4(b)(3)(A) of the ESA of 1973, as amended (16 U.S.C. 1531 et seq.), requires, to the maximum extent practicable, that within 90 days of receipt of a petition to list a species as threatened or endangered, the Secretary of Commerce make a finding on whether that petition presents substantial scientific or commercial information indicating that the petitioned action may be warranted, and to promptly publish such finding in the Federal Register (16 U.S.C. 1533(b)(3)(A)). When it is found that substantial scientific or commercial information in a petition indicates the petitioned action may be warranted (a ``positive 90-day finding''), we are required to promptly commence a review of the status of the species concerned, during which we will conduct a comprehensive review of the best available scientific and commercial information. In such cases, we conclude the review with a finding as to whether, in fact, the petitioned action is warranted within 12 months of receipt of the petition. Because the finding at the 12-month stage is based on a more thorough review of the available information, as compared to the narrow scope of review at the 90-day stage, a ``may be warranted'' finding does not prejudge the outcome of the status review.
Under the ESA, a listing determination may address a species, which is defined to also include subspecies and, for any vertebrate species, any DPS that interbreeds when mature (16 U.S.C. 1532(16)). A joint NMFS-U.S. Fish and Wildlife Service (USFWS) (jointly, ``the Services'') policy clarifies the agencies' interpretation of the phrase ``distinct population segment'' for the purposes of listing, delisting, and reclassifying a vertebrate species under the ESA (61 FR 4722; February 7, 1996) (``DPS Policy''). A species is ``endangered'' if it is in danger of extinction throughout all or a significant portion of its range, and ``threatened'' if it is likely to become endangered within the foreseeable future throughout all or a significant portion of its range (ESA sections 3(6) and 3(20), respectively, 16 U.S.C. 1532(6) and (20)). Pursuant to the ESA and our implementing regulations, we determine whether species are threatened or endangered based on any one or a combination of the following five section 4(a)(1) factors: (1) The present or threatened destruction, modification, or curtailment of habitat or range; (2) overutilization for commercial, recreational, scientific, or educational purposes; (3) disease or predation; (4) inadequacy of existing regulatory mechanisms; and (5) any other natural or manmade factors affecting the species' existence (16 U.S.C. 1533(a)(1), 50 CFR 424.11(c)). In evaluating whether a population constitutes a significant portion of the species' range, we consider the portion of the range to be significant if its contribution to the overall viability of the species is so important that, without it, the species may be in danger of extinction. These considerations are consistent with interpretations and principles in the NMFS and USFWS Draft Policy on Interpretation of the Phrase ``Significant Portion of Its Range'' in the Endangered Species Act's Definitions of ``Endangered Species'' and ``Threatened Species,'' which we consider as nonbinding guidance in making listing determinations until a final policy is published. In the draft policy, the Services explain that this definition of ``significant'' for the purpose of analyzing whether a population constitutes a significant portion of a species range differs from the definition of ``significant'' defined in the Services' DPS Policy and used for DPS analysis (76 FR 76987; December 9, 2011).
ESA-implementing regulations issued jointly by NMFS and USFWS (50 CFR 424.14(b)) define ``substantial information'' in the context of reviewing a petition to list, delist, or reclassify a species as the amount of information that would lead a reasonable person to believe that the measure proposed in the petition may be warranted. In evaluating whether substantial information is contained in a petition, the Secretary must consider whether the petition: (1) Clearly indicates the administrative measure recommended and gives the scientific and any common name of the species involved; (2) contains detailed narrative justification for the recommended measure, describing, based on available information, past and present numbers and distribution of the species involved and any threats faced by the species; (3) provides information regarding the status of the species over all or a significant portion of its range; and (4) is accompanied by the appropriate supporting documentation in the form of bibliographic references, reprints of pertinent publications, copies of reports or letters from authorities, and maps (50 CFR 424.14(b)(2)).
Judicial decisions have clarified the appropriate scope and limitations of the Services' review of petitions at the 90-
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day finding stage, in making a determination that a petitioned action ``may be'' warranted. As a general matter, these decisions hold that a petition need not establish a ``strong likelihood'' or a ``high probability'' that a species is either threatened or endangered to support a positive 90-day finding.
