A bio-economic analysis of a shell fishery: The effects of recruitment and habitat in a meta population model

This paper presents a bioeconomic model where fishing effort exerted has multiple impacts on the recruitment process of a sedentary shellfish population. Recognizing that sedentary populations generally possess metapopulation characteristics at the recruitment stage, we show that fishing effort exerted not only influences the recruitment process indirectly by limiting the number of adults that spawn, but also directly by affecting the habitat in which shellfish larvae recruit. Depending on the recruitment characteristics, fishing can have negative and positive direct and indirect effects on the recruitment process. Next, a positive direct effect that fishing can have on the growth rate of the shellfish population if space to recruit to is limited is studied. General characteristics of sustainable fishing are analyzed for the case that recruitment occurs immediately once spawning has occurred as well as for the case that recruitment takes place over a longer period of time. Conditions are identified under which shellfishing should be encouraged in order to facilitate the recruitment process of juveniles. The paper ends by analyzing how fishing alters the optimal sustainable solution when it contributes to habitat destruction.