Albacore tuna, Bigeye tuna, Blackfin tuna, Skipjack tuna, Yellowfin tuna Thunnus alalunga, Thunnus obesus, Thunnus atlanticus, Katsuwonus pelamis, and Thunnus albacares Image Monterey Bay Aquarium Atlantic Purse Seine Disclaimer December 8, 2014 Alexia Morgan, Consulting researcher Seafood Watch strives to have all Seafood Reports reviewed for accuracy and completeness by external scientists with expertise in ecology, fisheries science and aquaculture. Scientific review, however, does not constitute an endorsement of the Seafood Watch program or its recommendations on the part of the reviewing scientists. Seafood Watch is solely responsible for the conclusions reached in this report.
2 About Seafood Watch Monterey Bay Aquarium s Seafood Watch program evaluates the ecological sustainability of wildcaught and farmed seafood commonly found in the United States marketplace. Seafood Watch defines sustainable seafood as originating from sources, whether wild-caught or farmed, which can maintain or increase production in the long-term without jeopardizing the structure or function of affected ecosystems. Seafood Watch makes its science-based recommendations available to the public in the form of regional pocket guides that can be downloaded from www.seafoodwatch.org. The program s goals are to raise awareness of important ocean conservation issues and empower seafood consumers and businesses to make choices for healthy oceans. Each sustainability recommendation on the regional pocket guides is supported by a Seafood Report. Each report synthesizes and analyzes the most current ecological, fisheries and ecosystem science on a species, then evaluates this information against the program s conservation ethic to arrive at a recommendation of Best Choices, Good Alternatives or Avoid. The detailed evaluation methodology is available upon request. In producing the Seafood Reports, Seafood Watch seeks out research published in academic, peer-reviewed journals whenever possible. Other sources of information include government technical publications, fishery management plans and supporting documents, and other scientific reviews of ecological sustainability. Seafood Watch Research Analysts also communicate regularly with ecologists, fisheries and aquaculture scientists, and members of industry and conservation organizations when evaluating fisheries and aquaculture practices. Capture fisheries and aquaculture practices are highly dynamic; as the scientific information on each species changes, Seafood Watch s sustainability recommendations and the underlying Seafood Reports will be updated to reflect these changes. Parties interested in capture fisheries, aquaculture practices and the sustainability of ocean ecosystems are welcome to use Seafood Reports in any way they find useful. For more information about Seafood Watch and Seafood Reports, please contact the Seafood Watch program at Monterey Bay Aquarium by calling 1-877-229-9990.
3 Guiding Principles Seafood Watch defines sustainable seafood as originating from sources, whether fished 1 or farmed, that can maintain or increase production in the long-term without jeopardizing the structure or function of affected ecosystems. Based on this principle, Seafood Watch had developed four sustainability criteria for evaluating wildcatch fisheries for consumers and businesses. These criteria are: How does fishing affect the species under assessment? How does the fishing affect other, target and non-target species? How effective is the fishery s management? How does the fishing affect habitats and the stability of the ecosystem? Each criterion includes: Factors to evaluate and score Guidelines for integrating these factors to produce a numerical score and rating Once a rating has been assigned to each criterion, we develop an overall recommendation. Criteria ratings and the overall recommendation are color-coded to correspond to the categories on the Seafood Watch pocket guide and online guide: Best Choice/Green: Are well managed and caught in ways that cause little harm to habitats or other wildlife. Good Alternative/Yellow: Buy, but be aware there are concerns with how they re caught. Avoid/Red: Take a pass on these for now. These items are overfished or caught in ways that harm other marine life or the environment. 1 Fish is used throughout this document to refer to finfish, shellfish and other invertebrates.
4 Summary This report focuses on the associated and unassociated purse seine fisheries in the Atlantic Ocean. The target species for these reports are albacore (Thunnus alalunga), blackfin (Thunnus atlanticus), bigeye (Thunnus obesus), skipjack (Katsuwonus pelamis), and yellowfin (Thunnus albacares) tuna. Albacore tuna in both the North and South Atlantic are currently overfished, and are undergoing overfishing in the South Atlantic. There is some uncertainty surrounding the current status of yellowfin tuna populations in the Atlantic, but there is some indication that they are overfished and unsustainably fished. Bigeye tuna populations are fluctuating around healthy levels but have been below these levels in recent years, while skipjack tuna populations appear to be healthy. The status of blackfin tuna populations is unclear. The International Commission for the Conservation of Atlantic Tunas (ICCAT) manages these species in the Atlantic Ocean. Management measures are in place for most of these species, and there are some measures specific to purse seine gears in place as well. Purse seine gears typically have little contact with bottom habitats, although fish aggregating devices (FADs) can be anchored to the bottom. However, the incidental capture of ecologically important species may be a concern, particularly in the associated fishery. Table of Conservation s and Overall Recommendations Stock / Fishery Bigeye tuna Atlantic - Purse Seine, Unassociated Yellowfin tuna Atlantic - Purse Seine, Unassociated Skipjack tuna Atlantic - Purse Seine, Unassociated Bigeye tuna Atlantic - Purse Seine, Floating object Skipjack tuna Atlantic - Purse Seine, Floating object Yellowfin tuna Atlantic - Purse Seine, Floating object Impacts on the Stock Yellow (2.64) Impacts on other Spp. Red (1.92) Management Habitat and Overall Ecosystem Recommendation Yellow (3.00) Green (3.87) Good Alternative (2.770) Red (2.16) Red (1.92) Yellow (3.00) Green (3.87) Avoid (2.633) Green (3.83) Red (1.92) Yellow (2.64) Yellow (3.00) Green (3.87) Good Alternative (3.039) Red (1.00) Red (1.73) Red (2.00) Avoid (1.740) Green (3.83) Red (1.00) Red (1.73) Red (2.00) Avoid (1.909) Red (2.16) Red (1.00) Red (1.73) Red (2.00) Avoid (1.654)
5 Albacore tuna Atlantic - Purse Seine, Floating object Albacore tuna Atlantic - Purse Seine, Unassociated Blackfin tuna Atlantic - Purse Seine, Floating object Albacore tuna South Atlantic - Purse Seine, Floating object Albacore tuna South Atlantic - Purse Seine, Unassociated Yellow (3.16) Yellow (3.16) Yellow (2.64) Red (1.00) Red (1.73) Red (2.00) Avoid (1.819) Red (1.92) Yellow (3.00) Green (3.87) Good Alternative (2.897) Red (1.00) Red (1.73) Red (2.00) Avoid (1.740) Red (1.41) Red (1.00) Red (1.73) Red (2.00) Avoid (1.488) Red (1.41) Red (1.92) Yellow (3.00) Green (3.87) Avoid (2.369) Scoring Guide Scores range from zero to five where zero indicates very poor performance and five indicates the fishing operations have no significant impact. Final Score = geometric mean of the four Scores (Criterion 1, Criterion 2, Criterion 3, Criterion 4). Best Choice/Green = Final Score >3.2, and no Red Criteria, and no Critical scores Good Alternative/Yellow = Final score >2.2, and neither Harvest Strategy (Factor 3.1) nor Bycatch Management Strategy (Factor 3.2) are Very High, 2 and no more than one Red Criterion, and no Critical scores, and does not meet the criteria for Best Choice (above) Avoid/Red = Final Score <=2.2, or either Harvest Strategy (Factor 3.1) or Bycatch Management Strategy (Factor 3.2) is Very High, 2 or two or more Red Criteria, or one or more Critical scores. 2 Because effective management is an essential component of sustainable fisheries, Seafood Watch issues an Avoid recommendation for any fishery scored as a Very High for either factor under Management (Criterion 3).
