Boletim do Instituto de Pesca

Larviculture of Nile tilapia (Oreochromis niloticus) in biofloc and clear water systems: masculinization with 17 α-methyltestosterone

Tue, 21 May 2024 00:00:00 -0300

We evaluated the use of the hormone 17α-methyltestosterone during the larviculture of Nile tilapia in biofloc and clear water systems. A completely randomized experimental design was adopted with four treatments and four replications: biofloc system without dietary hormone incorporation (BFT-D); biofloc system with dietary hormone incorporation (BFT-H); clear water without hormone incorporation in the diet (CLW-D); and clear water with hormone incorporation in the diet (CLW-H). The 28-day larviculture of Nile tilapia was carried out using 16 tanks with capacity of 15 L. The evaluations included water parameters, growth, survival, and gonad histology. The biofloc system displayed higher values for alkalinity, total suspended solids, settling solids, and turbidity compared to the clear water system (p < 0.05). Nevertheless, no difference (p > 0.05) was observed for in final weight, weight gain, feed conversion factor, survival, and growth rate between treatments. Then, tilapia post-larvae can be successfully reared in both biofloc and clear water systems without any negative impact on their zootechnical performance. Nonetheless, such results showed that tilapia can be reared in alternative systems, which can increase the production of this species.

Ecomorphology of yellowtail lambari (Characiformes: Characidae) in the neotropical semi-arid region, Brazil

Fri, 10 May 2024 00:00:00 -0300

The ecomorphological patterns of the Astyanax lacustris in different environments (lotic and lentic) of the semiarid region of Pernambuco were analyzed using 25 linear morphometric measurements on 240 specimens (120 males and 120 females), with standard lengths ranging from 24.25 to 91.50 mm. These data were converted into 16 ecomorphological attributes and correlated with environmental characteristics. The principal component analysis (PCA) explained 81.64% (first and second components) of the data variation, highlighting sexual dimorphism in specimen size and noticeable variation among individuals of the same sex in different environments. Specimens from lotic environments showed higher caudal peduncle compression index (CPCI) values, while the pectoral fin aspect ration (PFAR) was more pronounced in lentic environments. Overall, females exhibited a wide morphometric variation. Analysis of linear morphometry in different water bodies indicated an intrinsic variation related to hydrodynamics linked to sexual dimorphism and water flow speed. Further studies are suggested to investigate whether factors such as macrophytes and different levels of water depth and flow contribute to this morphometric variation of species in the semi-arid region.

Assessment of fish farming environmental suitability scenarios in compliance with the Brazilian Forest Code

Mon, 24 Jun 2024 00:00:00 -0300

This study aimed to evaluate environmental suitability scenarios for fish farms in Santa Catarina, Brazil, applying the rules regarding suitability and occupation in Permanent Preservation Areas (PPAs) of the current Forest Code. Rural properties (n=15) with commercial aquaculture were selected to verify the occupation scenarios in PPAs. The suitability analysis was based on the legal regulations that guide the activity’s licensing process, later with the inclusion of public databases that make up this environmental policy. From the suitability maps per property in different scenarios, in the most restrictive rule, 93.3% of the properties analyzed presented environmental liabilities due to occupation in PPAs. Based on the least restrictive rule, 80% of the rural properties presented environmental liabilities. Considering the ideal scenario, in which PPA occupation is absent, 6% of the fish farms were identified; in the less restrictive scenario, 16%; and in the restrictive scenario, 78% of the fish farms. In conclusion, legal uncertainty surrounding the application of the NFC in the Atlantic Forest biome can be an obstacle to the regularization of environmental processes in fish farming. However, is possible and feasible in both scenarios, only for occupation profiles III and IV is it more particular to continue with the activity, considering the minimum recomposition rule.

