Lewis S. Incze and Kevin M. Bailey

ABSTRACT

Oceanographic conditions can give rise to areas of retention or recirculation of planktonic stages or they may lead to drift patterns with characeristic length scales and direction. Adult spawning behavior and other life history traits interact with these conditions, presumably through selection, to establish temporal and spatial patterns of spawning that favor survival. If spawning and recruitment occur within an area loosely bounded by the dispersion of planktonic stages and the migratory range of vagile stages, then a "local stock" or demographhic unit may develop. We may or may not be able to identify the stock as genetically distinct from the rest of the population even if it appears to be demographically distinct. Reasons include gene flow between spatial domains of different local stocks or failure, thus far, to identify appropriate markers. At smaller spatial scales, such as in a series of coastal embayments or closely-spaced offshore banks, local stock distinctness may be difficult to argue on an oceanographic basis, yet, it is possible that some degree of genetic distinctness exists. Thus, scientific insights into population structure and ecology require the integration of oceanography, demographic studies, behavior and genetics. The possible genetic influence on local adaptation(s) of a species has implications for management of the localized stock, including the possibility that it may not be readily replaced once gone.