Abstract
A major challenge for small-scale fisheries management is high spatial variability in the demography and life history characteristics of target species. Implementation of local management actions that can reduce overfishing and maximize yields requires quantifying ecological heterogeneity at small spatial scales and is therefore limited by available resources and data. Collaborative fisheries research (CFR) is an effective means to collect essential fishery information at local scales, and to develop the social, technical, and logistical framework for fisheries management innovation. We used a CFR approach with fishing partners to collect and analyze geographically precise demographic information for grass rockfish (Sebastes rastrelliger), a sedentary, nearshore species harvested in the live fish fishery on the West Coast of the USA. Data were used to estimate geographically distinct growth rates, ages, mortality, and length frequency distributions in two environmental subregions of the Santa Barbara Channel, CA, USA. Results indicated the existence of two subpopulations; one located in the relatively cold, high productivity western Channel, and another in the relatively warm, low productivity eastern Channel. We parameterized yield per recruit models, the results of which suggested nearly twice as much yield per recruit in the high productivity subregion relative to the low productivity subregion. The spatial distribution of fishing in the two environmental subregions demonstrated a similar pattern to the yield per recruit outputs with greater landings, effort, and catch per unit effort in the high productivity subregion relative to the low productivity subregion. Understanding how spatial variability in stock dynamics translates to variability in fishery yield and distribution of effort is important to developing management plans that maximize fishing opportunities and conservation benefits at local scales.
Highlights
Biological parameters used to manage harvested marine fishes include such life history characteristics as age at maturity, size at age, and fecundity, as well as demographic rates such as growth, and mortality
We found that subtle changes in life history and demographic rates across small spatial scales can translate to large differences in yield per recruit (YPR)
During a series of meetings with our commercial fishery partners, we developed a testable hypothesis to explore whether higher landings in the high productivity subregion relative to the low productivity subregion are supported by spatial differences in life history and demographic rates between the two subregions
Summary
Biological parameters used to manage harvested marine fishes include such life history characteristics as age at maturity, size at age, and fecundity, as well as demographic rates such as growth, and mortality. Conventional approaches to managing nearshore fisheries often ignore spatial variability in life history characteristics and demographic rates, and instead pool these attributes across broad geographic scales [4]. The failure to account for such spatial variability may present a mismatch in the spatial scale of ecological dynamics and management actions for many nearshore fisheries [5,6,7]. This mismatch in scales can lead to underutilization and localized depletions of populations [8], often contributing to stakeholder discontent and reduced ecosystem integrity. The transition to and widespread acceptance of spatial management approaches in part depends on our ability to identify variable life history and demographic rates within and between populations, and to do so in a cost-effective manner
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
