Recruitment dynamics of bluefish (Pomatomus saltatrix) from Cape Hatteras to Cape Cod, 1973–1995

Abstract

Recruitment dynamics are complicated in species in which multiple cohorts of young-of-the-year (YOY) are produced each year. Each summer, two cohorts of YOY bluefish (Pomatomus saltatrix), representing fish spawned in spring and summer, recruit to Mid-Atlantic Bight estuaries, but little is known about their interannual variability, environmental forcing, and relative contributions to later life stages. We addressed these questions by examining the distribution and abundance of YOY on the continental shelf of the US east coast in autumn from 1973 through 1995. Abundance on the continental shelf increased in autumn owing to emigration from estuaries. We found clear evidence of two cohorts in autumn length-frequency distributions in most years and used this information to construct cohort-specific indices of abundance, which were then compared with relevant environmental variables. Spring-spawned fish dominated the catch in 20 of the years examined. The summer cohort dominated only in 1992. The abundance of the two cohorts was positively correlated, rejecting the hypothesis that dominance of the spring cohort is the result of cannibalism on the summer cohort. Spring cohort abundance was not correlated with either shelf warming-rate or warm-core ring streamer activity. A strong relationship was found between winds in April and May and the abundance of spring-spawned bluefish, possibly indicating that wind-driven surface flow aids the transport of larvae and/or juveniles across the shelf-slope region. 2000 International Council for the Exploration of the Sea