Embryonic development and spawning pattern of Trisopterus luscus (Teleostei: Gadidae) under controlled conditions

Abstract

Knowledge on early ontogeny of Trisopterus luscus is scarce and incomplete. This paper describes the first successful attempt ever at achieving the natural spawning in captivity for this species. The reproductive specimens used for this study were obtained in the Rı´a de Vigo in September 2008 and subsequently transported to the facilities of the Institute of Marine Research (CSIC). The spawning frequency was variable among females, 1.8–4.6 days, but no size-dependent trend was determined. The average batch size, i.e. the number of eggs released per batch, has proven significantly dependent on female length and weight. In the present study the complete embryonic development in controlled conditions (sand–filtered seawater at 138C, with natural photoperiod), from egg to hatched larva, has been described for the first time ever. The development of pouting eggs was divided into six stages, based on the artificially-reared material. Pouting eggs are pelagic with a smooth, clear and spherical chorion, and a homogeneous yolk. The perivitelline space is narrow and oil globules are absent. Live eggs fertilized were 0.95–1.10 mm in diameter. The embryo hatches as a yolk-sac larva with closed mouth and gut. The pouting eggs hatched during the latter half of the fifth day