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

More documents

Recommendations

Info

EXECUTIVE SUMMARY YFTavailable catch distribution is given in YFT-Figure 1. The provisional catches for 2007 (96,580 t) are nearlycomplete, and suggest a slight decrease from 2006.The nominal effort in the purse seine fishery has been declining. As an indicator, the number of purse seinersfrom the European and associated fleet operating in the Atlantic declined from 44 vessels in 2001 to 24 vesselsin 2006, with an average age of about 25 years. The number of fishing days also declined by nearly 50%. At thesame time, the efficiencies of these fleets have been increasing. On the other hand, the European and associatedbaitboat fleet, based in Dakar, increased from 15 to 17 vessels during the same period.Several scientific documents were presented which were descriptive of the catches by country fleets.Examination of nominal catch rate trends from purse seine data suggest that catch-per-unit effort was stable orincreasing in the East Atlantic (the catch rate trends of individual country fleets differ somewhat), and wasclearly declining in the West Atlantic (YFT-Figure 3). If effort efficiency is estimated to have continued toincrease as has been assumed in the past, adjustments for such efficiency change would be expected to result in asteeper declining trend. However, the decrease in western Atlantic purse seine catch rates could be linked tospecific environmental conditions (e.g. high surface temperatures, reduced availability of prey, etc.), especiallyconsidering that decreases are also seen in skipjack catch rates, and it is therefore difficult to conclude that theserates reflect abundance trends. Baitboat catch rate trends (YFT-Figure 4) exhibit large fluctuations, with asomewhat declining overall trend. Such large fluctuations reflect changes in local availability, which (althoughof great import to the respective fisheries) do not necessarily reflect stock abundance trends (i.e. localizedenvironmental changes as well as changes in migratory patterns may produce such results). Standardized catchrates for the longline fisheries (YFT-Figure 5) generally show a declining trend until the mid-1990s, and havefluctuated without clear trend since.The average weight trends by fleet (1970-2006) are shown in YFT-Figure 6. The recent average weight inEuropean purse seine catches, which represent the majority of the landings, has declined to less than half of theaverage weight of 1990. This decline is at least in part due to changes in selectivity associated with fishing onfloating objects, although there have been recent indications that the mean weight of large fish caught in freeschools has been declining. A declining trend is also reflected in the average weight of eastern tropical baitboatcatches. Longline mean weights have also followed a generally declining trend, although estimates have beenhighly variable in recent years.Apparent changes in selectivity can also be seen in the overall trends in catch at age shown in YFT-Figure 7.The variability in overall catch at age is primarily due to variability in catches of ages 0 and 1 (note that thecatches in numbers of ages 0 and especially 1 were particularly high during the period 1999-2001). These agesare generally taken by the surface fisheries around FADs.YFT-3. State of the stockSince the relatively high catch levels of 2001 (164,650 t), catches have declined each year to a level of 108,160 t,a reduction of 34%. Catches in 2005 and 2006 represented the lowest level of catches since 1974. The catch in2007 (96,580 t) is preliminary, but may be even lower. A potential explanation for this decline is the reduction ineastern Atlantic purse seine effort, but that alone does not explain the reduction