Feeding, growth and survival of juvenile summer flounder Paralichthys dentatus: experimental analysis of the effects of temperature and salinity

Abstract

There was 100% survival >3°C, suggesting that juvenile summer flounder are able to survive most winter water temperatures encountered in north/central Mid-Atlantic Bight (MAB) estuaries. Mortality was 42% after 16d at 2-3°C, and was highest in fish <50mm Tl (1g). Mean specific growth rates were not significantly different between 2-10°C (mean 0.14%d-1); these rates were not significantly different from zero. Mean growth rate increased to 2.4%d-1 at 14°C and 3.8%d-1 at 18°C. Mean assimilation efficiency (60.1%) was not affected by temperature. Mean growth efficiency was significantly lower at 6°C(-23.1%) than at 14 and 18°C (18.4 and 22.1%, respectively), and was highly variable. Salinity had no significant effect on any parameters measured. Mortality resulting from acute exposure to low temperature probably occurs during one 2-4 wk period each winter. Recruitment success from north/central MAB estuaries may be lower in years with late winter cold period. Additional mortality probably results from low growth rates caused by sub-optimal temperatures (<10°C) throughout spring. -from Authors