We evaluate the petitioners' request based upon the information in the petition including its references and the information readily available in our files. We do not conduct additional research, and we do not solicit information from parties outside the agency to help us in evaluating the petition. We will accept the petitioners' sources and characterizations of the information presented if they appear to be based on accepted scientific principles, unless we have specific information that indicates that the petition's information is incorrect, unreliable, obsolete, or otherwise irrelevant to the requested action. Information that is susceptible to more than one interpretation or that is contradicted by other available information will not be dismissed at the 90-day finding stage, so long as it is reliable and a reasonable person would conclude that it supports the petitioners' assertions. In other words, conclusive information indicating that the species may meet the ESA's requirements for listing is not required to make a positive 90-day finding. We will not conclude that a lack of specific information alone negates a positive 90-day finding if a reasonable person would conclude that the unknown information itself suggests an extinction risk of concern for the species at issue.
To make a 90-day finding on a petition to list a species, we evaluate whether the petition presents substantial scientific or commercial information indicating that the subject species may be either threatened or endangered, as defined by the ESA. First, if the petition requests listing of a subspecies or a DPS, we evaluate whether the information presented in the petition, along with the information readily available in our files, indicates that the petitioned entity constitutes a ``species'' eligible for listing under the ESA, pursuant to the DPS Policy. Next, we evaluate whether the information indicates that the species faces an extinction risk that is cause for concern throughout all or a significant portion of its range; this may be indicated in information expressly discussing the species' status and trends, or in information describing impacts and threats to the species. We evaluate any information on specific demographic factors pertinent to evaluating extinction risk for the species (e.g., population abundance and trends, productivity, spatial structure, age structure, sex ratio, diversity, current and historical range, habitat integrity or fragmentation), and the potential contribution of identified demographic risks to extinction risk for the species. We then evaluate the potential links between these demographic risks and the causative impacts and threats identified in section 4(a)(1). Information presented on impacts or threats should be specific to the species and should reasonably suggest that one or more of these factors may be operative threats that act or have acted on the species to the point that it may warrant protection under the ESA. Broad statements about generalized threats to the species, or identification of factors that could negatively impact a species, do not constitute substantial information indicating that listing may be warranted. We look for information indicating that not only is the particular species exposed to a factor, but that the species may be responding in a negative fashion; then we assess the potential significance of that negative response.
Many petitions identify risk classifications made by non-
governmental organizations, such as the International Union on the Conservation of Nature (IUCN), the American Fisheries Society, or NatureServe, as evidence of extinction risk for a species. Risk classifications by other organizations or made under other Federal or state statutes may be informative, but the classification alone may not provide the rationale for a positive 90-day finding under the ESA. For example, as explained by NatureServe, their assessments of a species' conservation status do ``not constitute a recommendation by NatureServe for listing under the U.S. Endangered Species Act'' because NatureServe assessments ``have different criteria, evidence requirements, purposes and taxonomic coverage than government lists of endangered and threatened species, and therefore these two types of lists should not be expected to coincide'' (http://www.natureserve.org/prodServices/statusAssessment.jsp). Thus, when a petition cites such classifications, we will evaluate the source of information that the classification is based upon in light of the standards on extinction risk and impacts or threats discussed above.
Distribution and Life History of the Dusky Shark
The dusky shark is part of the Carcharhinidae family. It is a coastal-pelagic species that inhabits warm temperate and tropical waters (FAO, 2012). It has a global but patchy distribution, with its range-wide occurrence poorly known. In the Northwest Atlantic, dusky sharks can be found from southern Massachusetts and Georges Bank to Florida, the Bahamas, Cuba, and the northern Gulf of Mexico (NMFS, 2011a). Dusky shark distribution off Central America is not well known (NMFS, 2011a). In the Eastern Pacific, the species is thought to occur off the coast of southern California to the Gulf of California, Revillagigedo Islands, and possibly Chile (NOAA, 1998; Musick et al., 2007). The species can also be found off the coasts of Australia, Nicaragua, and southern Brazil (NMFS, 2011a). According to Dudley et al. (2005), the shark's distribution in the western Indian Ocean extends from the Red Sea to the southern tip of Africa and off the coast of Madagascar. The species is also thought to be found in the Mediterranean Sea, and off the coasts and continental shelves of Japan, China, Vietnam, New Caledonia, and North Africa, possibly around oceanic islands off western Africa (Musick et al., 2007; NMFS, 2011a).