of baitboat and purse seinecatches in the western Atlantic, nor the more recent declines of longline catches in both the western and easternAtlantic. A full stock assessment was conducted for yellowfin tuna in 2008, applying both an age-structuredmodel and a non-equilibrium production model to the available catch data through 2006.An age-structured virtual population analysis (VPA) was conducted using fifteen indices of abundance. TheVPA, using results from the base case runs, estimates that the levels of fishing mortality and spawning biomassin recent years have been very close to MSY levels. The estimate of MSY derived from these analyses was130,600 t. This estimate may be below what was achieved in past decades because overall selectivity has shiftedto smaller fish (YFT-Figure 7); the impact of this change in selectivity on estimates of MSY is clearly seen inthe results from VPA (YFT-Figure 8). The estimate of relative fishing mortality (F 2006 /F MSY) was 0.84, and forrelative biomass (B 2006 /B MSY ) was 1.09.The stock was also assessed with a production model (ASPIC). Analyses were conducted using either nineseparate indices or using a combined index created from all available abundance indices by fleet and gear, andweighting each index by the area covered by that fishery. The estimate of MSY derived using the basic case runsof ASPIC was 146,600 t. Although the estimate of MSY was somewhat higher than that from the age structured17
ICCAT <strong>REPORT</strong> 2008-2009 (I)model, the stock status results are slightly more pessimistic. The estimate of relative fishing mortality(F 2006 /F MSY) was 0.89, and for relative biomass (B 2006 /B MSY ) was 0.83.Trajectories of B/B MSY and F/F MSY from both age structured (VPA) and the production model (ASPIC) analysesare shown in YFT-Figure 9. The trend estimated from VPA indicates that overfishing (F>F MSY ) has occurred inrecent years, but that the current status is neither overfished (B
Page 1: INTERNATIONAL COMMISSION FOR THECON
Page 6 and 7: SCRS PLENARY SESSIONS 1 to 8The Coo
Page 9: ICCAT REPORT 2008-2009 (I)There is
Page 12 and 13: SCRS PLENARY SESSIONS 1 to 8Korean
Page 14 and 15: SCRS PLENARY SESSIONS 1 to 8Senegal
Page 16 and 17: SCRS PLENARY SESSIONS 1 to 8Informa
Page 18 and 19: SCRS PLENARY SESSIONS 1 to 8The Com
Page 22 and 23: EXECUTIVE SUMMARY YFTYFT-6. Managem
Page 24 and 25: 1983 1984 1985 1986 1987 1988 1989
Page 26 and 27: EXECUTIVE SUMMARY YFT250000YFT. Tas
Page 28 and 29: EXECUTIVE SUMMARY YFT6050BBLLothPS4
Page 30 and 31: EXECUTIVE SUMMARY YFTYFT-Figure 9.
Page 32 and 33: EXECUTIVE SUMMARY YFTYFT-Figure 13.
Page 34 and 35: EXECUTIVE SUMMARY BETthe West Atlan
Page 36 and 37: EXECUTIVE SUMMARY BETbe encouraged,
Page 38 and 39: 1983 1984 1985 1986 1987 1988 1989
Page 40 and 41: ICCAT REPORT 2008-2009 (I)BET-Figur
Page 42 and 43: ICCAT REPORT 2008-2009 (I)BET-Figur
Page 44 and 45: EXECUTIVE SUMMARY SKJcatches, suppo
Page 46 and 47: EXECUTIVE SUMMARY SKJlead to involu
Page 48 and 49: 1983 1984 1985 1986 1987 1988 1989
Page 50 and 51: EXECUTIVE SUMMARY SKJSKJ-Figure 2.
Page 58 and 59: EXECUTIVE SUMMARY ALBAdditionally m
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
Page 66 and 67: ICCAT REPORT 2008-2009 (I)c)9000800
Page 68 and 69: ICCAT REPORT 2008-2009 (I)4.03.53.0
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
Page 76 and 77:
EXECUTIVE SUMMARY BFTconsistent bet
Page 78 and 79:
EXECUTIVE SUMMARY BFTCurrent (2006)
Page 80 and 81:
EXECUTIVE SUMMARY BFTinformation th
Page 82 and 83:
BFT-Table 1. Reported catches(t) in
Page 84 and 85:
EXECUTIVE SUMMARY BFTa. BFT(1950‐
Page 86 and 87:
EXECUTIVE SUMMARY BFT6000050000Unre
Page 88 and 89:
EXECUTIVE SUMMARY BFT0.4F(1-5)0.5F(
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
Page 96 and 97:
EXECUTIVE SUMMARY BUM/WHMIt should
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
Page 104 and 105:
EXECUTIVE SUMMARY BUM/WHMWHM BUM Un
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
Page 112 and 113:
EXECUTIVE SUMMARY SWO-ATLalso been
Page 114 and 115:
EXECUTIVE SUMMARY SWO-ATLOther impl
Page 116 and 117:
1983 1984 1985 1986 1987 1988 1989
Page 118 and 119:
EXECUTIVE SUMMARY SWO-ATLSWO-ATL Fi
Page 120 and 121:
EXECUTIVE SUMMARY SWO-ATL12001000cp
Page 122 and 123:
EXECUTIVE SUMMARY SWO-MED8.9 SWO-ME
Page 124 and 125:
EXECUTIVE SUMMARY SWO-MEDeither in
Page 126 and 127:
EXECUTIVE SUMMARY SWO-MED25000SWO-M
Page 128 and 129:
EXECUTIVE SUMMARY SWO-MEDSWO-MED-Fi
Page 130 and 131:
EXECUTIVE SUMMARY SBF8.10 SBF - SOU
Page 132 and 133:
EXECUTIVE SUMMARY SMTSCRS/2008/042
Page 134 and 135:
SMT-Table 1. Best scientific estima
Page 136 and 137:
1983 1984 1985 1986 1987 1988 1989
Page 138 and 139:
1983 1984 1985 1986 1987 1988 1989
Page 140 and 141:
EXECUTIVE SUMMARY SMTSMT-Figure 1.
Page 142 and 143:
EXECUTIVE SUMMARY SMT139
Page 144 and 145:
EXECUTIVE SUMMARY SMTSMT-Figure 2.
Page 146 and 147:
EXECUTIVE SUMMARY SHKparameters), a
Page 148 and 149:
SHK-Table 1. Estimated catches (t)
Page 150 and 151:
1983 1984 1985 1986 1987 1988 1989
Page 152 and 153:
EXECUTIVE SUMMARY SHKSHK-Figure 1.
Page 154 and 155:
EXECUTIVE SUMMARY SHKSHK-Figure 4.
Page 156 and 157:
SCRS PLENARY SESSIONS 9 to 17includ
Page 158 and 159:
SCRS PLENARY SESSIONS 9 to 179.9 Sh
Page 160 and 161:
SCRS PLENARY SESSIONS 9 to 1713.1 A
Page 162 and 163:
SCRS PLENARY SESSIONSBrazil informe
Page 164 and 165:
SCRS PLENARY SESSIONS−−−Effor
Page 166 and 167:
SCRS PLENARY SESSIONSData deficienc
Page 168 and 169:
SCRS PLENARY SESSIONS15.5 Other con
Page 170 and 171:
SCRS PLENARY SESSIONS16.5 Profile f
Page 172 and 173:
PARTICIPANTSAppendix 2LIST OF PARTI
Page 174 and 175:
PARTICIPANTSDe Bruyn, Paul*AZTI - T
Page 176 and 177:
PARTICIPANTSKOREAHwang, Seon-JaeNat
Page 178 and 179:
PARTICIPANTSURUGUAYDomingo, Andrés
Page 180 and 181:
PARTICIPANTSICCAT SECRETARIATC/ Cor
Page 182 and 183:
LIST OF DOCUMENTSSCRS/2008/033Analy
Page 184 and 185:
LIST OF DOCUMENTSSCRS/2008/071SCRS/
Page 186 and 187:
LIST OF DOCUMENTSSCRS/2008/109Estan
Page 188 and 189:
LIST OF DOCUMENTSSCRS/2008/143 Dist
Page 190 and 191:
LIST OF DOCUMENTSSCRS/2008/179Preli
Page 192 and 193:
OPENING ADDRESSOPENING ADDRESS OF D
Page 194 and 195:
WORK PLANS FOR 2009Before the asses
Page 196 and 197:
WORK PLANS FOR 2009− The estimati
Page 198 and 199:
WORK PLANS FOR 2009Sharks Work Plan
Page 200 and 201:
BYP ACTIVITIESFor the 2007-2008 per
Page 202 and 203:
BYP ACTIVITIES4.2 The MIGRATUN proj
Page 204 and 205:
BILLFISH RESEARCH PROGRAMthe contin
Page 206 and 207:
BILLFISH RESEARCH PROGRAMTable 1. S
Page 208 and 209:
SUB-COM STATISTICSREPORT OF THE 200
Page 210 and 211:
SUB-COM STATISTICS3.2.2 Revision of
Page 212 and 213:
SUB-COM STATISTICS5.2 Responses to
Page 214 and 215:
SUB-COM STATISTICSwill soon be prov
Page 216 and 217:
SubCom Stats Report Table 1. Report
Page 218 and 219:
SUB-COM STATISTICSAddendum 1 to App
Page 220 and 221:
SUB-COM STATISTICSHarmonization of
Page 222 and 223:
SUB-COM STATISTICSFor by-catch in g
Page 224 and 225:
SUB-COM STATISTICS9. Other recommen
Page 226 and 227:
SUB-COM ECOSYSTEMSwaters, it shows
Page 228 and 229:
SUB-COM ECOSYSTEMSprioritize future
Page 230 and 231:
Uruguay Uruguay PelagicLonglineCana
Page 232 and 233:
SUB-COM ECOSYSTEMSReverse side229
Page 234 and 235:
EXAMPLE FORMS: TASK II INFOAPPENDIX
Page 236 and 237:
EXAMPLE FORMS: TASK II INFOPROGRAMA
Page 238 and 239:
EXAMPLE FORMS: TASK II INFOPrograma
Page 240 and 241:
BY-CATCH COORD. PROFILEAppendix 11I
show all

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

Create successful ePaper yourself

Delete template?

Save as template?