Carbon, nitrogen and caloric content of eggs, larvae, and juveniles of the walleye pollock, <i>Theragra chalcogramma</i>

Abstract

Measurements of dry weight (wt), carbon (C), nitrogen (N) and calories were made on walleye pollock eggs (0.24 mg, 35.3% C, 8.3% N, and 4.6 kcal g −1 dry wt), larvae (0.16 g, 42.9% C, 11.1% N and 5.1 kcal g −1 dry wt) and juveniles (22.4 g, 47.2% C, 9.0% N and 5.6 kcal g −1 dry wt). For juvenile fish (9–360 g wet wt) the measured values were related to dry weight and Fulton's condition factor index (CFI) by regression models. The CFI was a better predictor of body composition than dry weight. As CFI improved from a minimum starvation level of 0.42 to a maximum of 1.16, body caloric content, percentage C, and the C/N ratio increased (kcal g −1 dry wt = 4.4 CFI + 1.7, percentage carbon = 49.7 CFI 0.5 , C/N ratio = 5.0 CFI + 0.9), while percentage N and percentage ash decreased (percentage N =−3.5 CFI + 12.1; percentage ash = 9.1 CFI −1.4 ). The results of this study suggest that seasonal C, N and caloric content of young pollock can be estimated from measurements of Fulton's condition factor index.