The dusky shark is a highly migratory species that occurs in both inshore (surf zone) and offshore waters, from the surface to depths as deep as 1,883 feet (574 m) (NOAA, 1998; Hoffmayer et al., 2010; NMFS, 2011a). The shark avoids areas of lower salinity and is rarely found in estuarine environments (NOAA, 1998; SEDAR, 2011). Along the U.S. coasts, the dusky shark undertakes long temperature-related migrations, moving north in the summer as waters warm and retreating south in the fall as water temperatures drop (NMFS, 2011a). Seasonal migrations have also been documented off South Africa (NOAA, 1998). In western Australia, both adolescents and adults move inshore during the summer and fall, with neonates occupying separate inshore areas (NOAA, 1998).
The general life history pattern of the dusky shark is that of a long lived (oldest known female shark aged at 39 years), slow growing, and late maturing species (SEDAR, 2011). The dusky shark is a large, fairly slender shark, with an average total length (TL) of around 11.8 feet (360 cm) and weight of 400 pounds (180 kg) (NMFS, 2011a). Northwest Atlantic and Gulf of Mexico dusky males attain sexual maturity at around 280 cm TL, or 19 years, and females reach sexual maturity at 284 cm TL, or 21 years (NOAA, 1998; NMFS, 2011a). Similar maturity sizes have been observed for dusky sharks from South
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Africa and Australia (NOAA, 1998). The dusky shark is viviparous (i.e., gives birth to live young), with a gestation period of around 18 months and a triennial reproductive cycle (SEDAR, 2011). Litter sizes range between 3 and 14 pups (NMFS, 2011a; SEDAR, 2011) with the pupping months for the Northwest Atlantic and Gulf of Mexico dusky population occurring from May to June. Young are born at sizes of 33 to 39 inches (85--100 cm) (NMFS, 2011a).
The shark has a rounded snout that is shorter than or equal to the width of its mouth and a low ridge along its back between its dorsal fins (NMFS, 2011a). The dorsal fin originates over or near the free rear tips of moderately large pectoral fins, and the second dorsal fin has a free tip length that is usually not more than twice its fin height (NMFS, 2011a; FLMNH, undated). The dusky shark is colored bronzy gray to blue gray above and white ventrally, and is also known as the bronze whaler or black whaler (NMFS, 2011a). It is a high trophic level predator (Corteacutes, 1999) with a diet that includes a wide variety of bony and cartilaginous fishes and squid (NOAA, 1998). In the Indian Ocean, young dusky sharks have been observed feeding in large aggregations (NOAA, 1998).
With respect to ESA listing actions, we added the dusky shark to our candidate species list in 1997 (62 FR 37560; July 14, 1997), but subsequently transferred the Northwest Atlantic and Gulf of Mexico population to our Species of Concern List in 2004 (69 FR 19975; April 15, 2004). There is no mandatory Federal protection for candidate species or species of concern, but voluntary protection is urged.
Analysis of Petition and Information Readily Available in NMFS Files
We evaluated the information provided in the petitions and readily available in our files to determine if the petitions presented substantial scientific or commercial information indicating that the petitioned actions may be warranted. The petitions contain information on the species, including the taxonomy, species description, geographic distribution, habitat, some population status and trends, and factors contributing to the species' decline. According to the WEG petition, at least four of the five causal factors in section 4(a)(1) of the ESA are adversely affecting the continued existence of the dusky shark, specifically: (A) Present and threatened destruction, modification, and curtailment of habitat and range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (D) inadequacy of existing regulatory mechanisms; and (E) other natural or manmade factors affecting its continued existence. The focus of the NRDC petition is mainly on the northwest Atlantic population and identified the threats of: (B) overutilization for commercial, recreational, scientific, or educational purposes; (D) inadequacy of existing regulatory mechanisms; and (E) other natural or manmade factors affecting its continued existence. In the following sections, we use the information presented in the petitions and in our files to determine whether the petitioned action may be warranted. We consider both the information presented for the global population of dusky sharks (as provided primarily in the WEG petition) as well as the information presented for the Northwest Atlantic and Gulf of Mexico population (provided in both petitions) on the specific ESA section 4(a)(1) factors affecting the species' risk of extinction. We provide separate analyses and conclusions regarding the information presented by the petitioners and in our files for the global and for the Northwest Atlantic and Gulf of Mexico populations since we were petitioned to list either the global population (range-wide) or the Northwest Atlantic and Gulf of Mexico population.
