Endangered and Threatened Wildlife and Plants; Notice of 12-Month Finding on a Petition To List Thorny Skate as Threatened or Endangered Under the Endangered Species Act (ESA)
We, NMFS, have completed a comprehensive status review under the Endangered Species Act (ESA) for thorny skate (Amblyraja radiata) in response to a petition to list this species. Based on the best scientific and commercial information available, including the status review report, and taking into account ongoing efforts to protect this species, we have determined that the listing of a Northwest Atlantic (NWA) distinct population segment (DPS) or a U.S. DPS is not warranted at this time. While the petition only sought the listing of one of two alternative DPSs, we exercised our discretion to consider whether the listing of the species at the taxonomic level is warranted. We conclude that thorny skate is not currently in danger of extinction throughout all or a significant portion of its range or likely to become so in the foreseeable future.
Federal Register, Volume 82 Issue 36 (Friday, February 24, 2017)
Federal Register Volume 82, Number 36 (Friday, February 24, 2017)
From the Federal Register Online via the Government Publishing Office www.gpo.gov
FR Doc No: 2017-03644
DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
Docket No. 150901797-7177-02
Endangered and Threatened Wildlife and Plants; Notice of 12-Month Finding on a Petition To List Thorny Skate as Threatened or Endangered Under the Endangered Species Act (ESA)
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; 12-month finding and availability of status review document.
SUMMARY: We, NMFS, have completed a comprehensive status review under the Endangered Species Act (ESA) for thorny skate (Amblyraja radiata) in response to a petition to list this species. Based on the best scientific and commercial information available, including the status review report, and taking into account ongoing efforts to protect this species, we have determined that the listing of a Northwest Atlantic (NWA) distinct population segment (DPS) or a U.S. DPS is not warranted at this time. While the petition only sought the listing of one of two alternative DPSs, we exercised our discretion to consider whether the listing of the species at the taxonomic level is warranted. We conclude that thorny skate is not currently in danger of extinction throughout all or a significant portion of its range or likely to become so in the foreseeable future.
DATES: This finding was made on February 24, 2017.
ADDRESSES: The status review document for thorny skate is available electronically at: www.nmfs.noaa.gov/pr/species/notwarranted.htm. You may also obtain a copy by submitting a request to the Protected Resources Division, NMFS GARFO, 55 Great Republic Drive, Gloucester, MA 01930, Attention: Thorny Skate 12-month Finding.
FOR FURTHER INFORMATION CONTACT: Kim Damon-Randall, NMFS Greater Atlantic Regional Fisheries Office, 978-282-8485; or Marta Nammack, NMFS Office of Protected Resources, 301-427-8469.
We received a petition, dated May 28, 2015, from Animal Welfare Institute (AWI) and Defenders of Wildlife (DW) requesting that we list a ``Northwest Atlantic DPS'' of thorny skate as threatened or endangered under the ESA, or, as an alternative, a ``U.S. DPS'' as threatened or endangered. The petition also requests we designate critical habitat for thorny skate. In response to this petition, we published a ``positive'' 90-finding on October 26, 2015 (80 FR 65175), in which we concluded that the petition presented substantial scientific and commercial information indicating that listing under the ESA may be warranted, and a review of the status of the species was initiated.
We then performed a detailed review and determined that the best available scientific and commercial information does not support a listing. The resulting status review report included an in-depth review of the available scientific literature, an analysis of the five ESA section 4(a)(1) factors (16 U.S.C. 1533(a)(1)(A)-(E)), and an assessment of extinction risk. The status review report was independently peer reviewed by external experts. This listing determination is based on the status
review report, along with other published and unpublished information.
Listing Species Under the ESA
We are responsible for determining whether the thorny skate is 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). Under the joint DPS policy, we consider the following 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 species or subspecies to which it belongs.
Section 3 of the ESA further 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, we interpret an ``endangered species'' to be one that is presently in danger of extinction. A ``threatened species,'' on the other hand, is not presently in danger of extinction, but is likely to become so in the foreseeable future (that is, at a later time). In other words, the primary statutory difference between a threatened and endangered species is the timing of when a species may be in danger of extinction, either presently (endangered) or in the foreseeable future (threatened). Section 4(a)(1) of the ESA 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 predation; the inadequacy of existing regulatory mechanisms; or other natural or manmade factors affecting its continued existence. (16 U.S.C. 1533(a)(1)(A)-(E)). Section 4(b)(1)(A) of the ESA requires us to make listing determinations based solely on the best scientific and commercial data available after conducting a review of the status of the species and after taking into account efforts being made by any state or foreign nation or political subdivision thereof to protect the species. In evaluating the efficacy of existing domestic protective efforts, we rely on the Services' joint 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 not yet demonstrated effectiveness.
The status review report for thorny skate is composed of two components: (1) A scientific literature review and analysis of the five ESA section 4(a)(1) factors and (2) an assessment of the extinction risk. A biologist in NMFS' Greater Atlantic Region, working in cooperation with NMFS Northeast Fisheries Science Center (NEFSC), completed the first component, undertaking a scientific review of the life history and ecology, distribution and abundance, and an analysis of the ESA section 4(a)(1) factors. The Extinction Risk Assessment (ERA) was compiled by a biologist in NMFS' Greater Atlantic Region. The ERA was informed by invited workshop participants who based their individual expert opinions on the information contained in the scientific literature review. The workshop participants were comprised of a fisheries management specialist from NMFS' Highly Migratory Species Management Division, two research fishery biologists from NMFS' Northeast Fisheries Science Center, an elasmobranch expert from Sharks International, a fisheries manager from the New England Fishery Management Council, and a research director from the New England Aquarium. The workshop participants had expertise in elasmobranch biology and ecology, population dynamics, fisheries management, climate change and/or stock assessment science. The workshop participants reviewed the information from the scientific literature review. The status review report for thorny skate (NMFS 2017) compiles the best available information on the status of the species as required by the ESA, provides an evaluation of the discreteness and significance of populations in terms of the DPS policy, and assesses the current and future extinction risk, focusing primarily on threats related to the five statutory factors set forth above. We prepared this report to summarize the workshop participants' professional judgments of the extinction risk facing thorny skate. The workshop participants made no recommendations as to the listing status of the species, nor does the status review report. The status review report is available electronically at the Web site listed in ADDRESSES.
