The Effects of Abiotic and Biotic Factors in Determining Larval Fish Growth Rates: A Comparison Across Species and Reservoirs

Abstract

Understanding the processes that underlie larval fish growth are important in predicting recruitment. However, the factors and mechanisms that influence early life stages of fishes are complex and not well understood. We evaluated the role of several abiotic and biotic factors in determining larval fish growth rates across 21 Illinois reservoirs. Larval crappies Pomoxis spp., sunfish Lepomis spp., and gizzard shad Dorosoma cepedianum were collected by push nets from May through July in 1995. Lakes were classified based on morphometric, limnological, and biotic variables using principal components analysis (PCA). In general, the abiotic variables loaded highest in PCA and explained the most variation across reservoirs. The relationships between larval fish growth, using otolith daily rings, were then examined with the principal components and by multiple regression. Larval fish growth rates were highly variable across reservoirs. Mean growth was lowest, but the range of growth rates were highest for crappie and bluegill; growth rates of larval gizzard shad were higher but less variable across reservoirs. Abiotic variables such as latitude, lake temperature, and characteristics of lake size were important in explaining growth for all three species. The relationships between larval fish growth rates and biotic variables, such as zooplankton and larval fish densities, were more species specific. By comparing across a number of reservoirs with a multivariate approach, we were able to generate an understanding of the complex interactions between abiotic and biotic variables that influence larval fish growth rates.