Purpose and Need

The MSA requires conservation and management measures to prevent overfishing, but does not define overfishing. NOAA guidelines require that each FMP specify an objective and measurable definition of overfishing for included stocks. This amendment established quantitative definitions of overfishing, replacing the qualitative definitions originally included in the FMP. 

Analysis

A 28 page EA, dated November 20, 1990, was prepared for this amendment. Four alternatives, including the status quo, were evaluated. The alternative chosen defined overfishing as a constant rate of fishing mortality in excess of Fmsy. The other alternatives considered included a variable fishing rate, or a constant fishing mortality rate with a MSST set at 10 percent of the long term average biomass. The variable rate alternative was not chosen due to data limitations, the extensive analysis required, and the development of new harvest strategies by the State of Alaska. The threshold alternative was not chosen because it could not be determined if the 10 percent biomass could be estimated for most stocks, and whether this level of reserve would be a conservative measure. 

Regulation Summary

This amendment defined overfishing as a fishing mortality rate in excess of Fmsy where the maximum allowable fishing mortality rate is estimated to equal the natural mortality rate (M) of mature male crab. Depending on the data availability for a stock, fishing mortality and the maximum allowable fishing mortality rate was estimated with different methods. For stocks with only historical catch, sporadic inseason catch, effort, and mortality data, the maximum allowable fishing mortality rate was 0.3. Mortality rate estimates are generated from CPUE data. For stocks with historical catch, continuous inseason catch and effort, as well as mortality data, the maximum allowable fishing mortality rate was 0.3. Fishing mortality and cumulative catch were used to estimate the population of legal male crab and fishing mortality rates. Finally, for stocks with historical catch, continuous inseason catch and effort, as well as population dynamics data available, the maximum allowable fishing mortality rate was 0.1. Harvest levels were estimated annually and fishing mortality rates were established prior to the fishery. 

Results

This provided clear and objective overfishing definitions that the fisheries could be predictably managed in accordance with. These stock status thresholds have been foundational for the effective management of BSAI crab and other North Pacific Stocks. Overfishing definitions and related biological and management thresholds have been continually updated as new information become available. For the BSAI Crab FMP, these updates were done under Amendments 7, 24, and 38.