Induced Final Maturation and Spawning of the Marbled Grouper Epinephelus microdon Captured from Spawning Aggregations in the Republic of Palau, Micronesia

A high percentage (98.3%, N= 60) of the marbled grouper Epinephelus microdon individuals captured from spawning aggregations during July and August 1993 in the waters surrounding the island of Koror, Republic of Palau, Micronesia, were in the stage of maturity at which final maturation and spawning could be hormonally induced. The sex ratio of the captured fish was highly skewed towards males (4 male:1 female). Sexually immature females comprised the smallest size class, ( 0.6 kg BW, and individuals >1.5 kg BW (46.4 cm TL) were exclusively male. All females with oocytes that averaged (N= 50) >400 μm in diameter were successfully induced to spawn by a two-injection protocol using human chorionic gonadotropin (HCG) at total dosages of 2,100–3,200 IU/kg fish. All males used in the spawning trials were administered a single injection of HCG at dosages of 500 or 1,000 IU/kg fish. Fecundity ranged between 7.96 × 105−1.24 × 106kg BW, average spawned egg diameters ranged between 769–832 μm, percent fertilization ranged between 32.6%–99.9%, and hatching percentages were >90.0%. Total fat content of eggs obtained from a pooled spawning event was 14.1 mg/100 mg dry weight. The data indicate that HCG is a suitable treatment for the induction of spawning in marbled grouper females that possess a mean oocyte diameter of 400 μm or greater.

[1]  C. Tamaru,et al.  Status of the culture of milkfish (chanos chanos), striped mullet (mugil cephalus), and grouper (epinephelus sp.) , 1995 .

[2]  C. Tamaru,et al.  Chemical and physical differences in milkfish (Chanos chanos) eggs from natural and hormonally induced spawns , 1994 .

[3]  J. W. Tucker.  Spawning by Captive Serranid Fishes: A Review , 1994 .

[4]  E. Morriconi,et al.  Spawning aggregations of Merluccius hubbsi, in Patagonian waters: evidence for a single stock? , 1993 .

[5]  C. Tamaru,et al.  Fatty acid and amino acid profiles of spawned eggs of striped mullet, Mugil cephalus L. , 1992 .

[6]  K. Aida,et al.  Steroid profiles during maturation and induced spawning of the striped mullet, Mugil cephalus L. , 1991 .

[7]  K. Aida,et al.  Characterizing the stage of maturity most receptive to an acute LHRH-analogue therapy for inducing milkfish (Chanos chanos) to spawn , 1988 .

[8]  C. D. Kelley,et al.  The cost and effectiveness of CPH, HCG and LHRH-a on the induced spawning of grey mullet, Mugil cephalus , 1988 .

[9]  Shen Lin,et al.  Successful Use of Soybean Meal with a Methionine Supplement to Replace Fish Meal in Diets Fed to Milkfish Chanos chanos Forskal , 1988 .

[10]  S. Falk‐Petersen,et al.  Lipid class and fatty acid composition of eggs from the Atlantic halibut (Hippoglossus hippoglossus) , 1986 .

[11]  Takeshi Watanabe,et al.  Nutritional values of live organisms used in Japan for mass propagation of fish: A review , 1983 .

[12]  Takeshi Watanabe.  Lipid nutrition in fish , 1982 .