Qualification of Northwest Atlantic and Gulf of Mexico Population as a DPS
Both petitions assert that the Northwest Atlantic and Gulf of Mexico population (henceforth referred to as ``NW Atlantic population'') of dusky shark qualifies as a DPS because it is both a discrete and significant population segment of the species as defined in the DPS Policy. The NRDC petition states that the NW Atlantic population is discrete based on both genetic and spatial separation from other populations of dusky sharks. Genetic analyses indicate that the NW Atlantic population of dusky sharks is genetically differentiated from other populations of dusky sharks (Benavides et al., 2011; Gray et al., 2012). Results from both nuclear microsatellite DNA and mitochondrial control region analyses showed significant genetic differentiation between the western North Atlantic, South African, and Australian dusky shark populations, with a low frequency of migration between these populations (Benavides et al., 2011; Gray et al., 2012). Analysis of mitochondrial control regions also indicate that dusky sharks off the U.S. East Coast and in the Gulf of Mexico are not genetically distinct (Benavides et al., 2011), with tagging data that show a high frequency of movements between these two basins (SEDAR, 2011). Furthermore, Benavides et al. (2011) provides preliminary evidence of population structure between the NW Atlantic population and the dusky sharks in the Southwest Atlantic (off Brazil), suggesting that the NW Atlantic population, if it were depleted, would not likely be replenished by immigrant females from the Southwest Atlantic population.
In addition to genetic separation, the NRDC contends that the NW Atlantic population is geographically separated from other populations. NRDC indicates that the NW Atlantic population primarily inhabits U.S. waters, and as such is delimited by international governmental boundaries within which differences in control of exploitation, management of habitat, conservation status, or regulatory mechanisms exist that are significant in light of section 4(a)(1)(D) of the ESA.
Both petitions make the case that the NW Atlantic population is significant to the taxon. As described above, the NW Atlantic population appears to be genetically distinct and geographically separate from other dusky shark populations, with evidence of little mixing between neighboring populations (Benavides et al., 2011; Gray et al., 2012). Thus, the petitions reason that loss of this population would result in a significant gap in the range of the species because it is unlikely to be repopulated by sharks from other populations.
Overall, based on the above analysis, we conclude that the information in the two petitions and in our files suggests that the NW Atlantic population of dusky shark may qualify as a DPS under the discreteness and significance criteria of the DPS Policy. We will explore this designation further and conduct a formal DPS analysis during the status review.
Qualification of the Northwest Atlantic and Gulf of Mexico as a Significant Portion of the Range (SPOIR)
The NRDC petition specifically requests that we list the dusky shark as threatened because the species is likely to become endangered in a significant portion of its range (specifically throughout the habitat of the Northwest Atlantic, including the Gulf of Mexico). The WEG petition makes a similar statement: ``The Gulf of Mexico comprises a significant portion of the dusky shark's range'' and focuses part of its threats analysis on this portion. However, we conclude that neither petition presented substantial information, nor is there information in our files, to indicate that the Northwest
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Atlantic and Gulf of Mexico is a significant portion of the dusky shark's range. In making this assessment we considered a portion of the range to be significant if its contribution to the overall viability of the dusky shark was so important that, without it, the dusky shark would be in danger of extinction. These considerations are consistent with interpretations and principles in the NMFS and USFWS Draft Policy on Interpretation of the Phrase ``Significant Portion of Its Range'' in the Endangered Species Act's Definitions of ``Endangered Species'' and ``Threatened Species,'' which we consider as nonbinding guidance in making listing determinations until a final policy is published (76 FR 76987; December 9, 2011).
