A Simple Growth Model for Salmonids in Hatcheries

Abstract

A simple growth model for salmonids in hatcheries was developed from several formulations presented in the literature. The model selected was Wt0.33 = W00.33 + (T/1000)t where Wt = weight at time t (g), W0 = initial weight, T = average temperature (°C), and t = time in days. The model was chosen from a number of possible formulations on the basis of its simplicity. Additional attributes are W0.33 is linear with time, the slope of the line W0.33 vs. time (termed growth slope) is linear with temperature (i.e. T/1000) over the temperature range commonly found in hatcheries that rear salmonids, and W0.33 is easily converted to length. Tests of the model on wild stock steelhead in British Columbia hatcheries provided good results under normal operating conditions of feeding, loading, etc. Applications of the model are also presented, including the development of a growth coefficient allowing comparisons of growth rate corrected for fish size and temperature effects.Key words: growth model, salmonids, fish culture