Saline acclimation of striped mojarra Eugerres plumieri (Cuvier 1830) and optimal dosage of carp pituitary extract (CPE) to induce spawning

Abstract

The main objective of the current study was to determine an optimal dosage of commercial carp pituitary extract (CPE) of the conventional heteroplastic hypophysation technique to induce spawning in the wild caught striped mojarra broodstock Eugerres plumieri under laboratory conditions. We also describe trials testing saline acclimation regimes (changes from 10 parts per thousand to 30 parts per thousand) prior to hormonal induction. For saline acclimation, three treatments were performed: first and second treatments began 1-day after conditioning of broodstock fish with a total duration of the saline changes lasting 1-day and 2-days, respectively. The third treatment began 30-days after conditioning with a 7-day saline regime. After reaching 30 parts per thousand, all fish from the first and second treatments died after the fourth and ninth days, respectively

while the fishes in the third treatment survived more than two years. These fish remain on public exhibit in the "Mundo Marino" Aquarium, Santa Marta, Colombia. Four treatments of hormonal induction were tested on females using a total concentration of 5-mg of CPE per kg of body weight: first, second and third treatments were applied in two hormonal doses that corresponded to 10%-90%, 30%-70% and 40%-60%, respectively, with time intervals between doses of 14-h for the first and second treatment and of 12-h for the third treatment. The fourth treatment was applied in four hormonal doses that it corresponded to 20%-20%-30%-30% with 12-h time intervals between doses. Only the fishes of the fourth treatment resisted the induction, continued to live and reached spawning artificially. Water temperature remained at 28 +/- 1 degrees C and at 30 parts per thousand salinity during the study. The "dry" method of fertilization was used. The fertilized eggs were incubated at 30 parts per thousand and 35 parts per thousand salinities. These eggs reached the Morula early stage, but were later attacked by protozoan. These results suggest that fast changes of saline and limited hormonal dosages do not offer effective results in Eugerres plumieri. This work provided fundamental procedures for the culture and maintenance of live broodstock for striped mojarra in saltwater and/ or coastal lagoon habitats and provides an effective and viable dosage of CPE for artificial spawning and commercial production in this species.