6 Table of Contents About Seafood Watch... 2 Guiding Principles... 3 Introduction... 7 Assessment... 13 Criterion 1: Stock for which you want a recommendation... 13 Criterion 2: Impacts on Other Species... 28 Criterion 3: Management effectiveness... 63 Criterion 4: Impacts on the habitat and ecosystem... 79 Acknowledgements... 85 References... 86
7 Introduction Scope of the analysis and ensuing recommendation This report focuses on the associated and unassociated purse seine fisheries in the Atlantic Ocean for albacore (Thunnus alalunga), blackfin (Thunnus atlanticus), bigeye (Thunnus obesus), skipjack (Katsuwonus pelamis) and yellowfin (Thunnus albacares) tuna. Overview of the species and management bodies Albacore tuna is widely distributed in temperate and tropical waters in all oceans, including the Atlantic and the Mediterranean Sea. There are two populations in the Atlantic, North and South, and a third in the Mediterranean. These populations have been identified for management purposes. Biological information supports classifying these as separate populations, but also suggests that there are subpopulations within the North Atlantic and Mediterranean and that intermingling may occur between populations in the Indian Ocean and South Atlantic. It is suspected that environmental changes may affect albacore populations (ICCAT 2012a). Blackfin tuna are only found in the Western Atlantic in pelagic waters from Massachusetts south to Trinidad and Brazil. Blackfin tuna are known to form mixed schools with skipjack tuna. Spawning seems to occur in offshore waters (Froese and Pauly 2013). Bigeye, skipjack, and yellowfin tuna are found in tropical and subtropical waters of the Atlantic and Mediterranean (except for bigeye tuna) (ICCAT 2012a). There are four populations of bigeye and yellowfin and five of skipjack: Western and Central Pacific Ocean, Eastern Pacific Ocean, Atlantic Ocean (Eastern and Western for skipjack), and Indian Ocean. Juvenile yellowfin tuna and juvenile bigeye tuna tend to form schools with skipjack tuna that are mostly found in surface waters. Larger tunas are found in subsurface waters where they also form schools (ICCAT 2012a). Globally, longlines are the most common fishing gear used to capture bigeye tuna, while purse seines capture the majority of skipjack and yellowfin tuna (ISSF 2013b). All five species are managed by the International Commission for the Conservation of Atlantic Tunas (ICCAT) in international waters of the Atlantic Ocean. Production Statistics Purse seine fisheries catch a very small proportion of albacore tuna in the Atlantic Ocean. For example, the total amount of albacore caught by purse seines in the North Atlantic has ranged from 5 t to 348 t since 2000, and in the South Atlantic catches have ranged from 2 t to 437 t. Total catches of albacore tuna in the North Atlantic were 20,948 t in 2013 and 19,148 t in the South Atlantic during 2013 (ICCAT 2014).
8 Figure 1. Albacore catches in the North Atlantic between 1950 and 2013 [ICCAT 2014]. Blackfin tuna catches (all gears combined) peaked during the mid-1990s at 4,488 t, and since 2003, catches have been below 2,000 t. The U.S. has reported between 200 t and 600 t since 1993 (ICCAT 2014). Figure 2. Blackfin tuna catches in the Atlantic Ocean between 1950 and 2013 [ICCAT 2014]. Bigeye tuna are principally caught by longlines but also purse seines and bait boat fisheries in the Atlantic Ocean. Bigeye tuna tend to be secondary target species in purse seine fisheries and are
9 primarily caught on floating object and fish aggregating device (FAD) sets. Purse seine catches in 2013 were 22,868 t, although unreported purse seine catches are large, as much as 20,000 t for bigeye, skipjack, and yellowfin tuna combined. Peak catches of bigeye tuna occurred in 2001 (100,000 t) and catches have been declining since, to 63,066 t in 2013 (ICCAT 2014). In the Eastern Atlantic, purse seines by far obtain the majority of the skipjack tuna catch. In the Western Atlantic, bait boats catch the majority; this fishery catches the second-highest amount of skipjack in the Eastern Atlantic. Purse seine catches in the Eastern Atlantic were 167,011 t in 2013 and 4,946 t in the Western Atlantic during 2013. Total catches of skipjack tuna in the Atlantic during 2013 were 221,628 t (ICCAT 2014). Figure 3. Skipjack tuna catches in the Atlantic Ocean between 1950 and 2013 [ICCAT 2014]. The primary gears used to capture yellowfin tuna in the Atlantic are purse seines in the Eastern Atlantic and longlines in the Western Atlantic. Bait boat fisheries are also significant in the Eastern Atlantic. By 2007, catches of yellowfin tuna throughout the Atlantic had declined by nearly 50%, from 194,000 t in 1990 to 100,000 t. In recent years, catches have begun to increase. Purse seine catches in particular declined 60% in the Eastern Atlantic between 1990 and 2007 and 90% in the Western Atlantic between 1994 and 2009. Similar to Atlantic-wide catches, purse seine catches have since increased. In the Eastern Atlantic, purse seine catches were 58,014 t in 2013 and 7,903 t in the Western Atlantic during 2014 (ICCAT 2014).
