Annual antifreeze cycles in Newfoundland, New Brunswick and Long Island winter flounder Pseudopleuronectes americanus

Abstract

Annual cycles of plasma antifreeze peptide levels were compared in winter flounder Pseudopleuronectes americanus from 3 areas: Conception Bay, Newfoundland; Passamaquoddy Bay, New Brunswick: and Shinnecock Bay, Long Island, New York. Winter flounder from the most southerly population, Shinnecock Bay, initiated antifreeze peptide production at the same time of year (Nov) as did flounder from the most northern population (Newfoundland). Flounder from a geographically intermediate population, Passamaquoddy Bay, produced antifreeze peptides approximately 2 mo later (Jan). The differences observed did not correlate with differences in seawater temperatures. Antifreeze peptides disappeared from the plasma during March in the Shinnecock Bay flounder, April in the New Brunswick flounder, and May in the Newfoundland flounder. These differences correlated with the regional differences in the time at which the water temperature increased. It is hypothesized that the time of antifreeze production is a genetically determined population characteristic which reflects the earliest date that antifreeze peptides would be essential to their surviva