Recruitment to American Lobster Populations along an Estuarine Gradient

This study evaluates patterns in the distribution and abundance of newly recruited (young-of-the-year) and older American lobster (Homarus americanus Milne Edwards) along a 22 km length of the Narragansett Bay estuary, Rhode Island, with particular attention to substratum associations. This not only represents the first assessment of benthic recruitment of this species along an estuary, but it is also the first study of lobster recruitment in southern New England. Censuses were conducted by divers in a substratum-specific manner. In cobble-boulder habitat, with the aid of a diver-operated suction sampler, I found newly recruited (5-10 mm carapace length) lobsters to be most abundant on the open coast, with numbers diminishing to zero in the upper bay. Visual censuses of older lobsters in the same habitat revealed a similar pattern. On featureless sedimentary habitats new recruits were absent and lobster densities were at least two orders of magnitude lower than in rocky habitats. In Narragansett Bay, rocky habitats comprise a small proportion of the bottom. The availability of such habitats, the relative importance of larval supply and potential physiological stress in limiting recruitment up-bay remain unclear.