Seasonal Consumption by Dace (Phoxinus eos × P. neogaeus): A Comparison between Field and Bioenergetic Model Estimates
We compared the predictions of two bioenergetic models with independent field-derived estimates of consumption rates for dace (Phoxinus eos × P. neogaeus). These two models differ only in the energy that fish allocate to standard metabolism and activity. Daily ration and body mass of age 3+ dace from Lake Triton were estimated on 29 occasions during a 67-d period (June 22 – August 27, 1992). Water temperature and caloric density of fish and food were also monitored. Fish growth was on average 2.5 cal∙d−1 (1 cal = 4.19 J). Observed cumulative consumption for an average fish was 7.6 kcal. Seasonal consumption predicted by the first and second models was 33.5 and 6.5 kcal, respectively. The prediction of the second model was not significantly different from our direct estimate. The second bioenergetic model can be used to accurately predict the feeding rate of dace in the field by using models of maximum standard respiration (MSR) currently available in the literature (intercept = 0.015, slope = −0.2) with an activity multiplier of 1. Alternatively, because these models often include energy expenditures associated with digestion and/or activity, a MSR model having an intercept of 0.006 with an activity multiplier of 3 can also be used.