Abundance and distribution of atlantic sturgeon (acipenser oxyrinchus) within the northwest atlantic ocean, determined from five fishery-independent surveys

Abstract-A lack of knowledge of how oceanic habitat is used by juvenile marine migrant Atlantic sturgeon (Acipenser oxyrinchus) is hindering conservation measures directed at restoring severely depleted populations. Identifying the spatial distribution of Atlantic sturgeon is necessary to identify critical habitat and appropriate management actions. We used five fishery-independent surveys to assess habitat use and movement of Atlantic sturgeon during their marine life stage. The size distribution ranged from 56 to 269 cm total length (mean=108 cm). Ninety-eight percent of all Atlantic sturgeon were smaller than 197 cm-a size that indicated the majority were immature. The pattern of habitat use revealed concentration areas and potential migration pathways used for northerly summer and southerly winter migrations. Atlantic sturgeon were largely confined to water depths less than 20 m and aggregations tended to occur at the mouths of large bays (Chesapeake and Delaware bays) or estuaries (Hudson and Kennebec rivers) during the fall and spring and to disperse throughout the Mid-Atlantic Bight during the winter. In most surveys depth, temperature, and salinity were significantly related to the distribution of Atlantic sturgeon. Knowledge of their habitat and movements can be used to devise spatially based conservation plans to minimize bycatch and to enhance population recovery.