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.F ishing is a risky business. Not only do fishermen face the highest rate of work-related fatalities of any US industry, with a fatality rate more than 30 times higher than average (1), they face high financial risk as a result of high year-to-year variation in their income (2). In this article we focus on the latter form of risk. High annual variation in income is a problem that is common to a variety of occupations dependent on natural resources, and there has been extensive study of income risk-coping mechanisms, particularly for farmers in developing countries (3-10). Riskreduction strategies used in agriculture might also be effective in fisheries. Crop diversification is a common means of reducing risk in agriculture, taking advantage of asynchronous variation in yield-response and prices to minimize idiosyncratic risk (11-13). Another common strategy in agriculture, particularly in semiarid regions with high fine-scale variation in rainfall, is to farm a number of geographically separated plots to ensure some will be in areas with sufficient rainfall (6). McCloskey (14) argues that risk reduction was the motivation of English farmers for "scattering each man's holdings in dozens of small strips" which, although inefficient, was widely practiced. Farmers can also plant a combination of crops adapted to wet or dry conditions to mitigate the risk assoc...