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 Ría 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 ~13°C, 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.

Maternal influence on the variation of the reproductive cycle of Trisopterus luscus (Gadidae)

“…In agreement with the previously described reproductive activity, the highest densities of pouting eggs were found in Galician waters during ichthyoplankton surveys conducted in winter and spring (Ferreiro and Labarta 1988). The short period of embryonic development described for T. luscus, 4.54 + 0.17 days at 13 ºC (Alonso-Fernández et al 2010), seems to indicate that larvae occur in the environment during the same peaks of reproductive activity. The latitudinal gradient is also reflected in the abundance of pouting larvae, which in the Irish Sea appear in April (Nichols et al 1993, Fox et al 1997, showing a delay in the spawning season relative to the coast of Galicia.…”

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“…Proportion of females of forkbeard in the Adriatic Sea was higher than males (1:0.62). It is different than sex ratio of Trisopterus minutus in the central Aegean Sea, where males were more numerous than females (1.29:1) (Metin et al, 2008). Sex ratio varies, not only between different species but also between populations of the same species from year to year (Metin et al, 2008).…”

“…Values of GSI obtained in this study are similar with those obtained for Trisopterus minutus in eastern Adriatic Sea which started to increase in December, peaked in February and then slowly decreased to minimum in September (Šantić et al, 2010). Metin et al (2008) observed that reproduction of Trisopterus minutus reached its maximum in January and continued until April, but in both sexes gonads started to mature in October same like in forkbeard. In Trisopterus luscus from Galician shelf, north-western Spain, GSI values rapidly increased between December and January with peak between January and March (Alonso-Fernández et al, 2008).…”

The real Nemo movie: Description of embryonic development inAmphiprion ocellarisfrom first division to hatching

“… 11 , 14 , 32 , 36 These well‐defined stages provide a framework for testing hypotheses of homologies within the various processes that occur during the embryonic development of teleost fishes. We observed interesting morphological differences between the embryos of false clownfish and other teleost species, whether they are aquaculture species (the sea bass Dicentrarchus labrax , 34 the turbot Scophtalmus maximus , 37 the batfish Platax teira 38 ), other coral reef fish (the damselfish Neopomacentrus cyanomus , 19 the dottybacks Pseudochromis dilecticus , 17 the mandarinfish Synchiropus splendidus , 39 the goby Elacatinus puncticulatus , 40 several angelfishes of the genus Centropyge 18 , 41 ) or other fish models (the stickleback G aculeatus , the salmonid Coregonus clupeaformis , 12 the gadid Trisopterus luscus , 42 the wrasse Labrus bergylta 43 ). These include the shape of the yolk/chorion, different early chromatophore patterns, and variation in developmental timing.…”