At this time minimum size limit regulations are the primary tool used to manage Rhode Island's American lobster (Homarus americanus) resource. One shortcoming of this policy is its lack of foundation in bioeconomic analysis. To encourage the incorporation of bioeconomic considerations into the management strategy used on this valuable resource, a fishery simulator (Gates 1974) was modified and employed to analyze the effects of changing the size at first capture in Rhode Island's inshore lobster fishery.

A cost and earnings survey of Rhode Island's commercial lobster license holders was conducted to provide the economic data required to simulate the fishery. This survey uncovered information characterizing the exploitation of the resource. For example, the survey estimated inshore catch of 2.1 million pounds indicates that three quarters of the inshore catch may go unrecorded. The survey also revealed that full-time commercial harvesters are outnumbered by part-time personnel by a factor of seven, but still land over 90% of Rhode Island's lobster catch.

The simulation results also proved quite informative. They suggest that an increase in Rhode Island's minimum size at first capture, if promulgated alone, will not confer increased benefits to society or fishermen. In fact, if a reasonable rate of discount is employed, the analysis indicates the measure will decrease the present value of social surplus generated by Rhode Island's inshore lobster fishery. Averaging over the range of results obtained, an 0.8 mm carapace length increase will reduce annualized benefits by 7%. Alternative larger increases of 1.6 mm and 9.5 mm (3.5 inch minimum) are estimated to bring about 10% and 38% reductions in the annualized value of social surplus that the inshore fishery can be expected to generate. These results are due in part to the substantial short run decreases in catch that the increased minimum sizes generate, and in part because it is assumed that the increased minimum size will govern Rhode Island's landings only.

The immediate short run decreases in benefits that accompany the minimum size increases were found to fall primarily on the harvesters of the resource. Averaging over the discount rates employed, 87% of the short run reductions in social surplus subtracted from producer revenues. All results assume that stock recruitment is independent of stock size, that stock reproductive security is not at issue, and that lobster prices are determined in a regional market for live lobsters.

Additional simulations were performed to compare the social surplus in the open access fishery with that which might be obtained should access to the fishery be restricted. Also, social surpluses were obtained for the fishery under the assumption that an increased size at first capture results in increased recruitment. These simulations point to the general result that increased harvest selectivity will maximize the sustainable fleet size while concurrently reducing the annual social surplus generated by the fishery.