Overwintering Survival and Relative Mortality of Young of the Year Black Sea Bass Along the Northeast US Continental Shelf

Black sea bass Centropristis striata range from the Gulf of Maine to Florida, with two stocks separated by Cape Hatteras. In the northern stock, seasonal temperature variability elicits a seasonal offshore and southward migration not observed in the southern stock. The ability of Young-of-the-Year (YOY) black sea bass to survive winter depends upon the timing and extent of their seasonal migration offshore and their ability to survive cool water temperatures. Increased winter survival of YOY has the potential to allow this species to establish populations in waters where they have previously existed at low abundances. To quantify overwintering mortality in relation to temperature, salinity and size a series of experiments were conducted at 3°C and 5°C and salinities of 15 and 35 (n=144). An accelerated failure model was developed to characterize the pattern of mortality. The model will be applied to hindcasts of bottom temperature and salinity from Regional Ocean Modeling System (ROMS) to estimate winter mortality along the US NE continental shelf. To gauge what type of winter conditions result in fluctuations of recruitment rates each year we will compare recruitment of year one cohorts to estimates of overwintering mortality for each year in our study.