10 Figure 4. Yellowfin tuna catches in the Atlantic Ocean between 1950 and 2013 [ICCAT 2014]. Importance to the U.S./North American market The majority of albacore imported from the ICCAT Convention area by the United States came from Canada (57%), followed by Mexico (22%) (NMFS 2014). Figure 5. Major contributors to U.S. albacore tuna imports (%), ICCAT Convention Area (country of origin) [NMFS 2013].
11 Bigeye tuna were primarily imported from South Korea (32%), followed by Brazil (24%), in 2013 (NMFS 2014). Figure 6. Major contributors to U.S. bigeye tuna imports (%), ICCAT Convention Area (country of origin) [NMFS 2014]. Skipjack tuna imports dropped from 24,128 t in 2011 to 17,635 in 2012. Nearly all (84%) of the skipjack tuna imported by the United States during 2012 came from Mexico (84%). Figure 7. Major contributors to U.S. skipjack tuna imports (%), ICCAT Convention Area (country of origin) [NMFS 2014].
12 During 2013, yellowfin tuna were primarily imported from the Philippines (24%), followed by Trinidad and Tobago (18%) (NFMS 2014). Figure 8. Major contributors to U.S. yellowfin tuna imports (%), ICCAT Convention Area (country of origin) [NMFS 2014]. Common and market names Albacore tuna is also known as germon, longfinned tuna, albecore, and T. germo. Skipjack tuna are also known as ocean bonito and lesser tuna. In Hawaii, bigeye and yellowfin tuna are known as Ahi, and skipjack is known as Aku. Blackfin tuna does not have any other accepted names. Primary product forms These species are sold fresh and frozen and for the sashimi and sushi market.
13 Assessment This section assesses the sustainability of the fishery(s) relative to the Seafood Watch Criteria for Fisheries, available at http://www.seafoodwatch.org. Criterion 1: Stock for which you want a recommendation This criterion evaluates the impact of fishing mortality on the species, given its current abundance. The inherent vulnerability to fishing rating influences how abundance is scored, when abundance is unknown. The final Criterion 1 score is determined by taking the geometric mean of the abundance and fishing mortality scores. The Criterion 1 rating is determined as follows: Score >3.2=Green or Low Score >2.2 and <=3.2=Yellow or Score <=2.2=Red or High Rating is Critical if Factor 1.3 (Fishing Mortality) is Critical. Criterion 1 Summary ALBACORE TUNA Region / Method Atlantic Purse Seine, Floating object Atlantic Purse Seine, Unassociated South Atlantic Purse Seine, Floating object South Atlantic Purse Seine, Unassociated Inherent Stock Status Vulnerability 2.00:Medium 2.00:High 2.00:Medium 2.00:High 2.00:Medium 2.00:High 2.00:Medium 2.00:High Fishing Subscore Mortality 5.00:Very Low Yellow (3.162) 5.00:Very Low Yellow (3.162) 1.00:High Red (1.414) 1.00:High Red (1.414) BIGEYE TUNA Region / Method Atlantic Purse Seine, Floating object Atlantic Purse Seine, Unassociated Inherent Vulnerability Stock Status Fishing Mortality Subscore 2.00:Medium 3.00: 2.33: Yellow (2.644) 2.00:Medium 3.00: 2.33: Yellow (2.644) BLACKFIN TUNA Region / Method Inherent Vulnerability Stock Status Fishing Mortality Subscore
14 Atlantic Purse Seine, Floating object 2.00:Medium 3.00: 2.33: Yellow (2.644) SKIPJACK TUNA Region / Method Atlantic Purse Seine, Floating object Atlantic Purse Seine, Unassociated Inherent Stock Status Vulnerability 2.00:Medium 4.00:Low 2.00:Medium 4.00:Low Fishing Mortality 3.67:Low 3.67:Low Subscore Green (3.831) Green (3.831) YELLOWFIN TUNA Region / Method Atlantic Purse Seine, Floating object Atlantic Purse Seine, Unassociated Inherent Stock Status Vulnerability 2.00:Medium 2.00:High 2.00:Medium 2.00:High Fishing Subscore Mortality 2.33: Red (2.159) 2.33: Red (2.159) Albacore tuna in both the south and north Atlantic Ocean are currently overfished and are undergoing overfishing in the south but not north Atlantic. There is some uncertainty surrounding the current status of yellowfin tuna populations in the Atlantic, but there is some indication that they may be close to overfished and unsustainably fished. Bigeye tuna populations are fluctuating around healthy levels but have been below these levels in recent years. However, skipjack tuna populations appear to be healthy. The status of blackfin tuna populations is unclear. Criterion 1 Assessment ALBACORE TUNA Factor 1.1 - Inherent Vulnerability Scoring Guidelines Low The FishBase vulnerability score for species is 0-35, OR species exhibits life history characteristics that make it resilient to fishing, (e.g., early maturing ( Medium The FishBase vulnerability score for species is 36-55, OR species exhibits life history characteristics that make it neither particularly vulnerable nor resilient to fishing, (e.g., moderate age at sexual maturity (5-15 years), moderate maximum age (10-25 years), moderate maximum size, and middle of food chain).
