15 MARCH 1999
INDUCED SPAWNING AND LARVAL REARING OF DOMESTIC HYBRID STRIPED BASS (MORONE SAXATILIS X M-CHRYSOPS) IN TAIWAN
F.G. Liu, S.C. Cheng, H.C. Chen-1998
Israeli Journal of Aquaculture - Bamidgeh, 50(3): 111-127
Abstract:
This is the first study on the induced spawning and larval rearing of captive F-1 hybrid striped bass (Morone saxatilis x M. chrysops) in Taiwan. Imported fry of F-1 hybrid striped bass were held in an earthen pond and fed exclusively commercial floating pellets. They reached sexual maturity at two years old and were successfully induced to both strip spawning and tank spawning by a single hormone injection. Human chorionic gonadotropin (HCG), at a dosage of 300-400 IU/kg, was the most effective treatment. Low doses of HCG (200 IU/kg) or LHRH-a (luteinizing hormone releasing hormone analogue; 30 mu g/kg) alone were moderately effective, while groups injected with 10 mu g/kg LHRH-a, or saline and the untreated control did not spawn. In terms of the fertilization rate, hatch rate and level of larval deformities, no significant difference was found between tank spawning and strip spawning. Fertilization rates ranged from 76.3% to 96.7% and hatch rates were between 1.6% and 24.2%, whereas the level of larval deformities ranged between 19.2% and 100%. Hatched larvae were reared in 2 m(3) circular fiberglass tanks and fed initially on rotifers and Artemia nauplii, followed by daphnia, and finally converted to fish starter crumble. Two batches of larvae were reared and survived to the juvenile stage (7.3-7.9 cm TL) in 1996. Larvae developed to the juvenile stage 21-28 days after hatching and measured 12.10 to 18.24 mm TL. The juveniles reached a mean total length of 7.5 cm after 77 days of rearing with an average survival rate of 2.65%. The F-2 progeny exhibited a low hatch rate, low survival, high level of deformities and growth variability which suggests that F-2 progeny may not be suitable for culture.
(Natl Taiwan Univ, Inst Zool, Taipei 107, Taiwan)