The status review report underwent 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 three independent specialists selected from government, academic, and scientific communities, with expertise in elasmobranch biology, conservation and management, and specific knowledge of thorny skates. The peer reviewers were asked to evaluate the adequacy, quality, and completeness of the data considered and whether uncertainties in these data were identified and characterized in the status review report, as well as to evaluate the findings made in the ``Assessment of Extinction Risk'' section of the report. They were also asked to specifically identify any information missing or lacking justification, or whether information was applied incorrectly in reaching conclusions. We addressed all peer reviewer comments prior to finalizing the status review report. Comments received are posted online at www.cio.noaa.gov/services_programs/prplans/ID365.html.
We subsequently reviewed the status review report, the cited references, and the peer review comments, and we concluded that the status review report, upon which this listing determination is based, provides the best available scientific and commercial information on thorny skate. Much of the information discussed below on thorny skate biology, genetic diversity, 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 and Significant Portion of its Range (SPR) policies in making the listing determination.
Distribution and Habitat Use
The thorny skate belongs to the family Rajidae, genus Amblyraja, and species radiata. The thorny skate is a widely distributed boreal species, spanning both sides of the Atlantic. In the western North Atlantic, it ranges from western
Greenland to South Carolina. In the eastern North Atlantic, it ranges from the Barents Sea southward to the southwestern coasts of Ireland and England, including Iceland (Bigelow and Schroeder, 1953). Found over a wide variety of substrates including sand, broken shell, gravel, pebbles and soft mud, the thorny skate ranges over depths from 18 to 1400 m (COSEWIC 2012).
Despite its generalist nature, some habitat preferences exist. There is some evidence that the species prefers complex hard bottom habitat instead of sand or mud. Scott (1982) reported that catch rates of thorny skate were highest on coarser grained sediment, and catch rates diminished as grain size decreased on the Scotian Shelf. Also, more skates are caught by longlines in bottom areas that are considered categorized as rough versus those considered smooth (Sosebee et al., in prep).
Generally, thorny skate appear to prefer deeper waters within their range, although the specific depth varies by location and may be impacted by other factors including temperature. Survey data from the inshore waters in the Gulf of Maine stratified by depth indicate catch by trawl survey gear increases sharply in depths greater than 40 meters (m), and peaks at around 95 m. Most individuals are caught between 70 m and the upper depth limit for the survey, 120 m (Sosebee et al., in prep). Generally, within U.S. waters, they range from a depth of 141 to 300 m in spring and 31 to 500 m in fall, with the majority of both spring and fall captures between 141 to 300 m (Packer et al., 2003). Previous studies found thorny skate most abundant between 111 m and 366 m throughout the U.S. range (McEachran and Musick 1975). In Canadian waters from the Labrador Shelf to the Grand Banks, 88 percent of thorny skate are found between 30 and 350 m (COSEWIC 2012). In the Gulf of St. Lawrence, thorny skate have been found to be increasingly concentrated in depths below 100 m since the early 1990s, with the majority of fish greater than 33 centimeters (cm) in length found around 200 m (Swain and Benoit 2006). Fish smaller than 33 cm concentrate in shallower waters around 100 m in the Gulf of St. Lawrence. In Norway, thorny skate show a preference for even deeper waters, being more concentrated between 600 and 650 m (Williams et al., 2008). Within the Barents Sea, average catch is highest between 100 and 200 m but thorny skates are captured all the way to 800 m (Dolgov et al., 2005a). Together, this information demonstrates that thorny skate occur in a wide range of depths throughout their range, but are most likely to occur in deeper waters.
Thorny skate have been caught at temperatures ranging from -1.4 to 14 degCelsius (C) (McEachran and Musick 1975); however, they have a more narrow thermal range than most sympatric species (Hogan et al., 2013). In the U.S. waters of the inshore Gulf of Maine, surveys catch nearly twice as many skates at 2.5 degC as between 4.5 and 9.5 degC, with catch rates dropping off sharply for temperatures warmer than 10 degC (Sosebee et al., in prep). Generally, in U.S. waters during spring, adult thorny skate were found at temperatures between 2 and 13 degC, with the majority between 4 and 7 degC. During the fall, they were found over a temperature range of 3 and 13 degC, with the majority found between 5-8 degC (Packer et al., 2003). Preliminary tagging results are available from a 2016 Gulf of Maine study with data from 23 thorny skate with pop-up satellite archival transmitting (PSAT) tags. The daily (min/max) temperature records from all PSAT-tagged skates indicated that thorny skate occurred in temperatures of 4.5-10.5 degC from November to August and have a broad temperature tolerance (J. Kneebone, pers. comm.). On the Grand Banks, catches of thorny skate are generally highest between 3 and 5 degC, although catch has concentrated on the warmer edge of the Bank since the 1990s (Colbourne and Kulka 2004). A similar concentration on the edge of the banks has been observed in the Gulf of St Lawrence, correlating with temperatures between 2 and 4 degC (Swain and Benoit, 2006). Few thorny skates were caught where temperature was 200m) they went from 3.71 percent in the early 1990s to 4.52 percent averaged from 2004-2010 (Tamdrari et al., 2014). This is a relatively small change for both depths when compared to change for other species, representing half as much decrease in the coastal assemblage as redfish (Sebastes spp.) and an order of magnitude less than the decrease in Atlantic cod (Gadus morhua). Additionally, thorny skates were most abundant between 100 and 350 m of depth before climate change became apparent (McEachran and Musick 1975), and this remains the case in modern surveys (Packer et al., 2003; COSEWIC 2012), though depths in the fall range up to 500 m in U.S. waters (Packer et al., 2003).
Recent climate vulnerability analyses have been performed for fish species in the Northeast United States and for fish assemblages on the Scotian Shelf in Canada. Despite having similar methodologies, these studies came to different conclusions regarding the vulnerability of thorny skates to climate change. Stortini et al. (2015) rated the vulnerability of the thorny skate on the Scotian shelf as ``low.'' This study scaled the estimated vulnerability relative to thirty-two other species found on the Scotian Shelf; therefore, the ``low'' vulnerability rating is in relation to other species in that location.
Hare et al. (2016) rated this species as having a ``high'' biological sensitivity and climate exposure likelihood off the Northeast United States, on a scale of ``low'' to ``very high.'' In this effort, vulnerability was equated to the likelihood of the species experiencing either reduced productivity or shifting its distribution out of the region in response to climate change. This vulnerability analysis concluded that there was also a ``high'' chance of negative impacts and changes in species distribution within its U.S. range. Both assessments used a similar variety of species life history factors to produce a species sensitivity score, but Hare et al., (2016) used a larger variety of climate factors including pH, salinity, precipitation and ocean currents to determine climate exposure, whereas Stortini et al. (2015) looked only at mean temperature under different warming scenarios.
