Number of meals in a day, maximum weight of food consumed in a day and maximum rate of feeding for brown trout, Salmo trutta L.

Abstract

Summary: Brown trout (live weight 9–302 g) were fed to satiation in each of four meals at seven different water temperatures (range 3.8–18.1°C). The period (I h) from the start of one meal to the start of the following meal was not significantly affected by the weight (Wg) of the trout, but was negatively correlated with water temperature (T°C). A regression equation described the exponential relationship between I and T, and also estimated the number of meals {N) in a day. Values ranged from one meal at about 4°C t o three meals at about 18°C, The greatest increase in appetite occurred at the end of the period I. The maximum weight offood (D rng) eaten in a day was positively correlated with both W and T, a relationship which was well described by a multiple regression equation. The maximum rate of feeding (F mg h−1) was not significantly affected by W, but increased from 3.8 to 6.8°C, was fairly constant from 6.8 to 19.3°C, and decreased markedly above 19.3°C. Estimates of D and F(with 95% confidence limits) were applicable to a wide variety offood organisms with the exception of mealworms. From comparisons with the results of other workers, it was concluded that the upper limit ofthe daily energy intake determines the optimum temperature for growth.