ASSESSMENT AND FISHERIES MANAGEMENT OF EASTERN BERING SEA WALLEYE POLLOCK: IS SUSTAINABILITY LUCK?

摘要

Alaska pollock is the largest component of white-fish production worldwide representing about 45% of all white fish. The portion of pollock caught within U.S. waters has been stable, averaging around 1.2 million t over the last two decades. The condition of the eastern Bering Sea (EBS) pollock stock in 2001 appears to be quite healthy with biomass levels estimated to be around 10 million t. These estimates have a relatively large degree of uncertainty, even though fishery monitoring and survey efforts for this stock are extensive. Part of this uncertainty can be attributed to variable stock dynamics, including spatial variability due to environmental conditions and demographic variability such as pre-recruit survival, natural mortality, and growth. At some point, improving observations on current stock conditions give diminishing returns on improving forecast abundance. Long-term projections illustrate that, given the level of observed recruitment variability, stock biomass levels can vary quite widely, even under little or no fishing. So, how has the pollock fishery become sustainable? In part, early decisions to closely regulate fishing (using truly effective quotas and hence effort rationalization) have led to a successful and so far, sustainable fishery. In addition, an overall cap on total groundfish removals (2 million mt) from the EBS ecosystem has limited individual stock quotas and hence led to a stabilized fishery well within the bounds of sound conservation principals. The combination of effective management regimes together with a rationally developed fishery appear to be ideal for sustaining the Alaskan pollock resource and fisheries.