| Summary: | The energy content obtained from the diets of American plaice (Hippoglossoides platessoides) in the Grand Bank and the Flemish Cap was estimated from the feeding composition of 6570 and 1290 individuals, respectively, sampled in spring-summer in the 2002-2006 period. This was related to the reported growth and longevity of this fish species in each area. To estimate energy values of food components, the daily ration for American plaice in the Grand Bank was calculated using Elliot and Persson, Eggers, and Swenson and Smith Models. Results showed differences among models, the values obtained with the first two models were the closest; the third model gave higher values. Daily ration was higher in females and it increased with length. The values ranged between 1.61 to 2.24%BW/d in females and 0.54 to 4.18%BW/d in males with the Elliot & Persson model. Results showed that the Flemish Cap diet had higher energy, and that the female diet was richer in energy in both areas. Differences in the energy component of the diet between areas decreased with increasing length for both sexes; it was linked to a diet change of the individuals in the Grand Bank from a length of 34 cm in males and 51 cm in females. This result agrees with the differences in growth and longevity observed in each area for both sexes. The influence of feeding on populational differences could be reflected. The observed trend of diminishing energy differences between areas where the individuals are >30 cm is even more marked in the biggest individuals. This would agree with the superior growth rate in the Flemish Cap, at the same time as a smaller Lmax and longevity. The sizes where the growth pattern changes are close to those where the feeding pattern also changes.
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