Abstract
The goals of this study were to evaluate dourado female egg viability submitted to stress condition caused by two different reproductive induction methods, extruded and semi-natural. Sixteen females randomly chosen were induced with pituitary extract and allocated in two groups; the first, in which oocytes were manually extruded and the second group, females were allowed to naturally spaw. Blood samples were collected for glucose, cortisol and hematocrit determinations as well as for red blood cells and white blood cells smears evaluations. A control group had its blood collected before hormonal induction. Fertilization rate was 40.6 and 91.7% for extruded and semi-natural methods, respectively, and the survival rate was higher in semi-natural groups. Both experimental groups showed higher glucose and cortisol levels compared to control group. The results for hematocrit, hemoglobin concentration and erythrocytes numbers did not differ among groups. Extruded and semi-natural procedures elevated monocytes percentage. In conclusion, the semi-natural procedures are more efficient than extruded method and should be taken into account for Salminus brasiliensis handling of breeders. Key words: Fish breeders, reproductive methodology, hematological parameters.
Highlights
Dourado, Salminus brasiliensis (Cuvier, 1816), from Characidae family, is broadly distributed at Pantanal, Paraná, Uruguay, São Francisco watersheds as well as at Lagoa dos Patos associated-basin (Morais and Schubart, 1955; Gomes et al, 2003)
The experiment was conducted with 32 males and 16 females of dourado randomly chosen from the broodstock of Hydrology and Aquaculture Station of Duke Energy International, located at Salto Grande, Sao Paulo State, Brazil (49° 130 W and 23° 100 S)
According to Bromage et al (1994), eggs releasing at the time of spawning is crucial for egg quality; in such way, the release of eggs before or after this event can lead to low fertilization rates and low quality fish larvae (Springate and Bromage, 1985)
Summary
Salminus brasiliensis (Cuvier, 1816), from Characidae family, is broadly distributed at Pantanal, Paraná, Uruguay, São Francisco watersheds as well as at Lagoa dos Patos associated-basin (Morais and Schubart, 1955; Gomes et al, 2003). It is a carnivorous fish, found in lotic environmental and performing ascending reproductive migrations (Streit et al, 2007). Zaniboni and Schulz (2003) assigned the dwindling of this specie in nature to riparian deforestation, fishing and capture of young specimens, drainage of adjacent lagoons and alterations of hydrological regime caused by dams’ construction, water contamination and nonnative.
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