Closing the cycle of commercially important fish in a recirculating aquaculture system (RAS) is growing in importance for stablishing culture protocols. From wild broodstock, it is possible to lab-produce juveniles. Subsequently, the juveniles are taken systems for grow-out and gonadal conditioning is implemented along with a controlled environmental, which facilitates the process of maturation, ovulation and voluntary spawning in captivity. In this investigation, a broodstock was established from juveniles produced in the laboratory (F1) of barred sand bass Paralabrax nebulifer with the use of RAS and voluntary spawning quality obtained under controlled conditions was evaluated.
The juveniles grow-out and gonadal conditioning is implemented with the photoperiod and temperature control (13:11 L:D; 22 ºC) in a RAS, which facilities the voluntary spawning in captivity. The broodstock group was composed of 6 females:4 males. To assess the quality of spawnings, the following parameters were determinated: volume of floating and non-floating embryos (Figure 1), embryo diameter, oil globule diameter, notochordal length (NL), yolk sac volume, hatching rate and survival percentage. The embryos/larvae were observed daily from day 0 to 3 days after hatching (DAH). The total number of spawns obtained each month was compared by means of a one-way analysis of variance. Statistical analysis was performed with the software Statistic 10.0.
The highest volumes of floating embryos were observed during April to June. In the embryos, the mean diameter was 0.88 ± 0.02 mm. The hatching percentage between the evaluation months did not show significant differences and had a mean value of 73.4 %, while the average survival percentage was 32.4 %. In the eleutheroembryos and apterolarvae, there were not significant differences in the mean NL at 1 and 3 DAH and it was 1.64 ± 0.24 mm and 2.16 ± 0.19 mm respectively.
Although larval survival is still a factor to consider, being able to conclude the life cycle and have reproductive availability in the captivity offers a significant step for to achieve the cultivation of this species.