Gametogenesis in north west Atlantic teleosts

Abstract

Gametogenesis has been studied in oviparous teleosts including winter flounder (Pletironectes americanus), American plaice (Hip‐poglossoides platessoides), ’turbot’ (Reinbardtius bippoglossoides), capelin (Mallotus villosus), Atlantic salmon (Salmo salar), char (Salvelinus alpinus), and Atlantic cod (Gadus morbua). In the cold environment of the north west Atlantic prolonged gametogenesis may occur with variations in the rates of change and lengths of maintenance for different phases of the cycles. Staggered promotion can occur so that some fish have periods of short or prolonged asynchrony even when they eventually fit classical descriptions of synchronous gametogenesis. For winter flounder oo‐genesis fits expectations of a minimum three years overall with promotion into vitellogenesis 10–11 months before spawning, but for other species a shorter vitellogenic phase may occur. Fall‐spawning salmonids may initiate gametogenesis much earlier than some reports previously suggested, and are asynchronous until close to spawning. Female winter flounder, salmonids and capelin spawn in a short burst whereas American plaice and Atlantic cod are batch spawners, as is Reinhardtius (contrary to a previous report). All the species studied have iteroparous females but capelin males are essentially semelparous; however iteroparous species have individuals which may not spawn every year.