Parameterizing an expanded square root model to account for the effects of temperature, meal size, and body size on gastric evacuation rate in farmed brown trout

Abstract

Gastric evacuation rate (GER) modelling is a promising tool for planning feeding regimes to optimize farmed fish growth and minimize feed waste. This study examined the influences of the predictor variables viz. temperature, meal size, and body size on GER of farmed brown trout (Salmo trutta L.) fed commercial pellets in GER experiments. The experiments included large fish of 29.3 ± 0.3 cm (mean ± SE, total length) and 280.8 ± 7.8 g (wet weight) fed meals of 2 g and 6 gas well as small fish of 15.1 ± 0.1 cm and 33.9 ± 0.7 g fed meals of 0.3 and 0.8 g. The water temperature ranged from 13.0 to 19.2°C. The square root model best described GER independently of meal size. The influence on GER of the two other predictor variables was then quantified using a simple power function for body size and an exponential for temperature. The statistical analyses provided the relationships (g/h) and (g/h), where St is the current stomach content mass (g), W the body mass (g), L the total body length (cm), T the temperature (°C), and t the time (h). These findings should enhance the effectiveness and efficiency of feeding strategies to optimize growth, minimize expensive feed wastes, and reduce environmental pollution caused by aquaculture.