15 High The FishBase vulnerability score for species is 56-100, OR species exhibits life history characteristics that make is particularly vulnerable to fishing, (e.g., long-lived (>25 years), late maturing (>15 years), low reproduction rate, large body size, and top-predator). Note: The FishBase vulnerability scores is an index of the inherent vulnerability of marine fishes to fishing based on life history parameters: maximum length, age at first maturity, longevity, growth rate, natural mortality rate, fecundity, spatial behaviors (e.g., schooling, aggregating for breeding, or consistently returning to the same sites for feeding or reproduction) and geographic range. Atlantic, Purse Seine, Unassociated South Atlantic, Purse Seine, Unassociated Medium FishBase assigned a high vulnerability score of 58 out of 100 (Froese and Pauly 2013). However, the lifehistory characteristics of albacore suggest only a medium vulnerability to fishing. For example, albacore reach sexual maturity between 5 and 6 years of age and reach a maximum age of 15 years (ISCAWG 2011). They are broadcast spawners and top predators (Froese and Pauly 2013). These life history characteristics result in a medium vulnerability. Factor 1.2 - Stock Status Scoring Guidelines 5 (Very Low ) Strong evidence exists that the population is above target abundance level (e.g., biomass at maximum sustainable yield, BMSY) or near virgin biomass. 4 (Low ) Population may be below target abundance level, but it is considered not overfished 3 ( ) Abundance level is unknown and the species has a low or medium inherent vulnerability to fishing. 2 (High ) Population is overfished, depleted, or a species of concern, OR abundance is unknown and the species has a high inherent vulnerability to fishing. 1 (Very High ) Population is listed as threatened or endangered. Atlantic, Purse Seine, Unassociated
16 High The population of albacore tuna in the North Atlantic has been below the level needed to produce the maximum sustainable yield (B MSY ) since the mid-1980s, but has improved from the lowest levels in the late 1990s. There is considerable uncertainty surrounding the status of albacore tuna in the North Atlantic, as evidenced by the wide array of model results. However, the ratio of the current spawning stock biomass to the maximum sustainable yield (SSB current /SSB MSY ) is estimated to be 0.94 (0.74 1.14). There is a 0.2% probability that the population is overfished and undergoing overfishing; a 27.4% probability that the population is neither overfished nor undergoing overfishing; and a 72.4% probability that the population is either overfished or that overfishing is occurring, but not both (ICCAT 20013). So this results in a high concern score. South Atlantic, Purse Seine, Unassociated High The 2013 assessment of albacore tuna in the South Atlantic provided a wide range of results. Based on all scenarios included in the assessment, there is a 57% probability that the population of albacore tuna is overfished and undergoing overfishing; a 13% probability that the population is overfished or undergoing overfishing, but not both; and a 30% probability that the biomass is above and that fishing mortality is below Convention objectives (ICCAT 2013a). The ratio of the current biomass to one that would produce the maximum sustainable yield (B/B MSY ) is 0.92 (0.71 1.26). Because both populations are overfished, this is scored as high concern. Factor 1.3 - Fishing Mortality Scoring Guidelines 5 (Very Low ) Highly likely that fishing mortality is below a sustainable level (e.g., below fishing mortality at maximum sustainable yield, FMSY), OR fishery does not target species and its contribution to the mortality of species is negligible ( 5% of a sustainable level of fishing mortality). 3.67 (Low ) Probable (>50%) chance that fishing mortality is at or below a sustainable level, but some uncertainty exists, OR fishery does not target species and does not adversely affect species, but its contribution to mortality is not negligible, OR fishing mortality is unknown, but the population is healthy and the species has a low susceptibility to the fishery (low chance of being caught).
17 2.33 ( ) Fishing mortality is fluctuating around sustainable levels, OR fishing mortality is unknown and species has a moderate-high susceptibility to the fishery and, if species is depleted, reasonable management is in place. 1 (High ) Overfishing is occurring, but management is in place to curtail overfishing, OR fishing mortality is unknown, species is depleted, and no management is in place. 0 (Critical) Overfishing is known to be occurring and no reasonable management is in place to curtail overfishing. Atlantic, Purse Seine, Unassociated Very Low The maximum sustainable yield (MSY) of albacore tuna in the North Atlantic is estimated to be 31,680 t. Fishing mortality rates from the 1960s to mid-2000s were above the levels needed to produce the maximum sustainable yield (F MSY ). But F 2012 /F MSY = 0.72 (0.55 0.89) and the population is no longer undergoing overfishing (ICCAT 2013a), so it is scored as very low concern. South Atlantic, Purse Seine, Unassociated High According to the last assessment (2013) conducted for the South Atlantic population, the median maximum sustainable yield (MSY) value was 25,228 t (19,109 28,360 t) in 2012, and the median ratio of current fishing mortality rates to those that produce the maximum sustainable yield (F/F MSY ) was 1.04 (0.38 1.32). The status is difficult to determine from this large degree of uncertainty, but it is likely that overfishing is occurring, with a 57% chance that the population is overfished and that overfishing is occurring (ICCAT 2013a). There are management measures in place but they have failed to maintain the population, so it is scored as high concern. BIGEYE TUNA Factor 1.1 - Inherent Vulnerability Scoring Guidelines Low The FishBase vulnerability score for species is 0-35, OR species exhibits life history characteristics that make it resilient to fishing, (e.g., early maturing (
18 Medium The FishBase vulnerability score for species is 36-55, OR species exhibits life history characteristics that make it neither particularly vulnerable nor resilient to fishing, (e.g., moderate age at sexual maturity (5-15 years), moderate maximum age (10-25 years), moderate maximum size, and middle of food chain). High The FishBase vulnerability score for species is 56-100, OR species exhibits life history characteristics that make is particularly vulnerable to fishing, (e.g., long-lived (>25 years), late maturing (>15 years), low reproduction rate, large body size, and top-predator). Note: The FishBase vulnerability scores is an index of the inherent vulnerability of marine fishes to fishing based on life history parameters: maximum length, age at first maturity, longevity, growth rate, natural mortality rate, fecundity, spatial behaviors (e.g., schooling, aggregating for breeding, or consistently returning to the same sites for feeding or reproduction) and geographic range. Atlantic, Purse Seine, Unassociated Medium FishBase assigned a high to very high vulnerability of 72 out of 100 (Froese and Pauly 2013). However, bigeye tuna s life-history characteristics suggest a medium vulnerability to fishing. For example, bigeye tuna reach sexual maturity around the time they reach a size of 100 125 cm; they reach a maximum size of 200 cm and live around 11 years (Davies et al. 2011) (Froese et al. 2013). They are broadcast spawners and top predators (Froese and Pauly 2013). These life-history characteristics result in a medium vulnerability. Factor 1.2 - Stock Status Scoring Guidelines 5 (Very Low ) Strong evidence exists that the population is above target abundance level (e.g., biomass at maximum sustainable yield, BMSY) or near virgin biomass. 4 (Low ) Population may be below target abundance level, but it is considered not overfished 3 ( ) Abundance level is unknown and the species has a low or medium inherent vulnerability to fishing. 2 (High ) Population is overfished, depleted, or a species of concern, OR abundance is unknown and the species has a high inherent vulnerability to fishing. 1 (Very High ) Population is listed as threatened or endangered.