While thorny skates in U.S. waters are at high risk for being impacted by climate change (likely to manifest as loss of cold water habitat in U.S. waters), the best available information indicates that throughout most of the range, the generalist habitat requirements of the thorny skate will limit impacts of climate change. This conclusion is supported by studies on species diversity that indicate impacts to species assemblages have not yet occurred on communities including the thorny skate, due to its depth preferences (Stefansdottir et al., 2010, Tamdarai et al., 2015). In addition, modeling predicts a less than 10 percent loss of thermally appropriate habitat before 2030 in U.S. waters, but almost no habitat loss before 2030 in Canadian waters (Shackell et al., 2014). A ten percent loss is expected in Canada and up to 25 percent loss in U.S. waters may occur before 2060 (Shackell et al., 2014). Although the risk may be high that thorny skates will shift their distribution out of Northeast U.S. waters due to warming ocean conditions (Hare et al., 2016), the species would have the ability to persist in adjacent regions with more suitable habitat.
Ocean temperature changes due to climate change may be contributing to a contraction of the thorny skate's range at its southern edges. Thorny skates appear to have comparatively low exposure to potentially harmful pollutants, and there is no information suggesting their individual fitness or populations are threatened by pollution. The mean score we calculated based on the workshop participants' individual scores indicates that climate change and non-fishing related modifications to habitat (e.g. drilling, offshore windfarm construction) present a low to moderate contribution to extinction risk.
Overutilization: The workshop participants individually evaluated the available information on fishing mortality and abundance trends of thorny skate summarized in the status review report. Overutilization for commercial purposes was once considered one of the primary threats to thorny skate populations. Significant declines have been documented throughout much of the thorny skate's range due to historical fishing pressure. The most recent information suggests that declines in several stocks have halted due to fishing restrictions (COSEWIC 2012; ICES 2015; Sosebee et al., in prep). Populations appear to be stable or slowly increasing, with millions of individuals remaining in the Northwest Atlantic alone. Therefore, there appears to be a low likelihood of further population declines because of stabilization observed after management actions were put into place. The mean score we calculated based on the workshop participants' individual scores corresponds to a very low or low ranking for all threats in this category, with the commercial landings and commercial discards receiving mean scores of slightly higher than low contributions to overall extinction risk.
Thorny skates were and are taken as bycatch by fisheries throughout their range, including those in the North Sea, Barents Sea, Gulf of St. Lawrence and on the Canadian and U.S. continental shelves. Targeted fisheries, particularly by foreign fleets including those of Spain, Portugal and Russia, developed in the 1990s (COSEWIC 2012; Sosebee et al., in prep). The fishery for thorny skates was largely unregulated in the Northwest Atlantic until the 2000s (COSEWIC 2012). Currently, small fisheries exist in the North Sea (Piet et al., 2009) and on the Grand Banks in Canada (Simpson et al., 2016), which is, as mentioned earlier, the first regulated skate fishery in international waters. Since 2003, U.S. vessels have been prohibited from possessing or landing thorny skates (NEFMC 2009). While directed fisheries on the species are currently limited, thorny skates continue to be taken as bycatch and discarded in commercial fisheries within their range.
U.S. Fisheries Catch and Bycatch
Total landings for all skate species within U.S. waters reached 9,462 mt in 1969 and declined after that, reaching a low of 847 mt in 1981 (Sosebee et al., in prep). Skate landings increased substantially after that time period for lobster bait and export, rising to a high of 20,342 mt in 2007 (Sosebee et al., in prep). Estimated total catch of thorny skates has declined from over 5,000 mt in the late 1960s and early 1970s to about 200-300 mt in recent years (Sosebee et al., in prep). Thorny skates make up a small overall portion of skate catch, particularly in comparison to winter and little skates. Most of the
early catch (1969-1989) was from otter trawl discards, while landings dominated from 1990 to present (Sosebee et at., in prep). Discards from scallop dredges increased in proportion to population estimates during the late 1970s and again during the late 1990s (Sosebee et al., in prep). While landings were generally low, catch of thorny skates likely contributed to the decline of the species over time.
In 2003, the NEFMC implemented a FMP for the seven skates present within the Gulf of Maine. The FMP prohibited landings of thorny skates as the stock status was considered overfished (NEFMC 2009). The limited information regarding species biomass required the NEFSC to develop survey-based overfished and overfishing reference points for the thorny skate: ``Thorny skate is in an overfished condition when the three-year moving average of the autumn survey mean weight-per-tow is less than one half of the 75th percentile of the mean weight-per-tow observed in the autumn trawl survey from the selected reference time series. Overfishing occurs when the three year moving average of the autumn survey mean weight per tow declines 20% or more, or when the autumn survey mean weight per tow declines for three consecutive years. The reference points and selected time series may be re-specified through a peer reviewed process and/or as updated stock assessments are completed'' (NEFMC 2009). The target biomass for thorny skates is currently set at 4.13 kg/tow and the minimum biomass threshold at 2.06 kg/tow. The most recent 3-year average remains below these figures at 0.17 kg/tow; however, this figure has remained steady since 2011.
The MSA states: ``A stock or stock complex is considered ``overfished'' when its biomass has declined below a level that jeopardizes the capacity of the stock or stock complex to produce Maximum Sustainable Yield (MSY) on a continuing basis. MSY is defined as the largest long-term average catch or yield that can be taken from a stock or stock complex.'' The overfished/overfishing status of a stock is determined relative to its ability to produce continued yield from a fishery. The overfished status of thorny skates within the United States means that fishing mortality rates (including past landings and discards) have been too high, and caused the population to decline below acceptable levels. The stock must be rebuilt to biomass levels that can produce MSY for a fishery to be sustainable. The prohibition on harvest in U.S. waters is expected to help the stock rebuild. This means any thorny skates caught within U.S. waters must be discarded at sea.
Estimated thorny skate discards are low relative to other skates (Sosebee et al., in prep). Landings and dead discards have decreased in recent years (2007-2014) and total discards have stabilized or increased.
