Fishery management in data-limited situations: Applications to stock assessment, marine reserve design and fish bycatch policy.

摘要

In 1996, the United States Congress updated the Magnuson-Stevens Fishery Conservation and Management Act through the Sustainable Fisheries Act (SFA), which calls for the minimization of bycatch, an attention to efficiency, and the use of the best available science. My work addresses those demands in three distinct ways.; First, life history parameters of stock assessment models must be estimated using either statistical tools or functional forms based on physiological or ecological theory. I use Bayesian methods to fit the parameters of the von Bertalanffy growth equation (VBGE), a function used to model individual growth, and the instantaneous natural mortality rate, M. I also develop a Bayesian model to find asymptotic size from the VBGE without size-at-age data. Life history theory provides a number of ways to calculate natural mortality. I test these methods on both simulated and real data. In general, weight- and age-based methods provide very different estimates for the same data than the methods based on individual growth rate and age at maturity.; Second, the effectiveness of fishery management is judged both by the abundance of stocks and the continuing yield for fishers. Marine reserves are in the limelight of fishery management as a potential panacea for management, but analyses of the fishery effects of marine reserves are sparse. I review the literature for specific fishery benefits of reserves designed for a single or multispecies effect. I find little consensus on larval export, spillover, or density dependent mechanisms and their effect on fisheries outside the reserve.; Third, the SFA calls for the immediate minimization of bycatch, and when practicable, that the mortality of that bycatch be minimized. I address this question by conducting an analysis of bycatch policy. I focus on the fish component of bycatch and I review the implementation and the effectiveness of various bycatch policies in the United States. Such policies require the use of bycatch reduction devices (BRDs), time/area closures, and gear modifications.