Plagioscion squamosissimus (silver croaker), a non-native species from the Amazon Basin, is one of the main resources supporting artisanal fisheries in the Três Irmãos Reservoir, São Paulo state, Brazil. This study evaluated its fishery biology and population characteristics between 2015 and 2018, aiming to provide information to support species management. Data were obtained through fishery monitoring of 93 artisanal fishers and quarterly scientific sampling conducted in the lotic, transitional, and lentic zones of the reservoir. Catch composition, fishing effort, environmental variables, length-weight relationship, length at first maturity (L50), and gillnet selectivity were analyzed. Spatial and temporal variability in catch per unit effort (CPUE) was assessed using principal component analysis and repeated-measures analysis of variance. The average annual landing of silver croaker was 53.5 tons, with a mean CPUE of 11.7 kg fisher-1 day-1. CPUE was associated with temperature, with the highest yields occurring in March, indicating a preference for lentic habitats. The species exhibited isometric growth (b = 3), continuous reproduction with a peak in spring, and a L50 of 15.9 cm total length. The results highlight the importance of silver croaker to local fisheries and suggest gillnet mesh sizes ≥ 8 cm to enhance commercial yields, whereas smaller meshes may be used in population control strategies.
The yellowtail lambari, Astyanax lacustris, is a small-sized species suitable for small-scale aquaculture. Five stocking densities (10, 25, 50, 75, and 100 fish/m2) were evaluated in three production cycles. Experimental units were 50-m2 earthen ponds, with minimal water replacement to compensate for infiltration and evaporation. Sixty-day-old fish (5.67 ± 0.10 cm and 2.67 ± 0.16 g) were fed a commercial diet twice daily in 45-day production cycles. Stocking densities influenced lambari growth. Lambari growth at all treatments showed good fit in the logistic model, but lower densities resulted in higher growth rates and larger asymptotic sizes. Among productive performance parameters, daily weight gain and specific growth rate were inversely proportional to stocking density, whereas the number of fish and biomass produced per area were directly proportional. These growth results were associated with reduced water quality and feed intake at higher stocking densities. Fish density did not affect feed conversion ratios (ranging from 1.44 to 1.58) but did influence carcass yield (82.00 to 84.85%). Under the conditions of this study, intermediate stocking densities showed good balance between growth and productivity per area.
This study evaluated morphometric traits as indirect selection criteria for high-yield phenotypes in dusky grouper (Epinephelus marginatus) reared under three commercial production systems: recirculating aquaculture systems (RAS), marine cages (MC), and estuarine ponds (EP). Fish (n = 55) were harvested at 730 days to assess carcass weight (CW) and meat volume (MV). Differences among systems were analyzed using analysis of variance followed by Tukey’s test (p < 0.05). Paired morphometric traits standard length (SL), head length (HL), body height (BH), and body width (BW) were evaluated through quadrant classification, and CW and MV were compared between quadrants using Welch’s t-test. SL × BH was the best-performing criterion in RAS and BH × BW in EP for CW, while no significant differences in CW were observed in MC. Overall, no significant differences in MV were detected among quadrants in any of the farming systems. Despite the limited sample size, these findings suggest that non-lethal morphometric traits may be useful for phenotypic indirect selection for a higher meat yield in dusky grouper aquaculture, depending on the production system.
Sepetiba Bay is an ecologically and economically significant lagoon for Rio de Janeiro, Brazil. However, the development of this region has been linked to numerous environmental contaminations, leading to the accumulation of trace metals across various ecosystems. Mercury is particularly concerned for public health due to its propensity to bioaccumulate and biomagnify in marine organisms, subsequently entering the human body through consuming contaminated fish. Six studies were identified, with their findings indicating that mercury concentrations in fish from Sepetiba Bay do not exceed the maximum limits set by national legislation (Brazilian Health Regulatory Agency) and the World Health Organization. This systematic review sought to compile research related to mercury contamination in fish from Sepetiba Bay between 2000 and 2024, following the PRISMA-P protocol. A total of six studies were selected, with an additional 27 articles included because of their relevance in understanding the feeding habits of fish, bringing the total to 33 articles. Our findings suggest that, despite the low risk to human consumption, there is a need for the development of public policies focused on the continuous monitoring and control of mercury contamination in the bay’s fish, intending to decontaminate the environment and prevent a progressive increase in mercury levels in species that constitute a significant part of the local diet.
Ultrasonography is a fast and non-invasive method that offers a promising alternative for sex identification and gonadal maturation assessment in fish. This technique is especially relevant to Brazilian sardine (Sardinella brasiliensis), a species of high commercial value whose small body makes traditional sexing methods unfeasible. Ultrasonography was applied to 55 individuals undergoing their first gonadal maturation. All fish were anesthetized for examination and subsequently euthanized for macroscopic evaluation to confirm sex and determine the maturation phase. These findings were supported by histological analysis, which confirmed the accuracy of the results. Ultrasonography using a multifrequency transducer (8–13 MHz) achieved 98% accuracy in sex identification, and 46 males and nine females were identified. Histological examination revealed 32 reproductively capable males (phase C) and 14 immature individuals (phase A), while all females were classified as phase C (ready for reproduction and spawning). Although ultrasonography proved effective for sex differentiation, it showed limitations in determining gonadal maturation phases. Further studies and the development of a specific protocol are required for accurate phase classification. Therefore, ultrasonography demonstrates great potential as a practical and effective tool in reproductive monitoring. This study is the first report of its application to the Brazilian sardine.