Canadian Fisheries and Bycatch
Thorny skates comprise the majority of skates caught in commercial fisheries in Canada. The majority of thorny skate catch comes from the coast of Labrador and Newfoundland, including the Grand Banks area. This has ranged from a high of approximately 24,000 mt in the early 1990s to current levels around 6,000 mt. Relative fishing mortality has remained stable (1985- 2009) in this area at approximately ten percent (COSEWIC 2012).
Within the southern Gulf of St. Lawrence, estimated landings of thorny skates peaked in 1994 at approximately 38 t, and have since decreased to an average 1-2.7 t over the period 2006-2011(Benoit 2013). The thorny skate is the most common discarded skate species. On average, 490 t were discarded in the early 1990s, this dropped to 53.7 t on average over the period 2006 -2011 (Benoit 2013). While the majority of discards in the past came from trawl fisheries, currently half are from trawl and half from the gillnet fishery for Greenland halibut (Benoit 2013). Overall fishing effort in this area has declined or remained stable since the 1990s (COSEWIC 2012).
The only remaining directed fishery for the thorny skate is executed within the Grand Banks Area. This area is managed between two areas, 3Ps directly south of Newfoundland and entirely within the Canadian Exclusive Economic Zone (EEZ), and divisions 3LNO, which comprise the outer banks, some of which lies outside the Canadian EEZ. Quota regulation within the EEZ was enacted in 1995 (Simpson et al., 2014). In 2004, NAFO enacted quota regulation for the entire 3LNO area, making this the first regulated skate fishery in the world in international waters. The regulated areas include areas within and outside the Canadian EEZ; 3Ps remained under Canada's quota system. For most years since the quotas were enacted, catch has remained well below the limits. Relative fishing mortality within the Grand Banks has decreased over time. Within the 3LNO it increased from the late 1980s to a peak of 29 percent in 1997; then stabilized at approximately 17 percent during 1998-2004 (Simpson et al., 2016). In 2005, relative fishing mortality declined to 4 percent and has remained around 5 percent (Simpson et al., 2016). Since 1985, fishing mortality within 3Ps was relatively constant, below 5 percent for most years (Simpson et al., 2016).
Northeast Atlantic Fisheries and Bycatch
There is little directed fishing effort on thorny skates across most of the Northeast Atlantic, with a prohibition against landings currently in place in European Union waters in the Barents Sea and east of the United Kingdom (ICES 2015). There is a small fishery landing thorny skates from Iceland and Greenland. Landings here have increased but still remain below 2,000 mt, or about half that of Canada's yearly landings.
The available information indicates that current thorny skate populations are numerous in many areas and that area occupied is increasing. While the portion of the population within the United States is not currently capable of sustaining a fishery, fisheries for thorny skates are well-controlled throughout the range. Fishing mortality relative to biomass has decreased across the range through time, and is currently rather low in most areas. The mean score we calculated based on the workshop participants' individual scores indicate that commercial landings across the range of the species present a low contribution to extinction risk.
We have also considered the best available information on the mortality rates of thorny skates that are discarded (i.e., returned to the water alive after capture in fishing gear). Factors that impact thorny skate discard survival in trawl fisheries include size, depth of capture, difference in temperature between bottom and surface conditions (Benoit et al., 2013), duration of the tow and degree of injury sustained during the capture event (Mandelman et al., 2013). Skates can have an overall high survival rate following discard, with up to 20 percent mortality predicted for trawl fisheries within the Gulf of St. Lawrence (Benoit, 2013). Mandelman et al. (2013) studied the post-discard mortality of thorny skates captured in trawl gear in the Gulf of Maine. This study indicates that while 72-hour post-discard mortality of a sample of individuals retained in captivity following cage trials was only 22 percent, the condition of many of the individual thorny skates was poor (52 percent injury rate at time of capture; most with listless appearance and lack of vigor at the end of the 72-hour period) and 7-day mortality was 66 percent. The authors note that the species may be less resilient than
indicated by the 22 percent 72-hour mortality rate and cautions against the use of the 22 percent mortality rate in management. The effects of captivity on these mortality rates are unknown; however, it is reasonable to expect that captivity contributed to slightly higher mortality rates. The available information indicates a low to moderate risk of mortality to a thorny skate once it is captured (Benoit et al., 2013 and Mandelman et al., 2013). The elimination of most directed fisheries and reductions in catches are expected to reduce overall fishing mortality, including discard mortality. It is also important to note that post-discard mortality is considered in developing fishing management policies for the thorny skate in the United States. Current management measures consider the available information on post-discard mortality. While overutilization had been a primary threat to the species, fishing mortality is being managed throughout the species' range. The available information indicates that current thorny skate populations are numerous in many areas and that area occupied is increasing. While the portion of the population within the United States is not currently capable of sustaining a fishery, fisheries for thorny skates are well-controlled throughout the range. Fishing mortality relative to biomass has decreased across the range through time, and is currently low in most areas. The mean score we calculated based on the workshop participants' individual scores indicates that commercial discards across the range of the species represent a low contribution to overall extinction risk.
Disease and Predation: Workshop participants individually evaluated the available information on disease and predation of thorny skates summarized in the status review report. Overall, there is minimal information available with which to evaluate these threats. In general, thorny skates may be susceptible to diseases, but there is no evidence that disease has ever caused declines in populations. The mean score we calculated based on the workshop participants' individual scores indicates that disease represents a very low contribution to overall extinction risk, as it is very unlikely that this threat contributes or will contribute to the decline of the species.
Regarding predation, there is no indication that this species would be threatened by excessive predation pressure. Egg capsules for the species are reportedly preyed upon by halibut, Greenland shark and goosefish (Collette and Klein-MacPhee 2002). Gastropods may also predate on egg cases, with a predicted predation frequency ranging from 4 to 18 percent (Cox et al., 1999). It is unknown what the effect of this predation may be, but it could contribute to a slower rate of rebuilding.
Skates, including thorny skates, are prey for a number of species: Flounder, other skates, seabirds, marine mammals, sharks, cod and other large demersal fishes, with the last being the most important (Morissette et al., 2006). Overall mortality for small skates has decreased while increasing for larger skates since the 1970s. Currently, recruitment for smaller skates remains high in portions of the Canadian range (Benoit and Swain 2011; Swain et al., 2013). Meanwhile, the numbers of large fishes have decreased. Fishing pressure has also decreased, substantially in some regions, indicating sources of adult skate mortality may be natural. Marine mammal predation, particularly by gray seals, has been suggested as an increasing cause of mortality for some locations (Swain et al., 2013).
