Effects of habitat on settlement, growth, and postsettlement survival of Atlantic cod (Gadus morhua)

Settlement and growth of age 0+ cod were monitored in four distinct habitat types (sand, seagrass, cobble, and rock reef) in St. Margaret's Bay, Nova Scotia. Settlement of cod did not differ between habitat types, but postsettlement survival and subsequent juvenile densities were higher in more structurally complex habitats. These differences appear to be due to increased shelter availability and decreased predator efficiency in structurally complex habitats. Growth rate was highest in seagrass beds, while the efficiency of cod predators was lowest and cod survival was highest on rocky reefs and cobble bottoms. Thus, trade-offs occur between energy gain and predation risk. In St. Margaret;s Bay, the population structure of Atlantic cod may be less influenced by patterns of larval supply than by postsettlement processes such as habitat-specific growth and mortality.