REPORT OF THE STANDING COMMITTEE ON RESEARCH ... - Iccat

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EXECUTIVE SUMMARY BFTCurrent (2006) Yield 1Current (2007) Yield 1Short-term Sustainable Yield 2F MAXF 0.1Long-term potential yield 3SSB 2007 /SSB FMAXHigh recruitment (1990s)Low recruitment (1970s)4F 2007 /F MAXReported catchesAjusted catchesTAC (2007-2010)EAST ATLANTIC AND MEDITERRANEAN BLUEFIN TUNA SUMMARYReported: 30,647 tReported: 32,398 t15,000 t or less8,500 t or lessabout 50,000 t0.140.353.043.4229,500 - 28,500 - 27,500 - 25,500 tSCRS Estimate for 2006: 50,000 tSCRS Estimate for 2007: 61,000 t1 Correspond to the reported catches on the September 25, 2008.2 Approximated as a 4-years average yield expectation from the 2010-2013 constant F MAX or F 0.1 projections.3 Approximated as the average of long-term yield at F MAX or F 0.1 that were calculated over a broad range of scenarios including contrastingrecruitment levels and different selectivity patterns (estimates from these scenarios ranged between 29,000 t and 91,000 t).4 The recruitment levels do not impact the F ratio.75
ICCAT <strong>REPORT</strong> 2008-2009 (I)BLUEFIN TUNA - WESTBFTW-2. Fishery indicatorsThe total catch for the West Atlantic peaked at nearly 20,000 t in 1964, mostly due to the Japanese longlinefishery for large fish off Brazil and the United States purse seine fishery for juvenile fish (BFT-Table 1, BFTW-Figure 1). Catches dropped sharply thereafter with the collapse of the longline fishery off Brazil and decline inpurse seine catches, but increased again to average over 5,000 t in the 1970s due to the expansion of the Japaneselongline fleet into the northwest Atlantic and Gulf of Mexico and an increase in purse seine effort targetinglarger fish for the sashimi market. The total catch for the West Atlantic including discards has generally beenrelatively stable since 1982 due to the imposition of quotas. However, since a total catch level of 3,319 t in 2002(the highest since 1981, with all three major fishing nations indicating higher catches), total catch in the WestAtlantic has declined steadily reaching 1,624 t in 2007 (BFTW-Figure 1). This decline is primarily due toconsiderable reductions in catch levels for United States fisheries. Since 2002, the Canadian annual catches havebeen relatively stable at about 500-600 t (733 t in 2006); the 2006 catch was the highest recorded since 1977.Japanese catches have generally fluctuated between 300-500 t, with the exception of 2003 (57 t), which was lowfor regulatory reasons. The overall number of Japanese vessels engaged in bluefin fishing has declined frommore than 100 boats in recent years to about 50 boats in 2007, of which about 20 boats operated in the WestAtlantic. After reaching 2,014 t in 2002 (the highest level since 1979), the catches (landings and discards) ofU.S. vessels fishing in the northwest Atlantic (including the Gulf of Mexico) declined precipitously during 2003-2007. The United States did not catch its quota in 2004-2007 with catches of 1,066, 848, 615, and 849 t,respectively. It was noted that some nations have adopted a fishing year that is different from the calendar yearto manage their quota.BFTW-3. State of the stockAn updated assessment was conducted this year, including information up to 2007. This assessment is consistentwith previous analyses in that spawning stock biomass (SSB) declined steadily between the early 1970s and1992. Since then, SSB has fluctuated between 18% and 27% of the 1975 level (BFTW-Figure 2). The stock hasexperienced different levels of fishing mortality (F) over time, depending on the size of fish targeted by variousfleets (BFTW-Figure 2). Fishing mortality on spawners (ages 8 and older) declined markedly between 2002 and2007.Estimates of recruitment were very high in the early 1970’s (BFTW-Figure 2), and additional analysesinvolving longer catch and index series suggest that recruitment was also high during the 1960s. Since 1977,recruitment has varied from year to year without trend. The Committee noted that a key factor in estimatingMSY-related benchmarks is the highest level of recruitment that can be achieved in the long term. Assuming thataverage recruitment cannot reach the high levels from the early 1970s, recent F (2004-2006) is about 30% higherthan the MSY level and SSB is about half of the MSY level (BFTW-Figure 3). Estimates of stock status aremore pessimistic if a high recruitment scenario is considered (F/F MSY =2.1, B/B MSY =0.14).One important factor in the recent decline of fishing mortality on large bluefin is that the TAC has not beentaken during this time period, due primarily to a shortfall by the United States fisheries that target large bluefin.Two plausible explanations for the shortfall were put forward previously by the Committee: (1) that availabilityof fish to the United States fishery has been abnormally low, and/or (2) the overall size of the population in theWestern Atlantic declined substantially from the level of recent years. While there is no overwhelming evidenceto favor either explanation over the other, the base case assessment implicitly favors the first hypothesis(regional changes in availability) because a large recent reduction in SSB is not estimated. Nevertheless, theCommittee notes that there remains substantial uncertainty on this issue and more research needs to be done.The SCRS cautions that the conclusions of this assessment do not capture the full degree of uncertainty in theassessments and projections. An important factor contributing to uncertainty is mixing between fish of easternand western origin. Limited analyses were conducted of the two stocks with mixing. Depending on the types ofdata used to estimate mixing (conventional tagging or isotope signature samples) and modeling assumptionsmade, the estimates of stock status varied considerably. However, these analyses are preliminary and moreresearch needs to be done before mixing models can be used operationally for management advice. Anotherimportant source of uncertainty is recruitment, both in terms of recent levels (which are estimated with lowprecision in the assessment), and potential future levels (the "low" vs "high" recruitment hypotheses which affectmanagement benchmarks). Finally, the growth curve assumed in the analyses may be revised based on new76
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INTERNATIONAL COMMISSION FOR THECON
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SCRS PLENARY SESSIONS 1 to 8The Coo
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ICCAT REPORT 2008-2009 (I)There is
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SCRS PLENARY SESSIONS 1 to 8Korean
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SCRS PLENARY SESSIONS 1 to 8Senegal
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SCRS PLENARY SESSIONS 1 to 8Informa
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SCRS PLENARY SESSIONS 1 to 8The Com
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EXECUTIVE SUMMARY YFTavailable catc
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EXECUTIVE SUMMARY YFTYFT-6. Managem
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1983 1984 1985 1986 1987 1988 1989
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EXECUTIVE SUMMARY YFT250000YFT. Tas
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Page 34 and 35: EXECUTIVE SUMMARY BETthe West Atlan
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Page 60 and 61: EXECUTIVE SUMMARY ALBALB-4. Outlook
Page 62 and 63: ALB-Table 1. Estimated catches (t)
Page 64 and 65: ICCAT REPORT 2008-2009 (I)ALB-Figur
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Page 70 and 71: ICCAT REPORT 2008-2009 (I)Ratio4.54
Page 72 and 73: ICCAT REPORT 2008-2009 (I)Spawning
Page 74 and 75: EXECUTIVE SUMMARY BFT8.5 BFT - ATLA
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Page 90 and 91: EXECUTIVE SUMMARY BFTBFTW-Table 1.
