The use of marine reserves in evaluating the dive fishery for the warty sea cucumber (Parastichopus parvimensis) in California, U.S.A.

Management of sustainable fisheries depends upon reliable estimates of stock assessment. Assessment of many stocks is based entirely on fishery-dependent data (e.g., catch per unit effort), which can be problematic. Here we use fishery-independent data on stock size, collected within and outside of no-take reserves before and after the onset of fishing, to evaluate the status of the dive fishery for warty sea cucumbers, Parastichopus parvimensis, in southern California. Long-term monitoring data showed that abundance decreased throughout the Channel Islands within 3–6 years after the onset of fishing. No significant changes in the abundance of P. parvimensis were observed at the two non-fished reserve sites, although densities tended to increase following onset of the fishery. Before–after, control–impact (BACI) analyses of seven fished and two non-fished sites implicated fishing mortality as the cause of 33–83% stock declines. In sharp contrast, stock assessment based on CPUE data showed no declines and a significant increase at one island. To date, most discussion on marine reserves has focused on the protection and enhancement of exploited populations. Our study demonstrates the critically important, but often overlooked, role that marine reserves can play in providing reliable information on stock assessment.