EARLY-LIFE HISTORY AND RECRUITMENT PROCESSES OF CLAWED LOBSTERS

This review focuses on the larval, postlarval, and early benthic life of Homarus and Nephrops, the two best studied, and commercially most i mportant, genera of the Nephropidae. Processes acting during this time of the life cycle may be critical of the fate of a cohort. In the pas t decade, significant advances have been made in understanding events before and after settlement. Nephrops and Homarus are very similar wit h respect to the processes affecting the distribution of the pelagic l arvae and postlarvae: wind, currents and larval behavior play a signif icant role. Duration of the pelagic phase is determined by temperature , timing of settlement, and perhaps nutrition. Both genera probably ar e quite selective of substratum during settlement, but this has been i nvestigated only in Homarus, where substratum type, odor, and predator presence affect choice of habitat. The two genera contrast, however, with respect to some of the processes occurring during and after postl arval settlement. Although both are cryptic, newly settled Homarus are found in shallow, rocky habitats, while settled Nephrops are found in deep water, in burrows they construct in cohesive mud. Homarus underg oes a developmental change in behavior within the first few years of b enthic life that causes an increasingly wide range of movement; sexual ly mature H. americanus can move hundreds of kilometers in a year. Nep hrops emerges more as it grows, but appears to be far more sedentary t han Homarus. Thus in contrast to Homarus, a number of distinct populat ions of Nephrops exist within the species range that are clearly defin ed by habitat boundaries. New techniques now permit routine census and tagging of early benthic phase Homarus, making it possible to follow year classes from the time of settlement. It is the years immediately after settlement that a cohort may be subject to density-dependent con trols, a key issue facing workers on both groups.