Optimum temperature for growth of juvenile walleye pollock Theragra chalcogramma

Abstract

Food consumption (FC), specific growth rate (SGR), and gross growth efficiency (GGE) were measured for juvenile walleye pollock (initial size 112–153 mm fork length) fed euphausiids at temperatures ( T) between 2 and 16 °C. FC increased up to 12 °C (7.3% of body weight) and was slightly lower at 16 °C. SGR also increased up to 12 °C (2% d − 1 ) but rapidly decreased at 16 °C. The optimum temperatures for FC and SGR were 12.3 °C and 11.5 °C, respectively. GGE was similar (27.3–29.9%) for temperatures in the range of 2–9 °C and decreased at higher temperatures. GGE in terms of energy (GGE = − 1.37 T + 38.41) and the energy density of fish was higher at lower temperatures, suggesting that residence of juvenile pollock in cold water induces energy storage. In the Doto continental-shelf area, juvenile pollock were distributed over a wide range of temperatures (5.4–15.0 °C) during the summer. This suggests that factors other than water temperature may affect the summer distribution of juvenile pollock, although temperature would be the most important factor in a food-unlimited environment.