Patterns and trends in larval-stage growth and mortality of teleost fish*

Authors


  • *

    The sixth J. W. Jones lecture. Tel: +1 410 326-7224; fax: + 1 410 326-7318; email: ehoude@cbl.umccs.edu

Abstract

Weight-specific growth (G) and instantaneous mortality (M) rates are linked processes during early life, and the MIG ratio determines stage-specific mortality. A comparative analysis of five species identified patterns and trends in larval M and G, and their relationship to variability in larval cohort abundance. M declined with respect to body size in all species, although levels of M were variable between taxa and years. Rates of decline in M with respect to size generally were higher than predicted by size-spectrum theory. G varied between species and years, but was less variable than M. In some species (e.g. striped bass and American shad) G increased appreciably before declining, while in others G declined throughout the larval stage. Consequently, stage-specific mortality, which is governed by MIG and body size, declined slowly or was relatively constant throughout the larval stage. Cohort biomass declined during the early larval stages. and began to increase only when larvae attained the ‘transition size’ at which MIG < 1.0. Annual variability in transition sizes and ages, which is a consequence of trends, patterns, and variability in MIG, can act to control recruitment. Mortality is growth-dependent and growth-related factors are correlated with recruitment potentials, but measures of larval growth alone are not sufficient to predict or explain variability in recruitments.

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