Rapid morphological divergence of cultured cod of the northwest Atlantic from their source population

Abstract

The performance of aquaculture escapees in the wild depends in part on how their morphology differs from that of wild fish. We compared farmed Atlantic cod Gadus morhua morphology to that of wild cod from the same ancestral population. Traditional and geometric morphometrics showed that farmed cod had relatively smaller fins, heads, eyes, and jaws than wild cod for a given size. Conversely, drumming muscle size and metrics of body and liver condition were greater in farmed fish. As the observed differences are likely due to phenotypic plasticity, their fitness consequences for escaped farmed fish may be transient.