Thorny skates are at least a minor source of prey for gray seals, composing up to 6 percent of their diet depending on age and season (Beck et al., 2007). Gray seal energy requirements are high enough that this predator may be responsible for much of the natural mortality of adult thorny skates in some areas, despite the thorny skate being a minor prey source (Swain et al., 2013, Benoit et al., 2011). Energetics modeling has been found to explain a similar pattern of increased adult mortality in other local species (Benoit et al., 2011). Further modeling work found a negative relationship between the gray seal index and thorny skate numbers in the Southern Gulf of St. Lawrence. The harp seal index was more likely to explain population trends in the Northwest portion of the Gulf. Predation by either species was not found to explain trends in thorny skate within the northeast portion of the Gulf (Ouellet et al., 2016).
Predation by gray seals may have increased within the range of the thorny skate. Gray seal populations have recovered during the same time period of decreasing mortality for small thorny skates. Numbering only 15,000 individuals in the 1960s, the gray seal population increased to 350,000 by 2007. In 2014, the population estimate within the Canadian range and Gulf of Maine had increased to 505,000 (Hamill et al. 2014). In addition, gray seals have been expanding their range and are now present in small numbers as far south as Southern New England (DiGiovanni Jr. et al., 2016).
Gray seals stay mostly local (within 50 km) to haul-out sites and forage in mostly shallow depths (~100 m) (McConnell et al., 1999, Schreer et al., 2001). The largest numbers of gray seals are found in the Gulf of St. Lawrence and on Sable Island off the coast of Nova Scotia, where they may impact skates on the Scotian Shelf. Smaller populations are found in coastal Nova Scotia, Seal Island, Maine and on Cape Cod, Massachusetts (Hamill et al., 2014). If gray seal predation is contributing to thorny skate mortality, the impact is likely to be concentrated in the shallowest portions of the thorny skate range around major gray seal population areas.
Harp seals migrate to the Gulf of St. Lawrence to whelp before returning to Artic waters on the overlapping range of thorny skate. They migrate along the coast of Labrador and Greenland northward. Small numbers of harp seals may remain year-round in southern waters, with the majority living in the Artic. Currently there is no evidence that thorny skates comprise more than an incidental portion of the harp seal diet. Harp seal reproductive rates decreased in the latest assessment, with 8.3 million individuals estimated in 2008 and 7.7 million estimated in 2012 (DFO 2012). Harp seal predation on thorny skates is likely stable or slightly decreasing and centered around whelping sites.
Modeling indicates marine mammal predation may contribute to high natural mortality of adult thorny skates in some discrete areas, suppressing recovery of their populations (DFO 2012). For now, high levels of recruitment in small skates are still evident despite this pressure. Recent abundance of thorny skates has also been stable in areas where marine mammal populations are centered. The recent population increase of gray seals in U.S. waters and coinciding stabilization of thorny skate abundance indices suggests that seal predation was not likely responsible for thorny skate declines. The mean score we calculated based on the workshop participants' individual scores indicates that predation represents a very low contribution to extinction risk, as it is very unlikely that this threat contributes or will contribute to the decline of the species.
Inadequacy of Existing Regulatory Mechanisms: The workshop participants individually evaluated the available information on fisheries management regulations and abundance trends of the thorny skate summarized in the status review report. The inadequacy of regulatory mechanisms to control the harvest of thorny skates was once considered a significant threat to their populations. Legal protections for
thorny skates vary between outright prohibitions on landings in the United States and much of the Northeast Atlantic, with limited fishing permitted in Canada and Iceland.
Within U.S. waters, thorny skates are managed under the MSA. Landings of thorny skates within U.S. waters were unregulated until 2003 when the NEFMC established an FMP for the skate complex. At that time, the stock was deemed ``overfished'' and a landing prohibition was put in place, requiring all catch of thorny skates to be discarded at sea. At that time, the same prohibitions were put into place for the sympatric species, barndoor and smooth skates, to help rebuild these stocks. The skate complex FMP does still allow catch of other skate species, and other fisheries may also catch thorny skates but are likewise required to discard them.
MSA regulations are enforced in U.S. waters by the U.S. Coast Guard, NOAA's Office of Law Enforcement and state partners. Fishermen who do not comply with regulations established under the MSA are subject to fines and criminal penalties, depending on the severity of the offense. Compliance with the prohibition against landing thorny and other skates was examined via port sampling. In 2005, 3.61 percent of skate wing landings were identified as thorny skate. In the years since, this declined rapidly with less than 1 percent of wings identified as thorny skate in 2007, and further declined to 0.01 percent in 2012, indicating that compliance with the discard regulations and misidentifications or mislabeling is not an issue in the United States (Curtis and Sosebee 2015). While the thorny skate is still considered overfished within the United States, overfishing is no longer occurring (NEFMC 2009), indicating that fishery management measures are successfully controlling fishing mortality in those waters.
Under the Fisheries Act, Canadian fisheries may take thorny skates as bycatch in other fisheries, and a small, directed fishery still operates on the Grand Banks. Available information suggests that catch is well below the total allowable catch limits as set by NAFO and Canada, indicating fishing mortality is controlled (Simpson et al., 2016). The Scotian shelf has been closed to directed fishery for skates (thorny and winter) since the early 2000s. In addition to compliance with catch limits, thorny skate abundance has been stable on the Grand Banks and the rest of Canada, yet still below historical levels (COSEWIC 2012). Recruitment in this portion of the species' range remains relatively high. Therefore, existing regulatory measures appear sufficient to control fishing mortality.
Northeast Atlantic Regulations
There is a prohibition against landing thorny skates from European Union waters in the Barents Sea and east of the United Kingdom (ICES 2015). A very small fishery exists in Iceland and off East Greenland, where survey numbers have remained stable since 2000 (ICES 2015). With populations within the Northeast Atlantic currently considered stable (ICES 2015), existing regulatory measures appear sufficient to control fishing mortality within this region. Iceland reported 1625 t of thorny skate landings in 2014. A 2016 EU regulation prohibits thorny skate landings in EU waters of ICES divisions IIa, IIIa and VIId and ICES subarea IV Subareas II and IV and Division IIIa (Norwegian Sea, North Sea, Skagerrak, and Kattegat), based on ICES advice that a precautionary approach dictates no targeted fishing and measures to reduce bycatch. ICES advice for this species west of the UK is currently pending. Thorny skates taken from these EU waters are counted under a regional EU skate quota that lacks a robust scientific basis. EU limits on these species have been generally trending toward more precautionary over the last decade.
