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

SCRS PLENARY SESSIONS15.5 Other considerations about the ability to monitor the eastern bluefin tuna recovery planRecommendation [06-05] calls for the SCRS to "monitor and review the progress of the Plan and submit anassessment to the Commission for the first time in 2008, and each two years thereafter". The Committee's overallassessment of the progress of the Plan in relation to stock status is given in the Executive Summary (Section8.5). This section provides additional considerations about the task given to SCRS.Management measures (Part II of the Plan):−−−−TAC and Quotas: The Committee estimates that the TAC was exceeded substantially in 2007, the first yearwhen the Plan came into effect (see Section 8).Closed fishing seasons: This matter may be more pertinent to the Compliance Committee.Use of aircraft: This matter may be more pertinent to the Compliance Committee.Minimum size: Very little Task II (size) information for 2007 was reported in time for the assessmentmeeting, when a detailed analysis would have been possible (see ICCAT Circular #1227/08).− By-catch: Very little Task II (size) information for 2007 was reported in time for the assessmentmeeting, when a detailed analysis would have been possible (see ICCAT Circular #1227/08).−−Recreational fisheries: No catch data for 2007 that are explicitly associated with recreational fisheries havebeen reported to SCRS.Sport fisheries: No catch data for 2007 that are explicitly associated with sport fisheries have been reportedto SCRS.Observer Programs (paragraphs 50 and 51 of the Plan):The Committee's understanding of the objective of the Plan's observer program is that it is for compliancepurposes, until such time that the Commission decides that the programs should also be used to carry outscientific work. At that time, SCRS will have to develop specific directions of how to collect and report therequired data. However, it is possible for Contracting Parties to use the observer programs to collect Task IIinformation without waiting for the Commission to mandate such type of data collection. Appendix 10 showstwo example forms used by EC-France and EC-Spain to collect Task II information.15.6 Strategies to increase the yield per recruit and MSY of bigeye tuna by reducing mortality on smallbigeye tunaIn the report of Panel 1 of the Commission, it was suggested that the SCRS analyze and present a range ofoptions to the Commission to increase the yield per recruit and MSY of bigeye tuna by reducing mortality onsmall bigeye tuna through the use of such measures as closed areas (i.e. total closure of all surface fisheries) andmoratoriums on the use of Fish Aggregating Devices (FADs). It was also suggested that the SCRS analyze theimpacts of such measures on the catches of yellowfin tuna and skipjack tuna. In accordance with thesesuggestions, a versatile tool was developed to enable the analysis of the potential impacts of adjustments toeffective effort levels and/or the selectivity patterns of individual fisheries.The Committee used this tool to conduct a limited evaluation on the relative impact of effective effortrestrictions on individual fisheries in terms of yield per recruit and spawning biomass per recruit. This evaluationis presented separately as part of an annex to the Detailed Report of the 2008 SCRS Stock Assessment ofYellowfin of Skipjack and Yellowfin Tuna. In these analyses, the Committee examined effect of reducing orincreasing the effective effort of two fleets, the equatorial surface fleet (EU purse seine and Ghana) and anaggregate fleet (all others), on the yield-per-recruit (YPR) and spawning stock biomass-per-recruit (SPR) ofyellowfin and bigeye tunas. An evaluation of the impact on skipjack tuna was not conducted as estimates offishing mortality-at-age, which are required for these analyses, are not currently available for those stocks.The results of these analyses indicate that modest gains in YPR for yellowfin and bigeye can be obtained bysimultaneously decreasing considerably the surface fleet fishing mortality and noticeably increasing the fishingmortality exerted by the other fleets. The results also show that increases in effective effort levels, particularlythat of the surface fleets, would likely result in substantial reductions in SPR. One implication of these results isthat it would be more difficult to maintain spawning stock biomass at high levels under scenarios such as areallocation of surface fleet effort from other oceans toward the tropical Atlantic.165