Social-Ecological Factors Influencing Responses of Fisheries to El Nino-Southern Oscillation Events (ENSO)

Environmental shocks may strongly affect fisheries. However, it is not well understood how environmental shocks affect multi-species fisheries at a regional scale or how biological, institutional, and economic factors mediate the effects of environmental shocks on fisheries. ENSO, an important environmental shock, may directly affect fish populations through changes in natural mortality and food availability. However, fish catch may not reflect ENSO events because fishermen’s decisions are affected by ENSO-induced changes in fish abundance as well as institutional constraints and prices. We tested the relative effects of these factors using regional datasets from the Gulf of California, Mexico. Fish catch responded more quickly to ENSO events for species where ENSO affected adult stages rather than recruit stages. However, institutional constraints, such as commercial sizes, buffered the effect of ENSO on fish catches by limiting fishermen’s ability to harvest ENSO-induced “surpluses.” In contrast, high export prices for fish species may have exacerbated the negative effects of ENSO by limiting the effect of increased costs associated with changes in fish abundance and maintaining fish catch while fish abundance was low. These results suggest that economic factors may make overfished populations more vulnerable to reaching critically low levels following negative environmental shocks.