Seasonal Energetics and Condition of Bonefish from Different Subtropical Tidal Creeks in Eleuthera, the Bahamas

Body composition and fish health indices of bonefish Albula vulpes were investigated to elucidate the energy dynamics in poorly studied tropical tidal flat environments. In general, bonefish were composed of 72%% water, 21%% protein, 4%% ash, and 3%% lipids, which is consistent with the wet weight values of the majority of freshwater and marine fish studied to date. Significant inverse relationships between the water and lipid contents of whole-body, gonad, and liver tissues revealed that the percentage of water is a good indicator of the relative amount of stored energy in bonefish and may be used as a surrogate for lipid content in future studies. The liver was the main storage site for lipids, containing more than twice the fat in the whole body. While both abiotic (e.g., season and location) and biotic (e.g., sex and size) factors contributed to the predictive power of the general linear models generated for all constituent analyses, there were no significant differences in whole-body or liver lipid content between seasons, which may be explained by there being a consistent food supply year-round. There was, however, a significant relationship between lipid content and body size with respect to season. Lipid content decreased in the winter and increased in the summer with increasing body size, a trend that can be explained by the timing of the reproductive season in bonefish. Seasonal changes in the condition factor and gonadosomatic indices were also linked to the winter spawning season, with decreasing body condition and increasing gonad development in the winter. Observed site-specific differences in the lipid content and liver somatic indices of bonefish may be accounted for by local trophodynamics as well as subtle differences in life history strategies. The energy reserve and fish health index data collected in this study may provide a useful baseline for future comparative work and help elucidate fish energetics in dynamic tropical tidal flat systems.