Reproductive biology and fecundity of the Bay of Biscay anchovy population (Engraulis encrasicolus L.)

摘要: SUMMARY: This review presents the results of field studies conducted between 1987 and 1992 on reproductive biology fecundity Bay Biscay anchovy. Close to 100% anchovy population reach maturity during season, although smallest 1-year-old mature slightly later. At peak spawning, however, output (numbers eggs laid daily per unit body weight) one year old is similar that older Anchovy mainly spawn from 19:00 6:00 (GMT) with a at 00:00 (GMT). For females spawning given night, final maturation process batch oocytes starts night before. The nuclear migration proceeds through first part following day. Oocytes start hydrate early in afternoon day spawning. Hydration reaches its maximum intensity dusk night. Gonads postovulatory follicles can already be observed before dusk, indicating activities. spawner indeterminate fecundity. ‘De novo’ vitelogenesis immature season. Annual determined by both number (batch fecundity) spawnings season (frequency duration season). Batch an increasing pattern as advances, ca. 200 /g April, 500 650 eggs/g May June respectively. fraction ranges 18 33%, increases progresses. high frequency may related relatively short Assuming two month protracted total range ca 9,000 11,000 gonad-free weight (g).