INDUCED SPAWNING OF THE BRAZILIAN FLOUNDER (PARALICHTHYS ORBIGNYANUS VALENCIENNES, 1839)

Abstract

Paralichthys orbignyanus is one of the most valuable flatfish in the southern coast of Brazil, due to its large size and high quality of flesh. So far, biological studies about this species are very rare, and it is not employed for cultivation. This study, undertaken from August 23, 1993 to September 29, 1993, presents the first induced spawning to obtain eggs and larvae of that species in laboratory. Mature adults were caught near Lagoa da Conceição (Florianópolis - SC). Females weighed 1,780 to 3,100 g, and males, 980 to 1,360 g. A total of four couples were injected with Human Chorionic Gonadotropin (HCG): 500 to 1,150 IU/kg for females, and 300 to 400 IU/kg for males. One female did not respond to the treatment and the other ones spawned after a latency period of 46 to 69 hours. Eggs were obtained through artificial fertilization from two females. The total productions of ovulated eggs were 224,000 and 280,000/kg of female, and the larval productions, was 40,500 and 83,200/kg of female, respectively. The best fertilization and hatching rates were 90%. The incubation time varied from 42 to 53 hours. The mean diameter of egg had 790 um, and the unique oil droplet, 116 µm. The mean Total length of hatched larva was 2.0 mm. Experiments of larviculture were not successful, larvae were unable to feed and starved after nine days. The tested hormonal treatment was effective for the spawning induction of the Brazilian flounder P. orbignyanus, and large amounts of eggs and larvae were produced.