Effects of spatial closures on California trawl fishing effort

Spatial closures are one of several strategies used to manage the multi-species groundfish trawl fishery in California since 2002 to rebuild overfished species. We analyze the effects of the closures on total effort and the spatial distribution of effort using logbook data on the location and duration of trawls. The proportion of effort in various fishing locations before and after the closures are examined to determine if locations outside the closures experienced increased fishing effort. The species composition of the catch from these areas is examined. To assess how implementation of the closures influenced total effort in the fishery, we divide vessels into groups based on fishing patterns prior to the closure, and test for differences in total effort and in the likelihood of exiting the fishery. Our results contribute to an understanding of the relative magnitudes of two important effects of marine reserves – reduction in total fishing effort and redistribution of fishing effort. Effort redistribution affects the ability of marine reserves to achieve stock rebuilding objectives. In the multi-species California groundfish trawl fishery, effort redistribution may also shift fishing pressure to alternative target species in the areas remaining open to trawling.