Inter-cohort differences in spatial and temporal settlement patterns of young-of-the-year windowpane (Scophthalmus aquosus) in southern New Jersey

The timing and location of settlement of two cohorts (spring and fall) of windowpane (Scophthalmus aquosus) were identified based on collections from 64 sampling locations along a corridor from the lower estuary, through the inlet, and on to the adjacent inner continental shelf in southern New Jersey. Spatio-temporal patterns of settlement during 1989–1998 were determined based on capture location and timing, and eye migration stage. Spring-spawned windowpanes were collected in estuarine, inlet and ocean habitats as larvae, during settlement, and after settlement. Densities of spring-spawned larvae ( 2–10mm standard length (SL)) peaked in May in all habitats (estuary, inlet, and ocean). Initial settlement of spring-spawned windowpane occurred during May in the inlet and ocean when fish had grown to 7–8mm SL (mid-point of eye migration), but fish did not appear in demersal estuarine collections until June when they were larger and more developmentally advanced ( 24–32mm SL; post-eye migration). A transitional settlement period, comprised of a progressive habitat shift from pelagic to demersal habitats, is proposed for the spring cohort to explain the observed patterns. Fall-spawned fish of all developmental stages and sizes were virtually absent from estuarine collections. Fall-spawned larval ( 2–10mm SL) densities peaked in October in inlet and ocean habitats and fish began settling there during the same month at sizes similar to the spring cohort ( 7–8mm SL). This research confirms that there are important cohort-specific and life-stage dependent differences in young-of-the-year (YOY) windowpane habitat use in southern New Jersey and perhaps in other east coast US estuaries. These differences may affect the overall contribution that each cohort makes to a given year class and thus, may have an important role in determining the recruitment dynamics of this species.