An indicator-based decision framework for the northern California red abalone fishery

Among abalone species that were once harvested along the California coastline, red abalone (Haliotis rufescens) supports the remaining recreational fishery. To support development of a red abalone fishery management plan, non-governmental organizations have initiated expanded data collection and developed fishery management strategies. The latter is the subject of this study, as we present a management strategy evaluation (MSE) of a multi-indicator decision tree. The decision tree relies on landings from each of 56 fishing sites and length frequency information collected during fishery-independent diver surveys at a subset of sites. The decision tree was designed to cope with existing data limitations and to ensure that localized meta-population dynamics were adequately considered in decision-making. It was also necessary to balance the potential for localized abundance changes with the practical issue of implementing fishery regulations at larger spatial scales. The MSE demonstrated that undesirably low stock sizes could be avoided while also continuing to maintain a viable fishery, even under environmental conditions that are detrimental to abalone populations. Under less-severe environmental conditions, stock size was maintained, on average, above the biomass associated with production of maximum sustainable yield. Our discussion centers on steps that were taken to refine the decision tree and to incorporate feedback from scientists and stakeholders and to facilitate transparent evaluation of management options.