Optimal exploitation of Atlantic herring stocks in United States of America: Bioeconomic model for Atlantic herring (Clupea harengus).

摘要

The Atlantic herring, Clupea harengus, is a pelagic species widely distributed in continental shelf waters along the Atlantic coast from the Gulf of Maine to Cape Hatteras. Even though the herring fishery is a relatively small portion of the East coast fishing industry, herring is important as bait for lobster fisheries and a component of the food web of the Northwest Atlantic Ocean. Currently, the herring resource is in an under-exploited state and catches are less than one-third of Maximum Sustainable Yield. The herring fishery is reviewed in term of markets, resource, and management. Because herring is very vulnerable to environmental variables, it is hypothesized that egg and larval stage herring are very sensitive to low temperatures. The correlation and regression between temperature and two year-old recruitment stock was analyzed. The results suggest that environmental factors are significant in the production model for a fishery, and their inclusion is necessary to understand the cycle of fluctuating stock.; Ecosystem reserves (ER) in the context of the Atlantic herring fishery was discussed. A reduction in the TAC for the purpose of increasing the residual stocks available to other species in the ecosystem, I refer to as “Ecosystem Reserves” (ER). An increase in ER may imply reduced benefits of commercial harvest. In return for this reduction, we calculate added benefits for the ecosystem from the ER. The approximate magnitudes of these two components—Reduced Benefits and Added Benefits—are estimated. It must be admitted at the outset that the information at our disposal is very partial and, while our estimates are illustrative of method, their precision leaves much to be desired. Improved precision is always possible but requires a judgment of the value of increased precision versus cost. In particular, if policy decisions are insensitive to the precision of estimates, increased precision, whatever its scientific or methodological merit, has no current decision value, although it may become valuable in the future as circumstances and facts change. A basic bioeconomic model is reviewed, and a bioeconomic model for Atlantic herring is developed. Using scenario-dependent sensitivity analyses optimal exploitations were estimated, and compared in terms of stock size, harvest, and present value of net profit. These results will provide an optimal reference point to herring resource manager and policy makers.