Ontogeny of energetic relationships and potential effects of tissue turnover: a comparative modeling study on lake trout

Tissue turnover is endogenous energy flow and may play a regulatory role in the metabolic system of an organism. We developed a general growth model a ddressing potential effect of tissue turnover on energy acquisition and par titioning. We applied the model to estimate energy assimilation of lake tro ut (Salvelinus namaycush) in Lake Michigan and compared the model with a co mmonly used complex model. Both models are expansions of the Putter von Ber talanffy growth model. The new model suggested a consistent decreasing tren d in energy net conversion efficiency (NCE) for somatic growth versus body energy. The complex model suggested that NCE is relatively stable in early ages and decreases slowly in comparison with the pattern suggested by the n ew model. The new model estimated higher specific assimilation rate and NCE for gonadal growth than for somatic growth of mature fish. The complex mod el did not distinguish gonadal growth from somatic growth. For a lake trout growing from the start of age-1 to the end of age-10, our new model sugges ted a total energy assimilation 25% higher than the complex model. The abov e comparisons support the inference that tissue turnover is an important bi oenergetic component. Inclusion of tissue turnover in bioenergetic modeling analyses may be critical for studying the linkages among individual growth , reproduction, and population dynamics.