Legal protections for thorny skates vary between outright prohibitions on landings in the United States and much of the Northeast Atlantic, with limited fishing permitted in Canada and Iceland. While thorny skates are also a bycatch species within many fisheries, stable population numbers indicate existing protections are sufficient through its range. The mean score we calculated based on workshop participants' individual scores for both global/national climate change regulations and NAFO fishing regulations indicate that inadequacy of these regulations represents a low to moderate contribution to extinction risk. However, workshop participants also noted uncertainty related to other global or national environmental regulations in this category because there is more uncertainty in their effectiveness to result in protections for marine ecosystems.
Other Natural or Manmade Factors Affecting the Thorny Skate's Continued Existence
The workshop participants individually evaluated the available information on other potential threats as summarized in the status review report. Natural threats focused on the thorny skate's inherent biological vulnerability, which is also reflected in the demographic factors described above. The species has low productivity because of its life history characteristics and is vulnerable to exploitation and population perturbations. Populations can be quickly depleted and take many years to recover. However, their mobility, high genetic diversity, and generalist habitat and diet strategy contribute to a low risk of extinction. The mean scores we calculated based on workshop participants' individual scores indicate that both manmade catastrophic events and stochastic events represent very low contributions to extinction risk because of the wide geographic distribution of the species.
Summary of Demographic Factors and Threats Affecting Thorny Skate
Both demographic factors and threats were qualitatively ranked on a scale from very low to very high by the workshop participants (NMFS 2017). No demographic factors or threats were ranked high or very high. Abundance, diversity and spatial structure/connectivity were ranked very low to low, and growth rate/productivity was ranked low to moderate risk. For the workshop participants' threats assessments, both climate change and global or national climate change regulations received the most likelihood points in the moderate contribution to extinction risk category. Only one threat, climate change, received likelihood points in the high contribution category, though the majority of points were in the moderate contribution category. No threats considered by workshop participants were given an overall average score of medium, high or very high contributions to extinction risk of thorny skate. All workshop participants placed their individual point allocations in the very low contribution to extinction risk category for the following threats: Recreational fishing, recreational discards, educational collection, and stochastic events.
The only demographic factor ranked above low was growth rate/
productivity (low to moderate risk). The thorny skate's life history traits make the populations vulnerable to threats and slow to recover from depletion. Once we compiled the individual workshop participant scores and calculated the mean score, only six threats were ranked in the low to moderate category, all others were in the very low to low categories. The threats ranked low to moderate included: Climate change,
manmade non-fishing habitat impacts, commercial discards, commercial landings, global and national climate regulation, and inadequacy of existing NAFO regulations. Fishing for thorny skates is managed throughout the species' range. Efforts to manage the harvest of the species include regulations put forth by the United States, Canada, NAFO, and ICES, though workshop participants expressed uncertainty in the adequacy of NAFO regulation. Due to these recent management efforts, thorny skate abundance has stabilized in the several regions (e.g., United States, South Labrador Shelf, North Gulf of St. Lawrence, Norway) and has increased in some waters (e.g. Grand Banks). Given its life history traits, return to historical abundances may take decades, but demographic risks are mostly low and significant threats have been reduced.
Overall Risk Summary
As described previously, the workshop participants used a ``likelihood analysis'' to evaluate the overall risk of extinction. Each workshop participant had 10 likelihood points to distribute among the following overall extinction risk categories: Low risk, moderate risk or high risk.
Overall, the mean scores we calculated based on the workshop participants' individual scores indicate that rangewide, thorny skates have a 93.3 percent likelihood of being at low risk of extinction, 6.6 percent likelihood of moderate risk of extinction, and 0 percent likelihood of high risk of extinction.
The mean scores we calculated based on the workshop participants' individual scores indicate that, overall, the thorny skate is at low risk of extinction. None of the workshop participants indicated that there was any likelihood of the thorny skate having a high risk of extinction. Additionally, there was very little likelihood of a moderate risk of extinction (4 points out of 60 total).
Thorny skates have been subjected to considerable fishing pressure for many decades, but improved fisheries management efforts in recent years have reduced fishing mortality rates on thorny skate stocks, and populations are no longer declining. Return to historical abundance may take decades, but demographic risks are mostly low and significant threats have been reduced. Based upon the available information summarized here, the mean scores we calculated based on the workshop participants' individual scores indicate that the thorny skate has a low risk of extinction, assuming the dominant threats to its populations continue to be managed. We have no reason to believe that these dominant threats will not continue to be managed.
We have independently reviewed the best available scientific and commercial information, including the status review report (NMFS 2017) and other published and unpublished information. We conclude that the thorny skate is not in danger of extinction or likely to become so in the foreseeable future throughout its range. As described earlier, an endangered species is ``any species which is in danger of extinction throughout all or a significant portion of its range'' and a threatened species is one ``which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.'' The workshop participants individually ranked the demographic criteria and the five factors identified in the ESA, completed an assessment of overall extinction risk, and each submitted his/her individual expert opinions to us. We reviewed the results of the ERA and concurred with the workshop participant's individual expert opinions regarding extinction risk. We then applied the statutory definitions of ``threatened species'' and ``endangered species'' to the ERA results and other available information to determine if listing the thorny skate was warranted.
The mean scores we calculated based on the ERA workshop participant scores indicate that the level of extinction risk to the thorny skate is low, with 93.3 percent of the workshop participants' likelihood points allocated to the ``low risk'' category. The workshop participants allocated only 6.6 percent of their likelihood points to the ``moderate extinction risk'' category. Given this low level of extinction risk, which is based on an evaluation of the contribution of the thorny skate's demographic parameters and threats to extinction risk, we have determined that the thorny skate does not meet the definition of an endangered or threatened species and, as such, listing under the ESA is not warranted at this time.
Significant Portion of Its Range
Though we find that the thorny skate rangewide is not in danger of extinction now or in the foreseeable future, under the SPR Policy, we must go on to evaluate whether these species are in danger of extinction, or likely to become so in the foreseeable future, in a ``significant portion of its range'' (79 FR 37578; July 1, 2014).
