West Atlantic bluefin tuna Executive Summary

Biology Continued progress in knowledge of bluefin biology, but the complex behaviour of this species means that much research still needed Recent research in reproductive biology, demographic modeling and age determination suggests western bluefin may be less resilient to fishing than previously thought WG remains concerned about issues of mixing, and in particular, the inability to quantify the kind and extent of mixing for use in assessments Need to integrate recent and anticipated advances in otolith microconstituent analyses, archival tagging and genetics into assessment and management evaluation processes.

Fishery indicators: catch QUOTAS

Fishery indicators: catch 2002 landings (3,319 t) highest since 1981 Canadian and Japanese landings stable at t U.S. did not catch its quota in with landings of 899, 717, and 468 t

Fishery indicators: abundance indices No consistent changes in CPUE

Consistent with 2002 SA Less optimistic estimates of 1994 and 1997 year classes More optimistic view of recent F’s State of the stock (review)

State of stock: low U.S. catches Plausible explanations (1) that availability of fish to the United States fishery was low (2) the overall size of population in the west declined substantially Evidence (SCRS/2007/171) (1) Canada and Japan did not have abnormally low catches CPUE series from Gulf of St. Lawrence at high levels since 2004 CPUE series from GOM do not show consistent decline (2) some abundance indices suggest decline declining size composition in some areas small changes in F suggested by tag data despite declining catches Conclusion (1) No strong evidence to favor either explanation over the other (2) However, the failure of a fishery to take half of its TAC for several years, and other new evidence reviewed by the committee, heightened concern that the estimate of stock status from the 2006 assessment may be optimistic

Short-term (5-year) projections to cover time until next assessment  assume future recruitment will fluctuate around recent levels Outlook

F MSY ~ 2,100 MT

Current (2006) Catch (including discards) 1,929 t Short-term Sustainable Yield ~2,300 t Maximum Sustainable Yield (MSY|R)3,200 (3,000-3,400) Relative Spawning Stock Biomass B2004/B B2004/BMSY|R0.41 ( ) Relative Fishing Mortality 3 F2004/FMSY|R1.7 F2004/F F2004/Fmax1.7 Management Measures: 2,100 t TAC from 2007 inc. dead disc [Rec ] 2,700 t TAC from 2003 inc. dead discards [Rec ] 30 kg (115 cm FL) min. size with 8% tol. [Rec ] No directed fisheries in Gulf of Mexico [Rec ] F2004 is taken to be the geometric mean of the estimates for BFTW summary table

Effect of current regulations Recommendation expected to result in rebuilding stock towards convention objective with fishing mortality rates at about the estimated MSY level New evidence suggests that current regulations may be insufficient to achieve the objectives (cannot evaluate until next assessment) Ability to achieve the convention objectives would be further hampered by future use of accumulated unused quota (large amount involved for WBFT

Management recommendations Commission responded positively, making Rec , which establishes a quota of 2,100 MT However, the Committee is even more concerned about status of west stock than it was a year ago. Further advice provided after the next assessment (2008). Evidence accumulating that both productivity of west stock and west bluefin fisheries linked to the east stock. One plausible explanation for failure of west fishery to take TAC in recent years is that it is partly dependent on east fish, and east fish now less available to the west Therefore, management actions taken in the eastern Atlantic and Mediterranean are likely to impact recovery in the west Atlantic (SCRS 2006 Agenda Item 15.6.)