<em>Abstract.</em> —To satisfy the essential fish habitat (EFH) mandate of the reauthorized Magnuson-Stevens Fishery Conservation and Management Act, the Mid-Atlantic Fishery Management Council (MAFMC) and the National Marine Fisheries Service (NMFS) are developing objective, generic criteria to describe and identify the essential habitats for their managed species. Summer flounder or fluke <em>Paralichthys dentatus </em> is an important commercial and recreational species that occurs from shallow estuaries to the outer continental shelf from Nova Scotia to Florida. It is most abundant within the Middle Atlantic Bight from New England to Cape Hatteras, and this region is the focus of this paper. Summer flounder make seasonal inshore–offshore migrations; adults and juveniles normally inhabit shallow coastal and estuarine waters during the warmer months of the year and mostly move offshore with declining water temperature and day length during autumn. Adults spawn during the fall and winter migrations. The best habitat information available on summer flounder is for the estuarinedependent transforming larvae and juveniles. They use several different estuarine habitats as nursery areas, including salt-marsh creeks, sea grass beds, mudflats, and open bay areas. In these habitats, water temperature affects the seasonal occurrence of summer flounder, drives the inshore–offshore migration, and, particularly during winter and spring, affects first-year growth and survival and thus subsequent year-class strength. The distribution of transforming larvae and juveniles within the estuaries is significantly influenced by salinity gradients and substrate. Transforming larvae and juveniles show a preference for sandy substrates in the laboratory but also have been captured on mud or mixed substrates. Juveniles are attracted to eelgrass and macroalgae habitats because of the presence of prey but remain in nearby sand to avoid predators as well as conceal themselves from the prey. The MAFMC used the life history and habitat parameter information developed by the NMFS Northeast Fisheries Science Center (NEFSC) to precisely describe the EFH of summer flounder by life stage. Because summer flounder are overexploited, the MAFMC wanted to be conservative in its EFH identification. Therefore, 90% of the areas where each life history stage has been collected from offshore surveys were identified as EFH. The MAFMC proposed that 100% of the estuaries where larvae and juveniles were identified as being present be identified as EFH because these life stages are estuarine dependent. Nursery habitats within the estuaries are essential because they provide the best conditions for growth and survival of the transforming larvae and juveniles. Submerged aquatic vegetation beds are especially vulnerable and were identified as habitat areas of particular concern. As more habitatrelated density data become available from various local, state, and federal fishery-independent surveys, updated maps of distribution and abundance will be produced.
The potential effects of pre-settlement processes on post-settlement growth and survival of juvenile northern rock sole (Lepidopsetta polyxystra) in Gulf of Alaska nursery habitats
