Influence of the Size of Enclosures on the Swimming Characteristics of Juvenile Brook Trout (Salvelinus fontinalis)
We tested the hypothesis that swimming characteristics of an active planktivorous fish, brook trout (Salvelinus fontinalis), are significantly influenced by the size of enclosure and the time of day. Swimming characteristics of 0+ brook trout kept in 1,- 8,- and 27-m3 enclosures were recorded with an underwater videocamera system between 06:00 and 20:00. Enclosure size had a significant influence on swimming characteristics. Median speed (range = 6.4–11.1 cm/s) and associated variance observed in the 27-m3 enclosure were approximately twice those estimated in the 1- and 8-m3 enclosures. Variance of acceleration rates varied three- to fourfold among enclosures. Median turning rates (range = 11.8–19.8°/s) and corresponding variances tended to decrease as enclosure size increased. Our analyses suggest that models of spontaneous swimming costs developed using respirometry experiments performed in small aquaria may not appropriately represent the complexity of swimming patterns, and consequently, the costs of spontaneous swimming in large enclosures or in the field.