INDUCED SPAWNING OF THE MULLET Mugil platanus Gí­Å“NTHER, 1880, IN CANANÉIA, SÃO PAULO, BRAZIL

Reprodução induzida da tainha Mugil platanus Gunther, 1880, em Cananéia, São Paulo, Brasil

Abstract

Studies concerning the induced spawning of the mullet MugiL platanus were undertaken in June-September, 1989 and July-October, 1990 at the "Laboratório de Maricultura" in Cananéia, SP, Brazil. Females were chosen observing initial oocyte diameter, graphs of oocyte diameter frequency distribution, location of germinal vesicle, and number of oil droplets present in the oocyte. A total of 49 females were injected; 34 females received two doses of HCG: 20 and 40 IU per gram of total weight applied at 24-h intervals; 8 females received 10 mg/kg of mullet pituitary extract (MPE), and 30 IU/g of HCG; and 7 females received 20 mg/kg of MPE and 30 IU/g of HCG. The initial mean oocyte diameter of the selected females was between 532 µm and 621 µm and the percent frequency distribution of oocyte diameter was unimodal with the mode in 586 µm. High rates of fertilization and hatching were obtained with the either one of the above three treatments.