AN ANALYSIS OF SUBSTRATE SELECTION BY POSTLARVAL AMERICAN LOBSTERS, HOMARUS-AMERICANUS, USING A DYNAMIC OPTIMIZATION MODEL

During the fourth stage of larval development the American lobster (Ho marus americanus) leaves the plankton and becomes benthic. Before fina l settlement lobsters sample different substrates which may be accepte d or rejected. Upon rejection the lobster returns to the plankton befo re sampling another substrate. In this paper we present a model of the substrate selection behavior of settling lobsters using dynamic optim ization techniques. The model examines the role of substrate quality a nd availability, postlarval testing of substrates, and mortality assoc iated with testing substrates, upon the decision to accept or reject t he substrates sampled and predicts the eventual importance of each sub strate in the recruitment of lobsters to reproductive age. Finally we apply the model using recent data on long-term survival of lobsters in the field. The model predicts that the high quality substrate (cobble ) accounts for most of the adult lobster population, in spite of the m uch greater abundance of other, more marginal, substrates.