Hawaii FEP - Western Pacific Fishery Council

In addition to the thresholds MFMT and MSST, a warning reference point, B FLAG , is alsospecified at a point above the MSST to provide a trigger for consideration of management actionprior to B reaching the threshold. MFMT, MSST, and B FLAG are specified as indicated in Table20.Table 20: Overfishing Threshold Specifications:Bottomfish and Seamount GroundfishStocksMFMT MSST B FLAGFMSYBF(B) =c BMSYF(B) = Ffor B ≤ c Bfor B > cMSYMSY BMSYc BMSYB MSYwhere c = max (1-M, 0.5)Standardized values of fishing effort (E) and catch-per-unit-effort (CPUE) are used as proxies forF and B, respectively, so E MSY , CPUE MSY , and CPUE FLAG are used as proxies for F MSY , B MSY , andB FLAG , respectively. In cases where reliable estimates of CPUE MSY and E MSY are not available, theywill be estimated from catch and effort times series, standardized for all identifiable biases.CPUE MSY would be calculated as half of a multi-year average reference CPUE, called CPUE REF .The multi-year reference window would be objectively positioned in time to maximize the valueof CPUE REF . E MSY will be calculated using the same approach or, following Restrepo et al. (1998),by setting E MSY equal to E AVE , where E AVE represents the long-term average effort prior to declinesin CPUE. When multiple estimates are available, the more precautionary one is used.In Hawaii, archipelago-wide estimates of the reference points are calculated as the weightedaverage of estimates for each of the three management zones (MHI, Mau, and Hoomalu).Weighting factors are calculated using the zone-specific fraction of the total length of the 100-fmcontour in the archipelago. Ralston and Polovina (1982) have shown that the 100-fm contour is avalid measure of available bottomfish habitat. These weightings are used when calculatingarchipelago-wide F and CPUE for the deep slope complex as a whole, rather than for anyspecific BMUS.Since the MSY control rule specified in this chapter applies to multi-species stock complexes, itis important to ensure that no particular species within the complex has a mortality rate that leadsto required protection under the ESA. In order to accomplish this, a secondary set of referencepoints is specified to evaluate stock status with respect to recruitment overfishing. A secondary“recruitment overfishing” control rule is specified to control fishing mortality with respect to thatstatus. The rule is applied only to those component stocks (species) for which adequate data areavailable. The ratio of a current spawning stock biomass proxy (SSBP t ) to a given reference level(SSBP REF ) is used to determine if individual stocks are experiencing recruitment overfishing.SSBP is CPUE scaled by percent mature fish in the catch. When the ratio SSBP t /SSBP REF , or the“SSBP ratio” (SSBPR) for any species drops below a certain limit (SSBPR MIN ), that species isconsidered to be recruitment overfished and management measures will be implemented toreduce fishing mortality on that species. The rule applies only when the SSBP ratio drops belowthe SSBPR MIN , but it will continue to apply until the ratio achieves the “SSBP ratio recovery144