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Fisheries Behavioral Ecology - Abstracts

Hurst, T.P., B.J. Laurel, L. Ciannelli. 2010. Ontogenetic patterns and temperature-dependent growth rates in early life stages of Pacific cod (Gadus macrocephalus). Fish. Bull. 108:382-392.

Abstract

Pacific cod (Gadus macro­cephalus) is an important component of fisheries and food webs in the North Pacific Ocean and Bering Sea. How­ever, vital rates of early life stages of this species have yet to be described in detail. We determined the ther­mal sensitivity of growth rates of embryos, preflexion and postflexion larvae, and post settlement juveniles. Growth rates (length and mass) at each ontogenetic stage were measured in three replicate tanks at four to five temperatures. Nonlinear regression was used to obtain parameters for independent stage-specific growth functions and a unified size- and tem­perature-dependent growth function. Specific growth rates increased with temperature at all stages and gener­ally decreased with increases in body size. However, these analyses revealed a departure from a strict size-based allometry in growth patterns, as reduced growth rates were observed among preflexion larvae: the reduc­tion in specific growth rate between embryos and free-swimming larvae was greater than expected based on body size differences. Growth reduc­tions in the preflexion larvae appear to be associated with increased meta­bolic rates and the transition from endogenous to exogenous feeding. In future studies, experiments should be integrated across life transitions to more clearly define intrinsic onto­genetic and size-dependent growth patterns because these are critical for evaluations of spatial and temporal variation in habitat quality.

 

 

Last updated 11 January, 2011


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