A persistent challenge of managing capture fisheries is assessing and managing for fisheries-related mortality. Fisheries-related mortality can include loss due to derelict gear, detrimental handling of organisms, and poaching (reviewed in (23). Additionally, harvest of species can cause shifts in sex-ratios or can impact the genetic structure of a population due to harvest size limits (34). In order to minimize potential impacts of harvest to an exploited population, it is essential to fully understand the potential impacts that management strategies can have on the stock.
Dungeness crab is a highly exploited species, with 95% of legal sized males removed by harvest annually (CITATION). The fishery is managed to avoid harvest during molting, however, the PCRG is interested in understanding the drivers of molt timing to determine if they will change in the future (Table XX). In order for mating to be successful between a recently molted female and male, the male has to be larger than the female. Because large males are targeted by the fishery, there is concern that this can lead to sperm limitation and skewed sex ratios in Dungeness crab populations and warrants updated investigation (35). This skewed sex ratio could result in loss of egg productivity and limit population abundance in the future due to intensive harvest.
The mortality of crab due to derelict gear is well studied (36), however, the PCRG noted that there has been little done to research the best methods of changing recreational fisher behavior. Changing behavior could lead to the reduction of lost traps, saving both monetary resources to remove them and reducing the loss of Dungeness crab. Related to behavior, is the presence of poaching in Washington state. In order for management to be effective, it relies on the compliance of individuals to regulations. However, poaching is difficult to assess, given its illegal nature (37).
Collaborative research efforts have been successful in other fisheries to reduce fisheries-related mortality, either for reducing bycatch or handling impacts (38). The PCRG can address information gaps and assist in formulating suggestions to reduce mortality and population structure impacts that can inform co-managers in their decision-making in the future.