ABSTRACT
Hoplias intermedius, of the Characiformes order and Erytrinidae family, is widely distributed across South America. This commercially interesting species can reach a length of 100 cm and a weight of 15-20 kg. To evaluate the reproductive biology of H. intermedius in the São Francisco River, Brazil, 154 males and 190 females were captured bi-monthly between September 2018 and August 2019 from the downstream regions of the Três Marias dam. Gillnets with differently sized meshes were deployed at distances of 34-54 km after the confluence with the Abaeté River (18°00'49â³ S, 45°10'51â³ W). Biometric data, gonadosomatic index (GSI), Fulton condition factor (K) and absolute fecundity (AF) were determined for each specimen. Gonad maturation stages and the spawning season were also established. The biometric data, GSI and K average values were relatively higher in females than in males. The reproductive peak for both sexes was reached around January/February. The mean AF was 4300.5 ± 1451.2 follicles per female. Fully developed vitellogenic follicles had a mean diameter of 1014.8 ± 250.7 µm, which is characteristic of fish with moderate fecundity. Fish of all maturation stages, from mature, spawned and spermed, occurred in all bimesters, indicating that this species reproduced throughout the year. The high frequency of spawning females throughout the year and the histological characteristics of spawned ovaries indicated that trairão H. intermedius' spawning type is partial.
Subject(s)
Characiformes , Reproduction , Male , Female , Animals , Fertility , Ovary , Brazil , SeasonsABSTRACT
Pampus argenteus is a species of economic importance for professional fishing and aquaculture. To analyse the quality of oocytes of P. argenteus, 10 females were kept in tanks of 200 m2 with an average depth of 1 m in the Integrated Center of Fishing Resources and Aquaculture of Três Marias - CODEVASF. Specimens were submitted to hypophysation-induced reproduction with crude extract of common carp pituitary (EBHC). Females received two doses (0.8-1.0 and 5.0-6.6 mg of EBHC/kg body weight, respectively), with a 12-h interval between doses. For males, a single dose (2.7 mg/kg body weight) was applied at the same time as the females' second dose. Oocytes were extruded manually 8 h after the second hormonal dose at 26°C. It was observed that seven females responded positively to the procedure while the other three released bloody and lumpy oocytes. For histological analysis, ovarian fragments were fixed in Bouin's liquid for 8-12 h and submitted to routine histological techniques. The protocol was considered successful for 70% of females and 100% of males. The fertilization rate of the females from the unsuccessful group was very low, and histological analyses showed that most of their oocytes were in follicular atresia, suggesting a delay in hormonal administration or extrusion could have occurred. Despite the hypophysation protocol being considered adequate for the induced reproduction of P. argenteus, complementary studies are necessary to evaluate the possible causes of this degenerative process.