19 Atlantic, Purse Seine, Unassociated Bigeye tuna in the Atlantic was last assessed in 2010. Large declines in abundance occurred during the mid-1990s, but over the past 5 to 6 years, abundance appears to have increased. In 2010, the biomass was estimated between 72% and 134% of the biomass at maximum sustainable levels (B MSY ) (median = 101%), whereas median estimates of B/B MSY from the late 1990s to 2008/09 were below 1. The 2010 assessment contained uncertainty surrounding the best method to represent the dynamics of the stock, and the indices of abundance and the calculation of model inputs were very large in this assessment (ICCAT 2010a). Because the biomass is fluctuating around B MSY and bigeye tuna has a moderate vulnerability to fishing, this factor is scored as moderate concern. Factor 1.3 - Fishing Mortality Scoring Guidelines 5 (Very Low ) Highly likely that fishing mortality is below a sustainable level (e.g., below fishing mortality at maximum sustainable yield, FMSY), OR fishery does not target species and its contribution to the mortality of species is negligible ( 5% of a sustainable level of fishing mortality). 3.67 (Low ) Probable (>50%) chance that fishing mortality is at or below a sustainable level, but some uncertainty exists, OR fishery does not target species and does not adversely affect species, but its contribution to mortality is not negligible, OR fishing mortality is unknown, but the population is healthy and the species has a low susceptibility to the fishery (low chance of being caught). 2.33 ( ) Fishing mortality is fluctuating around sustainable levels, OR fishing mortality is unknown and species has a moderate-high susceptibility to the fishery and, if species is depleted, reasonable management is in place. 1 (High ) Overfishing is occurring, but management is in place to curtail overfishing, OR fishing mortality is unknown, species is depleted, and no management is in place. 0 (Critical) Overfishing is known to be occurring and no reasonable management is in place to curtail overfishing. Atlantic, Purse Seine, Unassociated Bigeye tuna in the Atlantic were last assessed in 2010. The maximum sustainable yield (MSY) was
20 estimated between 78,700 t and 101,600 t, with a median value of 92,000 t. Fishing mortality has historically been high, particularly during the mid-1990s when fishing mortality was higher than F MSY. In recent years, fishing mortality rates have declined; currently, they are estimated between 65% and 155% of F MSY, with the median value at 95% (ICCAT 2010a). Because F appears to be fluctuating around F MSY, this is scored as moderate concern. BLACKFIN TUNA Factor 1.1 - Inherent Vulnerability Scoring Guidelines Low The FishBase vulnerability score for species is 0-35, OR species exhibits life history characteristics that make it resilient to fishing, (e.g., early maturing ( Medium The FishBase vulnerability score for species is 36-55, OR species exhibits life history characteristics that make it neither particularly vulnerable nor resilient to fishing, (e.g., moderate age at sexual maturity (5-15 years), moderate maximum age (10-25 years), moderate maximum size, and middle of food chain). High The FishBase vulnerability score for species is 56-100, OR species exhibits life history characteristics that make is particularly vulnerable to fishing, (e.g., long-lived (>25 years), late maturing (>15 years), low reproduction rate, large body size, and top-predator). Note: The FishBase vulnerability scores is an index of the inherent vulnerability of marine fishes to fishing based on life history parameters: maximum length, age at first maturity, longevity, growth rate, natural mortality rate, fecundity, spatial behaviors (e.g., schooling, aggregating for breeding, or consistently returning to the same sites for feeding or reproduction) and geographic range. Medium FishBase assigned a moderate vulnerability score of 41 out of 100 (Froese and Pauly 2013). Blackfin tuna is a small tuna species that reaches sexual maturity by 50 cm length and 3 years of age. The maximum length attained is around 108 cm and they live to around 5 years. Blackfin tuna are broadcast spawners and high-level predators in the ecosystem (Froese and Pauly 2014). These life-history characteristics also suggest a medium vulnerability.
21 Factor 1.2 - Stock Status Scoring Guidelines 5 (Very Low ) Strong evidence exists that the population is above target abundance level (e.g., biomass at maximum sustainable yield, BMSY) or near virgin biomass. 4 (Low ) Population may be below target abundance level, but it is considered not overfished 3 ( ) Abundance level is unknown and the species has a low or medium inherent vulnerability to fishing. 2 (High ) Population is overfished, depleted, or a species of concern, OR abundance is unknown and the species has a high inherent vulnerability to fishing. 1 (Very High ) Population is listed as threatened or endangered. In Atlantic waters, blackfin tuna are assessed along with 13 other small tuna species. Currently, there is not enough information to conduct a full assessment of this group (ICCAT 2012a). According to the International Union for Conservation of Nature (IUCN), blackfin tuna is a species of Least, with a stable population trend, and is considered one of the most common tuna species in the western Atlantic (Collette et al. 2011a). This is scored as moderate concern because information on their status is unknown and they have a moderate vulnerability to fishing pressure. Factor 1.3 - Fishing Mortality Scoring Guidelines 5 (Very Low ) Highly likely that fishing mortality is below a sustainable level (e.g., below fishing mortality at maximum sustainable yield, FMSY), OR fishery does not target species and its contribution to the mortality of species is negligible ( 5% of a sustainable level of fishing mortality). 3.67 (Low ) Probable (>50%) chance that fishing mortality is at or below a sustainable level, but some uncertainty exists, OR fishery does not target species and does not adversely affect species, but its contribution to mortality is not negligible, OR fishing mortality is unknown, but the population is healthy and the species has a low susceptibility to the fishery (low chance of being caught). 2.33 ( ) Fishing mortality is fluctuating around sustainable levels, OR fishing mortality is unknown and species has a moderate-high susceptibility to the fishery and, if species is depleted, reasonable management is in place.
