Increase in milt production by hormonal treatment in the pejerrey fish Odontesthes bonariensis (Valenciennes 1835)

Abstract

In spite of interest in the cultivation of the pejerrey ¢sh Odontesthes bonariensis (Cuvier & Valenciennes 1835), there are few studies on subjects required to advance this activity. One of the problems is the synchronization of female and male maturation to provide eggs and sperm for larval production. The low volume of expressible milt, either in wild or culture ¢sh, is a major problem. The aim of this work was to study the eiectiveness of the administration of diierent hormones on sperm production in pejerrey. Milt production was enhanced by the injection of human chorionic gonadotropin (hCG) (16.7-fold increase, 625 IU kg 1 ), carp pituitary extracts (13.5-fold increase, 30 mg kg 1 ), salmon pituitary extracts (12.8fold increase, 30 mg kg 1 ), salmon-type gonadotropin-releasing hormone analogue (GnRH) (16.7-fold increase, 10m gk g 1 ) and mammalian-type GnRH analogue (10.8-fold increase, 20m gk g 1 ). Sperm concentration, motility and the fertilization rate were not statistically diierent compared with control groups. It was also demonstrated that sperm could be obtained oi-season. Taken together, hCG is recommended to stimulate pejerrey spermiation because it is eiective in low doses is inexpensive and is widely available.