When we conduct an SPR analysis, we first identify any portions of the range that warrant further consideration. The range of a species can theoretically be divided into portions in an infinite number of ways. However, there is no purpose to analyzing portions of the range that are not reasonably likely to be significant or in which a species may not be endangered or threatened. To identify only those portions that warrant further consideration, we determine whether there is substantial information indicating that (1) the portions may be significant and (2) the species may be in danger of extinction in those portions or likely to become so within the foreseeable future. We emphasize that answering these questions in the affirmative is not a determination that the species is endangered or threatened throughout a significant portion of its range--rather, it is a step in determining whether a more detailed analysis of the issue is required (79 FR 37578; July 1, 2014). Making this preliminary determination triggers a need for further review, but does not prejudge whether the portion actually meets these standards such that the species should be listed.
If this preliminary determination identifies a particular portion or portions for potential listing, those portions are then fully evaluated under the ``significant portion of its range'' authority as to whether the portion is both biologically significant and endangered or threatened. In making a determination of significance, we consider the contribution of the individuals in that portion to the viability of the species. That is, we determine whether the portion's contribution to the viability is so important that, without the members in that portion, the species would be in danger of extinction or likely to become so in the foreseeable future.
The SPR policy further explains that, depending on the particular facts of each situation, we may find it is more efficient to address the significance issue first, but in other cases, it will make more sense to examine the status of the species in the potentially significant portions first. Whichever question is asked first, an affirmative answer is required to proceed to the second question. Id. ``If we determine that a portion of the range is not `significant,' we will not need to determine whether the species is endangered or threatened there; if we determine that the species is not endangered or threatened in a portion of its range, we will not need to determine if that portion is `significant' '' (79 FR 37587). Thus, if the answer to the first question is negative--whether it addresses the significance question or
the status question--then the analysis concludes, and listing is not warranted.
As described previously, we determined that there are no DPSs of the thorny skate, and rangewide, the thorny skate is at a low risk of extinction. Applying the SPR policy to the thorny skate, we first evaluated whether there is substantial information indicating that any portions of the species' range may be significant. After a review of the best available information and invited experts' opinions, as described below, we find that the data do not indicate any portion of the thorny skate's range as being more significant than another. Thorny skates are distributed across the North Atlantic and have very few restrictions governing their movements. Movements are restricted by depth and temperature; however, there are no known gaps in suitable habitat, thus allowing a continuous range. Because the Northwest Atlantic and the Northeast Atlantic are the two largest portions of the species' range, the workshop participants individually considered the SPR questions related to abundance, productivity, spatial distribution, and diversity outlined in the NMFS listing guidance. As explained below, we determined that neither the Northwest Atlantic nor the Northeast Atlantic were significant portions. Given that neither the Northwest Atlantic nor the Northeast Atlantic represents a significant portion of the range, we do not find that thorny skate in U.S. waters represent a significant portion of the range of the thorny skate. The following questions related to significance of portions were considered:
Without that portion, would the level of abundance of the remainder of the species cause the species to be at moderate or high risk of extinction due to environmental variation or anthropogenic perturbations (of the patterns and magnitudes observed in the past and expected in the future)?
Without that portion, would the abundance of the remainder of the species be so low, or variability in abundance so high, that it would be at moderate or high risk of extinction due to depensatory processes?
Without that portion, would abundance of the remainder of the species be so low that its genetic diversity would be at risk due to inbreeding depression, loss of genetic variation, or fixation of deleterious alleles?
Without that portion, would abundance of the remainder of the species be so low that it would be at moderate or high risk of extinction due to its inability to provide important ecological functions throughout its life-cycle?
Without that portion, would the abundance of the remainder of the species be so low that it would be at risk due to demographic stochasticity?
Without that portion, would the average population growth rate of the remainder of the species be below replacement such that it would be at moderate or high risk of satisfying the abundance conditions described above?
Without that portion, would the average population growth rate of the remainder of the species be below replacement such that it is unable to exploit requisite habitats/niches/etc. or at risk due to depensatory processes during any life-history stage?
Without that portion, would the remainder of the species exhibit trends or shifts in demographic or reproductive traits that portend declines in the per capita growth rate, which pose a risk of satisfying any of the preceding conditions?
Will the loss of one or more of the portions significantly increase the risk of extinction to the species as a whole by making the species more vulnerable to catastrophic events such as storms, disease or temperature anomalies?
Will connectivity between portions of the species' range be maintained if a portion is lost (e.g., does the loss of one portion of the range of the species create isolated groups or populations?)?
Are there particular habitat types that the species occupies that are only found in certain portions of the species' range? If so, would these habitat types be accessible if a portion or portions of the range of the species are lost?
Are threats to the species concentrated in particular portions of the species' range and if so, do these threats pose an increased risk of extinction to those portions' persistence?
Will unique genetic diversity be lost if a portion of the range of the species is lost?
Does the loss of this genetic diversity pose an increased risk of extinction to the species?
As described more fully in the status review report and below, the workshop participants individually answered ``no'' to all of the abundance, productivity and diversity questions related to whether the Northwest Atlantic or the Northeast Atlantic portion represent a significant portion of the species' range. One workshop participant answered ``yes'' to two spatial distribution questions.
Given estimates of 1.8 billion animals in Northwest Atlantic waters, which represent 30-40 percent of the overall population, loss of the Northwest Atlantic population would have a large impact on the species rangewide, but would not put the species at a moderate or high risk of extinction because of the remaining large population size and wide geographic distribution. When considering productivity, the group noted that the average growth rate for the species does not depend on the growth rate in the Northwest Atlantic and vice versa for the Northeast Atlantic and that the areas do not exhibit source-sink dynamics. There was no evidence that without either area the average population growth rate of the remainder of the species would drop below replacement, resulting in the population being unable to exploit requisite habitat, nor was there any evidence that the remainder of the species would be at risk due to depensatory processes. Regarding shifts in demographic or reproductive traits, the group could not identify evidence that a decline in the Northwest Atlantic would result in a decline in the Northeast Atlantic. Given the large spatial distribution of the thorny skate and the foreseeable future of 40 years, the group could not identify a stochastic event that could impact the entire Northwest Atlantic or Northeast Atlantic distribution of the thorny skate. There is no information to suggest that loss of any portion would severely fragment and isolate the species to the point where individuals would be precluded from moving to suitable habitats or have an increased vulnerability to threats. The loss of either the Northwest Atlantic population or the Northeast Atlantic population would result in the loss of connectivity rangewide, given that it is a continuous population. However, loss of the Northwest Atlantic population would not affect spatial connectivity of the Northeast Atlantic population and vice versa. Some genetic differentiation is present between the Northwest and Northeast Atlantic, but the central portion of the range appears to bridge diversity between these two areas. This is likely made possible by the continuous distribution and depth range of the species. There is no substantial evidence to indicate that the loss of genetic diversity from one portion of the species' range would result in the remaining populations lacking enough
genetic diversity to allow for adaptations to changing environmental conditions. Based on the best available genetic research, thorny skates have the highest genetic diversity out of 15 studied skate species (Lynghammar et al., 2014), and the highest diversity occurs in waters near Iceland and Greenland. Due to the genetic diversity present in thorny skates across the species' range, loss of either the Northeast Atlantic population or Northwest Atlantic population would not present a significant increase in the extinction risk to the species.