22 1 (High ) Overfishing is occurring, but management is in place to curtail overfishing, OR fishing mortality is unknown, species is depleted, and no management is in place. 0 (Critical) Overfishing is known to be occurring and no reasonable management is in place to curtail overfishing. Blackfin tuna makes up a small proportion of small tuna catches in the Atlantic Ocean. No assessment has been conducted due to a lack of data. Landings have been variable over the years, peaking in the early 1990s but showing no consistent trend over time (ICCAT 2012a). They are caught by a variety of gears but there is no indication that overfishing is occurring (Collette et al. 2011a). Because information on fishing mortality is not available, this is scored as moderate concern. SKIPJACK TUNA Factor 1.1 - Inherent Vulnerability Scoring Guidelines Low The FishBase vulnerability score for species is 0-35, OR species exhibits life history characteristics that make it resilient to fishing, (e.g., early maturing ( Medium The FishBase vulnerability score for species is 36-55, OR species exhibits life history characteristics that make it neither particularly vulnerable nor resilient to fishing, (e.g., moderate age at sexual maturity (5-15 years), moderate maximum age (10-25 years), moderate maximum size, and middle of food chain). High The FishBase vulnerability score for species is 56-100, OR species exhibits life history characteristics that make is particularly vulnerable to fishing, (e.g., long-lived (>25 years), late maturing (>15 years), low reproduction rate, large body size, and top-predator). Note: The FishBase vulnerability scores is an index of the inherent vulnerability of marine fishes to fishing based on life history parameters: maximum length, age at first maturity, longevity, growth rate, natural mortality rate, fecundity, spatial behaviors (e.g., schooling, aggregating for breeding, or consistently returning to the same sites for feeding or reproduction) and geographic range. Atlantic, Purse Seine, Unassociated
23 Medium FishBase assigned a moderate vulnerability score of 39 out of 100 (Froese and Pauly 2013). Skipjack lifehistory characteristics support this score. Sexual maturity is reached around 45 cm length or 2 years old, and they can reach a maximum size of 110 cm and age of 12 years. They are broadcast spawners and have a high trophic level (Froese and Pauly 2013). Factor 1.2 - Stock Status Scoring Guidelines 5 (Very Low ) Strong evidence exists that the population is above target abundance level (e.g., biomass at maximum sustainable yield, BMSY) or near virgin biomass. 4 (Low ) Population may be below target abundance level, but it is considered not overfished 3 ( ) Abundance level is unknown and the species has a low or medium inherent vulnerability to fishing. 2 (High ) Population is overfished, depleted, or a species of concern, OR abundance is unknown and the species has a high inherent vulnerability to fishing. 1 (Very High ) Population is listed as threatened or endangered. Atlantic, Purse Seine, Unassociated Low Stock assessments for skipjack tuna are difficult to employ due to its biology and fishery characteristics. In the Atlantic Ocean, eastern and western stocks of skipjack tuna are assessed. According to the most recent assessment conducted in 2014, the biomass in the eastern region is likely above target levels (biomass needed to produce the maximum sustainable yield, B MSY ) and the biomass in the western region is probably 30% above the level needed to produce the maximum sustainable yield (B 2013 /B MSY = 1.3). Both populations are not overfished (ICCAT 2014). The high level of uncertainty associated with this assessment precludes a score of very low concern, so this factor rates as low concern. Factor 1.3 - Fishing Mortality Scoring Guidelines 5 (Very Low ) Highly likely that fishing mortality is below a sustainable level (e.g., below fishing mortality at maximum sustainable yield, FMSY), OR fishery does not target
24 species and its contribution to the mortality of species is negligible ( 5% of a sustainable level of fishing mortality). 3.67 (Low ) Probable (>50%) chance that fishing mortality is at or below a sustainable level, but some uncertainty exists, OR fishery does not target species and does not adversely affect species, but its contribution to mortality is not negligible, OR fishing mortality is unknown, but the population is healthy and the species has a low susceptibility to the fishery (low chance of being caught). 2.33 ( ) Fishing mortality is fluctuating around sustainable levels, OR fishing mortality is unknown and species has a moderate-high susceptibility to the fishery and, if species is depleted, reasonable management is in place. 1 (High ) Overfishing is occurring, but management is in place to curtail overfishing, OR fishing mortality is unknown, species is depleted, and no management is in place. 0 (Critical) Overfishing is known to be occurring and no reasonable management is in place to curtail overfishing. Atlantic, Purse Seine, Unassociated Low Stock assessments for skipjack tuna are difficult to conduct based on their life history and the fishery characteristics. The last assessment in the Atlantic was conducted in 2014 for eastern and western populations. The assessment determined that the fishing mortality rate (F 2013 ) in the Eastern Atlantic was likely below the level needed to produce the maximum sustainable yield (F MSY ), and the rate in the Western Atlantic was likely 30% below F MSY (F 2013 /F MSY = 0.70) (ICCAT 2014). Because the populations appear to be sustainably fished but there is some uncertainty surrounding the results, this factor scores as low concern rather than very low concern. YELLOWFIN TUNA Factor 1.1 - Inherent Vulnerability Scoring Guidelines Low The FishBase vulnerability score for species is 0-35, OR species exhibits life history characteristics that make it resilient to fishing, (e.g., early maturing ( Medium The FishBase vulnerability score for species is 36-55, OR species exhibits life history characteristics that make it neither particularly vulnerable nor resilient to fishing,
