Egg production by the bay anchovy Anchoa mitchilli in relation to adult and larval prey fields

Abstract

Abundances of copepod nauplii, copepodite/adult copepods, and the larvae of iteroparous anchovies [primarily the bay anchovy Anchoa mltchllli) were monitored in Tampa Bay, Florida (USA) at 2 wk intervals for 2 yr. All possible pairings of the 3 time-series variables yielded significant positive correlations. Nearly all (>98%) of the collected anchovy larvae occurred with prey (nauplius) densities higher than those reported to affect larval starvation (<l00 1-l). The larval association with abundant prey could be explained as (1) the remnants of earlier larval starvation, or (2) spawning being concentrated in zooplankton-rich waters. To evaluate the 2 explanations, the diet of adult A. mitchilli was analyzed, and egg/adult prey surveys were conducted across a 290 km2 area of Tampa Bay. In 5 of the 6 spatial surveys. A. mitchilli egg abundance was correlated with the abundance of calanoid copepods, a principal adult prey ~t e m .