RECRUITMENT OF YOUNG-OF-THE-YEAR BLUEFISH POMATOMUS-SALTATRIX TO THE NEW-YORK BIGHT - VARIATION IN ABUNDANCE AND GROWTH OF SPRING-SPAWNED AND SUMMER-SPAWNED COHORTS

The bluefish Pomatomus saltatrix spawns offshore in continental shelf waters and juveniles migrate to near-shore or estuarine waters during their first growing season. In estuaries of the New York Bight during 1987 and 1988, young-of-the-year bluefish appeared in 2 discrete size groups. Otolith analyses confirmed that the 2 groups originated from distinct spring and summer spawning periods. The spring-spawned cohort first recruited to estuaries in early to mid-June, whereas the summer-spawned cohort first recruited in middle to late August. In contrast with previous years when only spring-spawned fish were abundant, the overall abundance of spring vs summer cohorts was similar. There were, however, significant differences in abundance among bays that depended on cohort. Much of this variation in abundance is probably caused by variation in advective transport of larvae from spawning grounds to estuaries. Growth patterns differed substantially between the 2 cohorts. Spring-spawned bluefish grew slower than summer-spawned bluefish during the pre-recruitment oceanic phase of the early life history, perhaps because their northward transport causes them to encounter lower temperatures during the larval period. Both cohorts grow rapidly after estuarine recruitment, but spring-spawned bluefish are much larger than summer-spawned bluefish at the onset of fall migration. Overall year-class strength of bluefish along the US mid-Atlantic coast is a function of the combined recruitment success of the spring and summer cohorts.