25 (e.g., moderate age at sexual maturity (5-15 years), moderate maximum age (10-25 years), moderate maximum size, and middle of food chain). High The FishBase vulnerability score for species is 56-100, OR species exhibits life history characteristics that make is particularly vulnerable to fishing, (e.g., long-lived (>25 years), late maturing (>15 years), low reproduction rate, large body size, and top-predator). Note: The FishBase vulnerability scores is an index of the inherent vulnerability of marine fishes to fishing based on life history parameters: maximum length, age at first maturity, longevity, growth rate, natural mortality rate, fecundity, spatial behaviors (e.g., schooling, aggregating for breeding, or consistently returning to the same sites for feeding or reproduction) and geographic range. Atlantic, Purse Seine, Unassociated Medium FishBase assigned a moderate vulnerability score of 46 out of 100 (Froese and Pauly 2013). Yellowfin tuna reaches sexual maturity around 100 cm in length and 2 5 years of age. A maximum length of 140 150 cm can be attained and they can live 8 9 years. They are broadcast spawners and high-level predators in the ecosystem (Froese and Pauly 2014) (ICCAT 2014). These life-history characteristics also support a medium level of vulnerability. Factor 1.2 - Stock Status Scoring Guidelines 5 (Very Low ) Strong evidence exists that the population is above target abundance level (e.g., biomass at maximum sustainable yield, BMSY) or near virgin biomass. 4 (Low ) Population may be below target abundance level, but it is considered not overfished 3 ( ) Abundance level is unknown and the species has a low or medium inherent vulnerability to fishing. 2 (High ) Population is overfished, depleted, or a species of concern, OR abundance is unknown and the species has a high inherent vulnerability to fishing. 1 (Very High ) Population is listed as threatened or endangered. Atlantic, Purse Seine, Unassociated
26 High Yellowfin tuna in the Atlantic Ocean was last assessed in 2011. There was some degree of uncertainty with the two models, which indicated opposite results (i.e., one showed an increasing abundance trend and the other showed a decreasing trend). The population is currently estimated to be 15% below Convention objectives (B 2010 /B MSY = 0.85 (0.61 1.12)) and therefore overfished (ICCAT 2011d). This rates as high concern because the population is considered overfished. Factor 1.3 - Fishing Mortality Scoring Guidelines 5 (Very Low ) Highly likely that fishing mortality is below a sustainable level (e.g., below fishing mortality at maximum sustainable yield, FMSY), OR fishery does not target species and its contribution to the mortality of species is negligible ( 5% of a sustainable level of fishing mortality). 3.67 (Low ) Probable (>50%) chance that fishing mortality is at or below a sustainable level, but some uncertainty exists, OR fishery does not target species and does not adversely affect species, but its contribution to mortality is not negligible, OR fishing mortality is unknown, but the population is healthy and the species has a low susceptibility to the fishery (low chance of being caught). 2.33 ( ) Fishing mortality is fluctuating around sustainable levels, OR fishing mortality is unknown and species has a moderate-high susceptibility to the fishery and, if species is depleted, reasonable management is in place. 1 (High ) Overfishing is occurring, but management is in place to curtail overfishing, OR fishing mortality is unknown, species is depleted, and no management is in place. 0 (Critical) Overfishing is known to be occurring and no reasonable management is in place to curtail overfishing. Atlantic, Purse Seine, Unassociated The current fishing mortality rate is estimated to be 13% below F MSY (F current /F MSY = 0.87 (0.68 1.40)) and the maximum sustainable yield (MSY) is estimated at 144,600 t (ICCAT 2011d). This suggests that fishing mortality rates are sustainable. However, the assessment had some degree of uncertainty surrounding the results, with two models indicating opposite trends. One model estimated that fishing mortality rates were not sustainable, while the other estimated they were sustainable (ICCAT 2011d). In addition, the fishing mortality reference point used in the base case model (F max, the fishing level that produces
27 the largest yield per catch from the fishery) may not be suitable, because some studies have indicated that F max is likely greater than F MSY (Gabriel and Mace 1999). Therefore, if a more conservative reference points were used, it may have actually indicated that overfishing is occurring (ICCAT 2011k). This precludes a score of low concern and instead rates as moderate concern.
28 Criterion 2: Impacts on Other Species All main retained and bycatch species in the fishery are evaluated in the same way as the species under assessment were evaluated in Criterion 1. Seafood Watch defines bycatch as all fisheries-related mortality or injury to species other than the retained catch. Examples include discards, endangered or threatened species catch, and ghost fishing. To determine the final Criterion 2 score, the score for the lowest scoring retained/bycatch species is multiplied by the discard rate score (ranges from 0-1), which evaluates the amount of non-retained catch (discards) and bait use relative to the retained catch. The Criterion 2 rating is determined as follows: Score >3.2=Green or Low Score >2.2 and <=3.2=Yellow or Score <=2.2=Red or High Rating is Critical if Factor 2.3 (Fishing Mortality) is Critical. Criterion 2 Summary Albacore tuna: Subscore:: 1.000 Discard Rate: 1.00 C2 Rate: 1.000 Species Inherent Vulnerability Stock Status OCEANIC WHITETIP SHARK High 1.00: Very High BLUE MARLIN Medium 2.00: High SILKY SHARK High 2.00: High TURTLES High 1.00: Very High YELLOWFIN TUNA Medium 2.00: High BIGEYE TUNA Medium 3.00: BLACKFIN TUNA Medium 3.00: RAINBOW RUNNER Medium 3.00: TRIGGERFISH SPP. Medium 3.00: Fishing Mortality 1.00: High 1.00: High 1.00: High 3.67: Low 2.33: 2.33: 2.33: 2.33: 2.33: Subscore 1.000 1.414 1.414 1.916 2.159 2.644 2.644 2.644 2.644