As requested by the NRDC, we considered whether the loss of the northwest Atlantic portion would be expected to increase the entire species' vulnerability to extinction to the point where the global population of dusky sharks would be in danger of extinction. However, neither petition provides substantial evidence that the global population may be at risk of extinction from the loss of the Northwest Atlantic portion, nor do we have information that would support this in our files. The WEG petition presents information on threats to the global population, whereas the NRDC petition does not; however, neither petition presents information about the dependence of the global population on the Northwest Atlantic portion for survival. Therefore, we conclude that the petitions do not provide substantial evidence that the Northwest Atlantic may qualify as a significant portion of the dusky shark's range or that listing of the global population of shark may be warranted because the population is threatened or endangered in a significant portion of its range.
Our analysis below considers the application of the ESA section 4(a)(1) factors to the Northwest Atlantic population in determining whether the WEG and NRDC petitions present substantial information indicating that listing the Northwest Atlantic population may be warranted. In addition, we consider the application of the ESA section 4(a)(1) factors to the global population in determining whether the WEG petition presents substantial information indicating that listing the global population may be warranted.
Factor A: Present and Threatened Destruction, Modification, or Curtailment of Habitat or Range
NW Atlantic Population Analysis
The WEG petition identifies the 2010 Deepwater Horizon oil spill as an event that has degraded the marine environment used by the NW Atlantic population of dusky sharks, but does not provide any information on how the effects of the spill contribute to the extinction risk of the species. It cites a National Geographic Daily News article (Handwerk, 2010) that discusses the potential negative impacts of the spill on whale sharks, a large, filter-feeding species. When feeding, the whale shark swims with its mouth open, filtering over 100,000 gallons of water an hour, capturing prey and passing the water through its gills (Handwerk, 2010). Due to this type of feeding behavior, scientists believe that the oil from the spill may have had lethal impacts to the whale sharks (Handwerk, 2010). Specifically, the article mentions sightings of whale sharks that were unable to avoid the oil slick, and suggests that the oil may have clogged the sharks' gills, suffocating them, or contaminated their prey; however, there have been no reports of dead whale sharks (Handwerk, 2010). The article does not mention the dusky shark or its exposure to the oil. The dusky shark is not a filter-feeder, and thus the effects of the oil spill on the whale shark do not provide information on the effects of the spill on the dusky shark. In addition, the WEG petition does not provide any information on how the oil has affected the dusky sharks' extinction risk, but mentions that researchers are currently studying the fatal and non-fatal impacts of the oil spill on the species. The petition does note that apex predators can bioaccumulate toxic chemicals that they ingest from their prey, but does not provide information on the amount of toxic substances from prey that the global population or the NW Atlantic population is absorbing, or how much this threat is a cause for concern in relation to extinction risk.
The WEG petition notes that the oil ``has degraded sea grass habitat south of Chandeleur Island a known nursery for a number of shark species'' but does not identify if this location is a known nursery ground for the dusky shark. Neither the reference (CBD, undated) nor information in our files (NMFS, 2009) indicates that this is a nursery area for dusky sharks.
Global Population Analysis
In terms of other threats to the habitat of the global population of dusky sharks, the WEG petition cites a general statement about the rate of development in the United States and abroad, and the resultant destructive impact on coastal habitat (Camhi et al., 1998), but does not provide any details on how this development is destroying specific dusky shark habitat or contributing to its extinction risk. Broad statements about generalized threats to the species do not constitute substantial information indicating that listing under the ESA may be warranted.
Factor A Conclusion
We conclude that the information presented in the WEG petition on threats from the modification of habitat does not provide substantial information indicating that listing is warranted for the global population or NW Atlantic population. However, we acknowledge that although there is no specific information at this time on the effects of the oil spill on the NW Atlantic population, the petition did reference a study (Hueter and Gelsleichter, 2010) that is currently looking at the sub-lethal impacts of oil exposure, with dusky sharks listed as a target species. We may re-examine this factor as new information becomes available. The NRDC petition did not identify habitat modification or destruction as a threat to the NW Atlantic population.