Page 92 and 93: EXECUTIVE SUMMARY BFTNumber of year
Page 94 and 95: EXECUTIVE SUMMARY BUM/WHM8.6 BLUE M
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Page 98 and 99: BUM-Table 1. Estimated catches (t)
Page 100 and 101: WHM-Table 1. Estimated catches (t)
Page 102 and 103: EXECUTIVE SUMMARY BUM/WHM.BUM/WHM-F
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Page 106 and 107: EXECUTIVE SUMMARY SAIrecent trends
Page 108 and 109: EXECUTIVE SUMMARY SAISAI-Figure 1.
Page 110 and 111: EXECUTIVE SUMMARY SAIa)Relative Abu
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Page 122 and 123: EXECUTIVE SUMMARY SWO-MED8.9 SWO-ME
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EXECUTIVE SUMMARY SWO-MEDSWO-MED-Fi
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EXECUTIVE SUMMARY SBF8.10 SBF - SOU
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EXECUTIVE SUMMARY SMTSCRS/2008/042
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SMT-Table 1. Best scientific estima
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1983 1984 1985 1986 1987 1988 1989
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EXECUTIVE SUMMARY SMTSMT-Figure 1.
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EXECUTIVE SUMMARY SMT139
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EXECUTIVE SUMMARY SMTSMT-Figure 2.
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EXECUTIVE SUMMARY SHKparameters), a
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SHK-Table 1. Estimated catches (t)
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1983 1984 1985 1986 1987 1988 1989
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EXECUTIVE SUMMARY SHKSHK-Figure 1.
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EXECUTIVE SUMMARY SHKSHK-Figure 4.
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SCRS PLENARY SESSIONS 9 to 17includ
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SCRS PLENARY SESSIONS 9 to 179.9 Sh
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SCRS PLENARY SESSIONS 9 to 1713.1 A
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SCRS PLENARY SESSIONSBrazil informe
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SCRS PLENARY SESSIONS−−−Effor
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SCRS PLENARY SESSIONSData deficienc
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SCRS PLENARY SESSIONS15.5 Other con
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SCRS PLENARY SESSIONS16.5 Profile f
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PARTICIPANTSAppendix 2LIST OF PARTI
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PARTICIPANTSDe Bruyn, Paul*AZTI - T
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PARTICIPANTSKOREAHwang, Seon-JaeNat
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PARTICIPANTSURUGUAYDomingo, Andrés
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PARTICIPANTSICCAT SECRETARIATC/ Cor
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LIST OF DOCUMENTSSCRS/2008/033Analy
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LIST OF DOCUMENTSSCRS/2008/071SCRS/
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LIST OF DOCUMENTSSCRS/2008/109Estan
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LIST OF DOCUMENTSSCRS/2008/143 Dist
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LIST OF DOCUMENTSSCRS/2008/179Preli
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OPENING ADDRESSOPENING ADDRESS OF D
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WORK PLANS FOR 2009Before the asses
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WORK PLANS FOR 2009− The estimati
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WORK PLANS FOR 2009Sharks Work Plan
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BYP ACTIVITIESFor the 2007-2008 per
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BYP ACTIVITIES4.2 The MIGRATUN proj
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BILLFISH RESEARCH PROGRAMthe contin
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BILLFISH RESEARCH PROGRAMTable 1. S
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SUB-COM STATISTICSREPORT OF THE 200
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SUB-COM STATISTICS3.2.2 Revision of
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SUB-COM STATISTICS5.2 Responses to
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SUB-COM STATISTICSwill soon be prov
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SubCom Stats Report Table 1. Report
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SUB-COM STATISTICSAddendum 1 to App
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SUB-COM STATISTICSHarmonization of
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SUB-COM STATISTICSFor by-catch in g
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SUB-COM STATISTICS9. Other recommen
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SUB-COM ECOSYSTEMSwaters, it shows
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SUB-COM ECOSYSTEMSprioritize future
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Uruguay Uruguay PelagicLonglineCana
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SUB-COM ECOSYSTEMSReverse side229
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EXAMPLE FORMS: TASK II INFOAPPENDIX
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EXAMPLE FORMS: TASK II INFOPROGRAMA
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EXAMPLE FORMS: TASK II INFOPrograma
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BY-CATCH COORD. PROFILEAppendix 11I
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