29 ALBACORE TUNA Medium 2.00: High WAHOO Medium 3.00: DOLPHINFISH (MAHI MAHI) Medium 4.00: Low SKIPJACK TUNA Medium 4.00: Low 5.00: Very Low 3.67: Low 3.67: Low 3.67: Low 3.162 3.318 3.831 3.831 Albacore tuna: Atlantic, Purse Seine, Unassociated Subscore:: 1.916 Discard Rate: 1.00 C2 Rate: 1.916 Species Inherent Vulnerability Stock Status TURTLES High 1.00: Very High ATLANTIC SAILFISH Medium 2.00: High YELLOWFIN TUNA Medium 2.00: High BIGEYE TUNA Medium 3.00: ALBACORE TUNA Medium 2.00: High SKIPJACK TUNA Medium 4.00: Low Fishing Mortality 3.67: Low 2.33: 2.33: 2.33: 5.00: Very Low 3.67: Low Subscore 1.916 2.159 2.159 2.644 3.162 3.831 Albacore tuna: Subscore:: 1.000 Discard Rate: 1.00 C2 Rate: 1.000 Species Inherent Vulnerability Stock Status Fishing Mortality OCEANIC WHITETIP SHARK High 1.00: Very 1.00: High High ALBACORE TUNA Medium 2.00: High 1.00: High SILKY SHARK High 2.00: High 1.00: High TURTLES High 1.00: Very 3.67: Low High Subscore 1.000 1.414 1.414 1.916
30 YELLOWFIN TUNA Medium 2.00: High BIGEYE TUNA Medium 3.00: BLACKFIN TUNA Medium 3.00: RAINBOW RUNNER Medium 3.00: TRIGGERFISH SPP. Medium 3.00: BLUE MARLIN Medium 2.00: High WAHOO Medium 3.00: DOLPHINFISH (MAHI MAHI) Medium 4.00: Low SKIPJACK TUNA Medium 4.00: Low 2.33: 2.33: 2.33: 2.33: 2.33: 3.67: Low 3.67: Low 3.67: Low 3.67: Low 2.159 2.644 2.644 2.644 2.644 2.709 3.318 3.831 3.831 Albacore tuna: South Atlantic, Purse Seine, Unassociated Subscore:: 1.916 Discard Rate: 1.00 C2 Rate: 1.916 Species Inherent Vulnerability Stock Status ALBACORE TUNA Medium 2.00: High TURTLES High 1.00: Very High ATLANTIC SAILFISH Medium 2.00: High YELLOWFIN TUNA Medium 2.00: High BIGEYE TUNA Medium 3.00: SKIPJACK TUNA Medium 4.00: Low Fishing Mortality 1.00: High 3.67: Low 2.33: 2.33: 2.33: 3.67: Low Subscore 1.414 1.916 2.159 2.159 2.644 3.831
31 Bigeye tuna: Subscore:: 1.000 Discard Rate: 1.00 C2 Rate: 1.000 Species Inherent Vulnerability Stock Status OCEANIC WHITETIP SHARK High 1.00: Very High BLUE MARLIN Medium 2.00: High SILKY SHARK High 2.00: High TURTLES High 1.00: Very High YELLOWFIN TUNA Medium 2.00: High BIGEYE TUNA Medium 3.00: BLACKFIN TUNA Medium 3.00: RAINBOW RUNNER Medium 3.00: TRIGGERFISH SPP. Medium 3.00: ALBACORE TUNA Medium 2.00: High WAHOO Medium 3.00: DOLPHINFISH (MAHI MAHI) Medium 4.00: Low SKIPJACK TUNA Medium 4.00: Low Fishing Mortality 1.00: High 1.00: High 1.00: High 3.67: Low 2.33: 2.33: 2.33: 2.33: 2.33: 5.00: Very Low 3.67: Low 3.67: Low 3.67: Low Subscore 1.000 1.414 1.414 1.916 2.159 2.644 2.644 2.644 2.644 3.162 3.318 3.831 3.831 Bigeye tuna: Atlantic, Purse Seine, Unassociated Subscore:: 1.916 Discard Rate: 1.00 C2 Rate: 1.916 Species Inherent Stock Status Fishing Subscore Vulnerability Mortality TURTLES High 1.00: Very 3.67: Low 1.916
32 High ATLANTIC SAILFISH Medium 2.00: High 2.33: YELLOWFIN TUNA Medium 2.00: High BIGEYE TUNA Medium 3.00: ALBACORE TUNA Medium 2.00: High SKIPJACK TUNA Medium 4.00: Low 2.33: 2.33: 5.00: Very Low 3.67: Low 2.159 2.159 2.644 3.162 3.831 Blackfin tuna: Subscore:: 1.000 Discard Rate: 1.00 C2 Rate: 1.000 Species Inherent Vulnerability Stock Status Fishing Mortality OCEANIC WHITETIP SHARK High 1.00: Very 1.00: High High BLUE MARLIN Medium 2.00: High 1.00: High SILKY SHARK High 2.00: High 1.00: High TURTLES High 1.00: Very 3.67: Low High YELLOWFIN TUNA Medium 2.00: High 2.33: BIGEYE TUNA Medium 3.00: 2.33: BLACKFIN TUNA Medium 3.00: RAINBOW RUNNER Medium 3.00: TRIGGERFISH SPP. Medium 3.00: ALBACORE TUNA Medium 2.00: High 2.33: 2.33: 2.33: 5.00: Very Low Subscore 1.000 1.414 1.414 1.916 2.159 2.644 2.644 2.644 2.644 3.162 WAHOO Medium 3.00: 3.67: Low 3.318
33 DOLPHINFISH (MAHI MAHI) Medium 4.00: Low SKIPJACK TUNA Medium 4.00: Low 3.67: Low 3.67: Low 3.831 3.831 Skipjack tuna: Subscore:: 1.000 Discard Rate: 1.00 C2 Rate: 1.000 Species Inherent Vulnerability Stock Status OCEANIC WHITETIP SHARK High 1.00: Very High BLUE MARLIN Medium 2.00: High SILKY SHARK High 2.00: High TURTLES High 1.00: Very High YELLOWFIN TUNA Medium 2.00: High BIGEYE TUNA Medium 3.00: BLACKFIN TUNA Medium 3.00: RAINBOW RUNNER Medium 3.00: TRIGGERFISH SPP. Medium 3.00: ALBACORE TUNA Medium 2.00: High WAHOO Medium 3.00: DOLPHINFISH (MAHI MAHI) Medium 4.00: Low SKIPJACK TUNA Medium 4.00: Low Fishing Mortality 1.00: High 1.00: High 1.00: High 3.67: Low 2.33: 2.33: 2.33: 2.33: 2.33: 5.00: Very Low 3.67: Low 3.67: Low 3.67: Low Subscore 1.000 1.414 1.414 1.916 2.159 2.644 2.644 2.644 2.644 3.162 3.318 3.831 3.831
34 Skipjack tuna: Atlantic, Purse Seine, Unassociated Subscore:: 1.916 Discard Rate: 1.00 C2 Rate: 1.916 Species Inherent Vulnerability Stock Status TURTLES High 1.00: Very High ATLANTIC SAILFISH Medium 2.00: High YELLOWFIN TUNA Medium 2.00: High BIGEYE TUNA Medium 3.00: ALBACORE TUNA Medium 2.00: High SKIPJACK TUNA Medium 4.00: Low Fishing Mortality 3.67: Low 2.33: 2.33: 2.33: 5.00: Very Low 3.67: Low Subscore 1.916 2.159 2.159 2.644 3.162 3.831 Yellowfin tuna: Subscore:: 1.000 Discard Rate: 1.00 C2 Rate: 1.000 Species Inherent Vulnerability Stock Status OCEANIC WHITETIP SHARK High 1.00: Very High BLUE MARLIN Medium 2.00: High SILKY SHARK High 2.00: High TURTLES High 1.00: Very High YELLOWFIN TUNA Medium 2.00: High BIGEYE TUNA Medium 3.00: BLACKFIN TUNA Medium 3.00: RAINBOW RUNNER Medium 3.00: Fishing Mortality 1.00: High 1.00: High 1.00: High 3.67: Low 2.33: 2.33: 2.33: 2.33: Subscore 1.000 1.414 1.414 1.916 2.159 2.644 2.644 2.644