Factor B: Overutilization for Commercial, Recreational, Scientific, or Educational Purposes
NW Atlantic Population Analysis
The WEG petition presents information on threats from commercial and recreational overexploitation for the global population and the NW Atlantic population separately. However, in discussing the ``domestic'' commercial and recreational exploitation of the global population, the petition focuses entirely on information concerning the NW Atlantic population. In this section, the petition states ``The dusky shark is subject to overfishing domestically . . . throughout its range, including in the NWA/GOM NW Atlantic and Pacific'' and references the latest Southeast Data, Assessment, and Review (SEDAR) stock assessment report for the dusky shark (henceforth referred to as ``SEDAR 21'') (SEDAR, 2011). However, this statement is incorrect, as SEDAR 21 did not examine the status of the entire dusky shark population or the Pacific population of dusky sharks, only the Northwest Atlantic and Gulf of Mexico stock.
Information from the petitions suggests that the primary threat to the
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NW Atlantic population is from fishing pressure by commercial and recreational fisheries. Dusky sharks off the U.S. East Coast have been a prohibited species in U.S. Atlantic Highly Migratory Species (HMS) fisheries since 2000 (NMFS, 1999), meaning that neither U.S. commercial nor recreational fishers are allowed to legally land this species. However, according to the results from SEDAR 21, the stock is still overfished with overfishing occurring. This suggests that the species continues to be caught as bycatch in pelagic and bottom longline fisheries and/or is misidentified by recreational and commercial fishers and seafood dealers, with other sharks recorded as dusky shark in landings, log books and dealer reports (Corteacutes et al., 2006; NMFS, 2012a). Historically, the fishing mortality of this population was estimated to be low from 1960 through the early 1980s, but was thought to have increased to unsustainably high levels in the 1990s, before declining following the prohibition of dusky landings in 2000 (SEDAR, 2011). In the 2006 stock assessment for the Northwest Atlantic and Gulf of Mexico dusky shark population, it was estimated that the stock (in 2004) had suffered significant declines from its virgin population size (in 1960) (Corteacutes et al., 2006). Three forms of Bayesian surplus production models predicted depletions of over 80 percent, an age-structured production model estimated a decline of 62-
80 percent, and a catch-free age-structure production model estimated a decrease in the spawning stock biomass (SSB) of 92-93 percent (Corteacutes et al., 2006; SEDAR, 2011). The stock assessment also found statistically significant decreasing trends in the average weight of the catch, suggesting that the majority of dusky sharks being caught were immature and that the stock was heavily exploited (Corteacutes et al., 2006). Given the historically heavy fishing on this population, and its low productivity and hence high vulnerability to exploitation, the stock assessment projected that the Northwest Atlantic and Gulf of Mexico population required 100 to 400 years to rebuild (Corteacutes et al., 2006; SEDAR, 2011). Based on these results, NMFS declared the dusky shark stock in the Northwest Atlantic and Gulf of Mexico to be overfished with overfishing occurring (71 FR 65087; November 7, 2006) and established a rebuilding plan in July 2008. In 2011, the status of the Northwest Atlantic and Gulf of Mexico stock was re-evaluated through the SEDAR process (76 FR 62331; October 7, 2011), with results that indicate this dusky shark population is still overfished and continues to experience overfishing, even though harvest of the species is prohibited (SEDAR, 2011).
The NRDC petition contends that although SEDAR 21 determined that the stock is experiencing overfishing, the current fishing mortality (F) values calculated by SEDAR 21 are underestimations and therefore ``the percent reduction needed to end overfishing (a 36 percent reduction) as well as rebuild the fishery (62 percent) are underestimated.'' SEDAR 21 selected a range of 44.2--65 percent as the discard mortality for dusky sharks caught by bottom longline (BLL) gear (SEDAR, 2011). The petition states that these estimates ``represent average values across age classes and are substantially lower than capture mortality rates of juvenile dusky sharks, a major source of bycatch'' and references Morgan and Burgess (2007) and Romine et al. (2009). These two papers present at-vessel mortality rates for different age groups of dusky sharks on BLL gear. Morgan and Burgess (2007) estimated an 87.7 percent mortality rate for young dusky sharks (0-100 cm fork length, FL) and an 82.4 percent mortality rate for juveniles (101-231 cm FL). Romine et al. (2009) estimated mortality rates that ranged between 69 and 79 percent for dusky sharks
