Gastric Evacuation in Walleye Pollock, Theragra chalcogramma

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Abstract
The effects of meal size and temperature on food evacuation in juvenile walleye pollock (Theragra chalcogramma) were examined. In the range of meal sizes used (0.5-2.5% of body weight), food evacuation was a negative, exponential function of time. Increasing meal size reduced instantaneous evacuation rate but increased the amount of food evacuated. In the range of temperatures used (3-9.degree.C), both instantaneous evacuation rate and amount of food evacuted were positive linear functions of temperature. Our evacuation rate values are higher than previous estimates for walleye pollock, suggesting that daily ration and the trophic impact on prey species may have been significantly underestimated.