Role of habitat in mediating mortality during the post‐settlement transition phase of temperate marine fishes

The transition phase describes a distinct post‐settlement stage associated with the recruitment to benthic habitats by pelagic life stages. The habitat shift is often accompanied by feeding shifts and metamorphosis from larval to juvenile phases. Density‐dependent settlement, growth and mortality are often the major factors controlling recruitment success of this phase. Habitat use also becomes more pronounced after settlement. The role of habitat‐mediated post‐settlement mortality is elucidated by focusing on the early life history of Atlantic cod ( Gadus morhua ) and cunner ( Tautogolabrus adspersus ) in the north‐west Atlantic. In these species, settlement can occur over all bottom types, but habitat‐specific differences in post‐settlement mortality rates combined with size and priority at settlement effects on growth and survival determine recruitment and eventual year‐class strength. These results and those from other temperate marine fish species along with work on tropical reef species emphasize the generality of habitat‐based density‐dependent mortality during the transition phase and its potential for population regulation. These results have implications for fisheries management and can be used to outline a procedure to assist managers in identifying and managing essential transitional habitats including the potential role of marine protected areas in habitat conservation.