Relationships between maternal body size, condition and potential fecundity of four north-west Atlantic demersal fishes

Fecundity data for four species (American plaice Hippoglossoides platessoides, yellowtail flounder Limanda ferruginea, witch flounder Glyptocephalus cynoglossus and Atlantic cod Gadus morhua) of north-west Atlantic demersal fishes, corresponding to nine populations, were examined in relation to fish size and condition in an attempt to explain the observed variability in potential fecundity. Both relative body (K-r) and liver condition (H-r) were poor single-factor predictors of fecundity, and in almost all cases fish body mass (M) was the best single-factor predictor. Annual variability in mean K-r and H-r existed for most populations. The inclusion of K-r and H-r in total length (L-T)-based predictive models improved model fit only slightly and not significantly in all cases. Multiple regression analyses to determine the best model for explaining the variability in fecundity often excluded K-r, H-r and L-T in favour of M. The amount of variability in fecundity that could be explained by the factors analysed here was species specific, with the highest proportion explained for H. platessoides and the lowest for L. ferruginea. The highly variable, and sometimes unpredictable, nature of north-west Atlantic groundfish fecundity suggests the need to continue collecting such reproductive data on an ongoing basis.