The petitioners identified the U.S. population as a potential DPS. As noted above, this portion does not qualify as a DPS. We considered whether U.S. waters could be a significant portion of the species' range. However, due to the workshop participants individual expert opinions related to abundance, productivity, spatial distribution, and diversity questions for the larger Northwest Atlantic and Northeast Atlantic populations and our findings that neither of these constitute a significant portion of the species' range, and given the United States represents only a small portion of the global range of the thorny skate, there is little evidence for concluding that the U.S. population is significant to the entire species under the SPR policy. Furthermore, there is no indication that loss of the U.S. portion of the species' range would result in a moderate or high extinction risk to the global species. As was mentioned previously, the available population and trend data do not indicate that past declines in the United States have affected global populations of thorny skate. Thus, the United States population would not qualify as ``significant'' under the SPR Policy. Likewise, there is no substantial evidence to indicate that the loss of genetic diversity from one portion of the species' range would result in the remaining populations lacking enough genetic diversity to allow for adaptations to changing environmental conditions. Similarly, there is no information to suggest that loss of any portion would severely fragment and isolate the species to the point where individuals would be precluded from moving to suitable habitats or have an increased vulnerability to threats. In other words, loss of any portion of its range would not likely isolate the species to the point where the remaining populations would be at risk of extinction from demographic processes.
In summary, areas exhibiting source-sink dynamics, which could affect the survival of the species, were not evident in any part of the thorny skate's range. There is also no evidence of a portion that encompasses aspects that are important to specific life history stages, but another portion that does not, where loss of the former portion would severely impact the growth, reproduction, or survival of the entire species. In other words, the viability of the species does not appear to depend on the productivity of the population or the environmental characteristics in any one portion. It is important to note that the overall distribution of the thorny skate is still uncertain. As better data become available, the species' distribution (and potentially significant portions of its range) will become better resolved. However, at this time, there is no evidence to suggest that any specific portion of the species' range has increased importance over another with respect to the species' survival. We reviewed the individual workshop participants' expert opinions and application of the SPR policy. We conclude that under the SPR policy, the preliminary determination that a portion of the species' range may be both significant and endangered or threatened has not been met. Therefore, listing the thorny skate based on it being threatened or endangered in a significant portion of its range is not warranted under the SPR policy.
Section 4(b)(1) of the ESA requires that listing determinations be based solely on the best scientific and commercial data available after conducting a review of the status of the species and taking into account those efforts, if any, being made by any state or foreign nation, or political subdivisions thereof, to protect and conserve the species. We have independently reviewed the best available scientific and commercial information, including the petition, information submitted in response to the 90-day finding (80 FR 65175; October 28, 2015), the status review report (NMFS 2017), and other published and unpublished information cited herein, and we have consulted with species experts and individuals familiar with the thorny skate. We identified no DPSs of the thorny skate and therefore considered the species rangewide. We considered each of the section 4(a)(1) factors to determine whether any one of the factors contributed significantly to the extinction risk of the species. We also considered the combination of those factors to determine whether they collectively contributed significantly to extinction risk. As previously explained, we could not identify any portion of the species' range that met both criteria of the SPR policy. Therefore, our determination set forth below is based on a synthesis and integration of the foregoing information, factors and considerations, and their effects on the status of the species throughout its range.
We conclude that the thorny skate is not in danger of extinction, nor is it likely to become so in the foreseeable future throughout all or a significant portion of its range. We summarize the factors supporting this conclusion as follows: (1) The species is broadly distributed over a large geographic range within the North Atlantic Ocean, with no barrier to dispersal; (2) genetic data indicate that populations are not isolated and that the species has high genetic diversity, (3) while the species possesses life history characteristics that increase its vulnerability to overutilization, overfishing is not currently occurring within the range; (4) the best available information indicates that abundance and biomass has stabilized rangewide and on the edge of the range in U.S. waters; (5) current thorny skate populations are numerous in many areas and the area occupied is increasing; (6) while the current population size has declined from historical numbers, the population size is sufficient to maintain population viability into the foreseeable future and consists of at least millions of individuals; (7) a main threat to the species is fishery-related mortality from incidental catch (bycatch); however, there are strict management measures in place to minimize this threat throughout the species' range, and these measures appear to be effective in addressing this threat as evidenced by stabilizing numbers of thorny skates; (8) there is no evidence that disease or predation is contributing to increasing the risk of extinction; and (9) there is no evidence that the species is currently suffering from depensatory processes (such as reduced likelihood of finding a mate or mate choice or diminished fertilization and recruitment success) or is at risk of extinction due to environmental variation or anthropogenic perturbations.
Since the thorny skate is not in danger of extinction throughout all or a significant portion of its range or likely to become so within the foreseeable future, it does not meet the definition of a threatened species or an endangered species. Therefore, the thorny skate does not warrant listing as threatened or endangered at this time.
Thorny skates in the Atlantic Ocean from West Greenland to New York were
identified as a NMFS ``species of concern'' in 2006. A species of concern is one for which we have concerns regarding status and threats but for which insufficient information is available to indicate a need to list the species under the ESA. In identifying species of concern, we consider demographic and genetic diversity concerns; abundance and productivity; distribution; life history characteristics and threats to the species. Given the information presented in the status review report and the findings of this listing determination, we are removing the thorny skate from the ``species of concern'' list.
A complete list of all references cited herein is available upon request (see FOR FURTHER INFORMATION CONTACT).
The authority for this action is the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: February 21, 2017.
Alan D. Risenhoover,
Acting Deputy Assistant Administrator for Regulatory Programs, National Marine Fisheries Service.
FR Doc. 2017-03644 Filed 2-23-17; 8:45 am
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