Can adult Black Sea Bass overwinter in Long Island Sound, USA?

Objective We experimentally tested whether adult Black Sea Bass Centropristis striata belonging to the northern stock could theoretically overwinter in Long Island Sound (LIS) and whether doing so would affect their survival, growth, and gonadal investment and the lipid and lean content of their gonad, liver, and white muscle tissues. Methods Fish were caught via hook and line in LIS before and after their offshore winter migration (October 2022 and May 2023, respectively). Fifty individuals from October were reared for 200 d under flow-through conditions and fed diets of crushed mussels or herring. At the end of the experiment, laboratory and wild fish were assessed for their growth, gonadosomatic index, hepatosomatic index, and tissue-specific lipid and lean contents. Results Laboratory fish experienced unfavorable winter temperatures (∼5–12°C) for more than 5 months, exhibiting negligible growth and high mortalities. Mortalities began accruing after temperatures had reached their seasonal minimum of about 5°C in early February (day 120). Mortalities were lower for fish on the mussel diet (40%) than for those on the herring diet (68%), but survivors from the latter group had higher tissue lipid contents. Wild Black Sea Bass returning to LIS in spring had higher tissue lipid contents and greater gonadosomatic indices than surviving laboratory fish on either diet. Conclusions At present, overwintering in LIS appears possible but likely disadvantageous for Black Sea Bass because offshore winter migration results in greater energy reserves and subsequent reproductive investment. In the future, however, warming coastal waters will continue to shorten the duration of unsuitable winter temperatures, which could become conducive to year-round inshore residency or partial migration patterns in the northern stock of Black Sea Bass.