Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98115, USA.
Proc Natl Acad Sci U S A. 2013 Feb 5;110(6):2076-81. doi: 10.1073/pnas.1212278110. Epub 2013 Jan 22.
Catches and prices from many fisheries exhibit high interannual variability, leading to variability in the income derived by fishery participants. The economic risk posed by this may be mitigated in some cases if individuals participate in several different fisheries, particularly if revenues from those fisheries are uncorrelated or vary asynchronously. We construct indices of gross income diversification from fisheries at the level of individual vessels and find that the income of the current fleet of vessels on the US West Coast and in Alaska is less diverse than at any point in the past 30 y. We also find a dome-shaped relationship between the variability of individuals' income and income diversification, which implies that a small amount of diversification does not reduce income risk but that higher levels of diversification can substantially reduce the variability of income from fishing. Moving from a single fishery strategy to a 50-25-25 split in revenues reduces the expected coefficient of variation of gross revenues between 24% and 65% for the vessels included in this study. The increasing access restrictions in many marine fisheries through license reductions and moratoriums have the potential to limit fishermen's ability to diversify their income risk across multiple fisheries. Catch share programs often result in consolidation initially and may reduce diversification. However, catch share programs also make it feasible for fishermen to build a portfolio of harvest privileges and potentially reduce their income risk. Therefore, catch share programs create both threats and opportunities for fishermen wishing to maintain diversified fishing strategies.
许多渔业的捕捞量和价格表现出高度的年际可变性,导致渔业参与者的收入也随之波动。如果个体参与多个不同的渔业,这种经济风险在某些情况下可能会得到缓解,特别是如果这些渔业的收入不相关或变化不同步。我们构建了个体船只渔业总收入多样化的指标,发现美国西海岸和阿拉斯加目前船队的收入比过去 30 年的任何时候都更加单一。我们还发现个体收入变化和收入多样化之间呈圆顶形关系,这意味着少量多样化并不能降低收入风险,但更高水平的多样化可以大大降低捕鱼收入的可变性。从单一渔业策略转变为收入 50-25-25 的分配,可以将本研究中包含的船只总收入的预期变异系数降低 24%至 65%。许多海洋渔业的准入限制通过减少许可证和暂停捕捞的方式不断增加,这有可能限制渔民在多个渔业中分散收入风险的能力。捕捞份额计划通常最初会导致集中化,并可能减少多样化。然而,捕捞份额计划也使渔民有可能建立一揽子捕捞特权,并有可能降低他们的收入风险。因此,捕捞份额计划为希望维持多样化捕捞策略的渔民既带来了威胁,也带来了机遇。