THE INFLUENCE OF AGONISTIC BEHAVIOR ON REPRODUCTIVE PERFORMANCE IN CAPTIVITY REARED FEMALES IN AN ENDANGERED SILURIFORM SPECIES, Steindachneridion parahybae

LEONEL MORANDINI; MARTÍN ROBERTO RAMALLO; RENATO MASSAAKI HONJI; RENATA GUIMARÃES MOREIRA; DANIELO CANEPPELE

Cape Town

Congreso; World Aquaculture 2017; 2017

World Aquaculture Society

The Neotropical teleost Steindachneridion parahybae is a gonochoristic medium-sized siluriform species, an important migratory (reophilic fish), ichthyophagous and freshwater fish, endemic to the Paraíba do Sul River Basin (Brazil), seriously endangered in this basin and regionally extincted in São Paulo State. The scarce biological information of S. parahybae and the critically endangered situation highlight the importance of increasing the knowledge about the reproductive biology in this species under captivity aiming to conservation. In this framework, the aim of this study was to evaluate the influence of agonistic behaviour of S. parahybae on reproductive performance in captivity reared females. Broodstocks that were able to spawn were selected in the pounds at the Hydrobiology and Aquaculture Unit of CESP (Companhia Energética de São Paulo, Southeast, Brazil) during the reproductive period (February), and then immediately induced to reproduce by combining whole acetone-dried carp pituitary extract and human chorionic gonadotropin (conventional protocol). After hormone administration until spawning, two female's broodstocks were placed together into glass aquarium in the CESP laboratory to facilitate the observation of reproductive behavior during artificial induction. All broodstocks (n=10, 100% survival) induced to spawning responded positively to the artificial reproduction. Following the second hormonal dose, it was possible to observe a gradual increase in the animals' activity, including aggressive behavior that even hurt one of the females. One of the females chasing the other, trapping it in a corner of the aquarium, and sometimes, these chasing were with physical contact between females, showing some bites and tail hit behavior. Later, at the end of the period artificial spawning, at the time of manually stripping for gamete collection; some females were damaged and others did not have any injury. We defined as "dominant" female, the ones which showed more aggressive behavior and did not have any injury and "no-dominant" the females that were injured. These injuries were observed throughout the body of non-dominant female, including the dorsal part of the body and caudal fin (Fig.1). All major reproductive results are summarized in Table 1. Our results contribute to improve the protocol to obtain a better reproductive performance in captivity, since their endangered status deserves special attention and urgent action for contribution to the knowledge of reproductive physiology, which is the basic premise for the program of fish restocking in the Paraíba do Sul River Basin.