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Preliminary results on artificial spawning and early stages characteristics of golden grouper, Epinephelus costae

Groupers of genus Epinephelus are among most interesting new fish species in Mediterranean aquaculture. Two species, white grouper Epinephelus aeneus and dusky grouper, Epinephelus marginatus were researched in few countries. The main problems are inconsistent results of hormonal treatments and almost total mortality during larviculture (Glamuzina et al., 1999). The golden grouper, Epinephelus costae is also selected as promisable species, due to good market value and expected high growth rate. However, there are only few published papers about biology and ecology in natural waters, and no data about artificial rearing or spawning. In this presentation, we will present results of the first attempt on artificial spawning, description of egg and larvae and results of larviculture. The same procedure of broodstock conditioning, hormonal treatments and rearing of larvae as previously reported for the dusky grouper, Epinephelus marginatus (Glamuzina et al., 1998) were applied. The only difference being higher temperature of 25-25.5 C of seawater. The hormonal treatments with HCG started on 20.08.1999. on one female (w= 4150 g) with average oocyte diameter of 550m, and with two sex-reversed males (W= 150; 250 g). Twelve hours after second hormone injections we started striping and fertilisation. Eggs and larvae were incubated in 350-l flow through plastic tanks, supplied with ambient seawater. Larvae were fed with small rotifers. Approximately 800 grams of relatively good eggs were obtained in first stripping and 500 grams of overripe and rotten eggs 24-h later. This female died 48 hours after second stripping. This indicates the need of more frequent stripping. The sex-reversed males gave sperm with 95% motility. The fertilisation of first batch of eggs was around 50%. The average diameter of fertilised egg was 938 m. The first cleavage started 60 min later. Hatching began after 24,15 hours and lasted two hours. The average length of newly hatched larvae was 1.76 mm, with a range of 1.69- 1.85 mm. Mouth opened 80 hours after hatching. Larvae started to feed with rotifers, but because of unexplained reason all died 10 days after hatching. We observe great similarity of spawning and egg and larval characteristics of golden grouper with previously described dusky grouper (Glamuzina et al., 1998).

goldblotch grouper; artificial spawning; egg; larvae

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