The interrelationship of temperature, growth parameters, and activity level in fishes

This study presents a multiple regression of the parameter K , i.e., the rate at which the asymptote of the von Bertalanffy Growth Function (VBGF) is approached vs. the asymptotic weight ( W ∞ ), environmental temperature ( T’ ), and an index of activity level (the aspect ratio of the caudal fin, or A) in 4251 populations and 1155 fish species extracted from FishBase ( www.fishbase.org ). The resulting model was log( K ) = 3.674 − 0.2362·log( W ∞ ) − 1.035· T’ + 0.2838·log( A ), with K in year −1 , W ∞ in g, and T’ = −1000/Kelvin. It explained 57 % of the variance in the dataset, with all partial slopes significantly different from zero ( p < 0.01), and having the expected signs. Thus, temperature decreases the asymptotic size of fish, but increases their parameter K , and thus decreases traits associated with K , e.g., longevity. Also, our model suggests that A , which take values around 1 in less active fish such as groupers and 8–9 in active swimmers such as tuna, correlates with K values. This implies that active fish have large gill areas supplying the oxygen required for both a high level of activity and rapid growth, both supported by a high feeding rate, which is what we know of these fishes.