SIZE, GROWTH, DEVELOPMENT, AND SURVIVAL OF THE PLANKTONIC LARVAE OFPOMATOMUS SALTATRIX(PISCES: POMATOMIDAE)

Abstract

A variety of hypotheses have been proposed regarding the processes that regulate survival of the planktonic life history stages of marine organisms. Several of these hypotheses have been grouped under a general, “growth–mortality” hypothesis, which postulates that larger (a “bigger‐is‐better” mechanism), faster growing (a “growth‐rate” mechanism), and faster developing (a “stage‐duration” mechanism) individuals have a higher probability of survival. Using the otolith record of age, size, and ontogeny, these three mechanisms of the “growth–mortality” hypothesis were tested for the larval and pelagic juvenile stages of bluefish, Pomatomus saltatrix (Pisces: Pomatomidae), a moderate‐sized, coastal, pelagic, marine fish. Individuals that were larger‐at‐age were found to have a higher probability of survival, supporting the “bigger‐is‐better” mechanism. Faster growing individuals were also found to have a higher probability of survival, agreeing with the prediction of the “growth‐rate” mechanism. Equivocal evidence was found with regard to the “stage‐duration” mechanism. These results suggest that in pelagic ecosystems, larger and faster growing larvae have a higher probability of survival. Given the observed directional selection acting on larval size and growth, several potential mechanisms that maintain variable larval size and growth are addressed. Finally, the growth‐related processes examined in this study are discussed in the context of the physical aspects of pelagic ecosystems that may also affect larval survival.