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

Abstract

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 densitydependent 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.

Quantifying fish and mobile invertebrate production from a threatened nursery habitat

“…Assuming the supply of larvae does not limit population size (see review by Caley et al . ), nursery habitats can mediate the population dynamics of enhanced fish (Juanes ). Recognition of this important function of structured habitats and their role as foraging areas for older age classes of fish has resulted in efforts to protect them.…”

Density‐ and size‐dependent mortality in fish early life stages

“…Capelin are pelagic as larvae, juveniles as well as adults (Gjøsæter, ). The transition from pelagic to demersal habitat is associated with habitat‐linked shifts in density‐dependent mortality, diet and predators (Juanes, ). As a hypothesis for further research, we propose that our findings may reflect a general pattern, namely that large body size at a transition from pelagic to demersal habitats may often give increased survival due to either size‐dependent predation by demersal fish or increased energy reserves.…”

Sole larval supply to coastal nurseries: Interannual variability and connectivity at interregional and interpopulation scales

“…A majority of marine fish species produce a high number of eggs with a low and variable probability of survival, i.e., survival rates close to 1/1000 from spawning to the end of larval stages (Juanes, 2007;Le Pape and Bonhommeau, 2015). The high sensitivity of larval survival to hydrodynamics and environmental conditions causes large variations in recruitment (Daewel et al, 2011) and largely explain the lack of significant stock-recruitment relationships for marine exploited fish (Vert-Pre et al, 2013;Cury et al, 2014;Szuwalski et al, 2015).…”