Has the MSA led to stock rebuilding - a synthesis of all U.S. Overfished Stocks?

PARMA, A.M.

Seattle

Simposio; The Bevan Series on Sustainable Fisheries-Issues at the fore in the land of Magnuson and Stevens; 2014

School of Fisheries and Aquatic Sciences

A National Research Council Committee was established in 2012 to evaluate the effectiveness of federally implemented rebuilding plans mandated by the MSA. The study focused on 85 stocks that were declared overfished over the period 1997-2011. Rebuilding plans were implemented for 79 of these stocks while 5 other stocks were declared rebuilt before a rebuilding plan was adopted. Estimated trends in biomass and fishing mortality relative to MSY-reference points (or proxies), available for a subset of 55 stocks, showed marked reductions in fishing mortality for most stocks placed under rebuilding plans, generally followed by an increase in stock biomass. Although some stocks were declared rebuilt by 2012 (the period covered by the review), others were still below rebuilding targets (34 of 55), and some of those continued to be subject to overfishing (14 of 55) despite fishing mortality targets being set at or below 75% FMSY to allow for at least a 50% probability of rebuilding within the maximum time limit. The failure of these rebuilding plans to achieve the intended reductions in fishing mortality reflects implementation problems due to ineffective input controls and lack of accountability measures prior to 2007, difficulties reducing fishing mortality of species caught as bycatch in other fisheries, or overestimation of stock size. Stocks that rebuilt or whose biomass increased appreciably were, in almost all cases reviewed, experiencing fishing mortalities below FMSY, and often lower than 75% of FMSY. The variable or mixed performance of rebuilding plans was attributed in part to uncertainty in the determination of stock status relative to reference points, and the fact that estimates of stock size and productivity often change markedly between successive assessments. The current policy dependence on biomass thresholds and targets often causes abrupt changes in management, exacerbating the impact of the inherent variability and uncertainty of stock assessments.