Diversity and similarity in parasitic infracommunities of Mylossoma aureum and Mylossoma duriventre (Characiformes, Serrasalmidae) from the Middle Madeira River Basin, Southern Amazonas, Brazil

Wed, 20 Mar 2024 00:00:00 -0300

A total of 30 specimens of Mylossoma aureum and 30 of Mylossoma duriventre from the Middle Madeira River Basin were examined between October 2020 to March 2021. Eight species of parasites were identified. About 65% of the hosts were parasitized. A total of 386 parasites was collected in M. aureum and 436 in M. duriventre. Species accumulation curves in M. aureum did not reach the asymptote, while in M. duriventre the curves showed tendency to stabilization. Contracaecum sp. larvae was the only endoparasite found. Anacanthorus paraspathulatus was the dominant species in M. aureum. In M. duriventre, the core species with highest parasite indexes was Mymarothecium sp. 3. Margalef’s and Shannon’s diversity indexes were higher in M. aureum. Most of the parasites showed an aggregated distribution pattern. Mymarothecium sp. 1, Mymarothecium sp. 2 and the parasite richness showed a significant positive correlation between its abundance and host length and between Mymarothecium sp. 1 abundance and host weight in M. aureum. All parasites are the first records for the Southern Amazonas. Except A. paraspathulatus, all M. aureum parasites are mentioned for the first time in this host. The three morphotypes of Mymarothecium spp. are probably new species that are in the process of taxonomic description.

Evaluation of feeding table optimizations in Pacific white shrimp nursery biofloc systems

Fri, 24 May 2024 00:00:00 -0300

A 45-day experiment was conducted to optimize feeding rates in the nursery phase of Pacific white shrimp reared in biofloc systems (BFT). Four treatments were evaluated in quadruplicate, according to the Van Wyk table: maximum feeding rate; minimum feeding rate; minimum feeding rate minus 10%; and maximum feeding rate plus 10%. Post-larvae (0.08 ± 0.00 g) were cultured at the density of 2,000 shrimp·m^-3, and water quality, solids production, and productive performance were all monitored. No significant difference was observed in final mean weight (1.47 ± 0.17 g), productivity (2.34 ± 0.20 kg·m^-3) and survival (85.29 ± 5.44%) among treatments, but feed conversion ratio was significantly lower in the minimum feeding rate and minimum feeding rate minus 10% treatments, indicating efficient feed conversion without compromising growth. These treatments also resulted in lower values of toxic nitrogen compounds and total suspended solids, suggesting a positive impact on water quality. Although these rates proved suitable, continuous adjustments are needed owing to variations in the BFT system. This study provides guidelines for optimizing feeding management in superintensive BFT nursery systems.

Confirmed by integrative taxonomy first and unusual occurrence of the exotic shrimp Neocaridina davidi (Caridea: Atyidae) in Brazil

Tue, 21 May 2024 00:00:00 -0300

A shrimp specimen of the genus Neocaridina Kubo 1938, originally from Asia, was collected for the first time in a natural marine environment in Pernambuco, Brazil. This represents the first record of this genus in the South American continent. Morphological characteristics and mitochondrial and nuclear DNA sequences (COI, 16S, 18S, and H3) of the specimen were compared with other species of Neocaridina, enabling its identification as Neocaridina davidi. Finding this freshwater species native to mainland China in a marine environment was surprising. Based on prior findings in other locations, the most likely hypothesis for this unusual occurrence is that the shrimp may have been released intentionally or unintentionally into the environment by an aquarium hobbyist.

Importance of fishing permits in no-take marine protected area overlapping with fishing grounds

Mayra Jankowsky, Diego Albino Morroni, Jocemar Tomasino Mendonça — Fri, 28 Jun 2024 00:00:00 -0300

Public policies in marine areas are often constructed while ignoring the presence of artisanal fishing. Consequently, conflicts arise, and public policies become ineffective. Studies aimed at reducing such conflicts have been conducted worldwide. We analyzed an example, a no-take marine protected area (NTMPA) that overlaps with fishing grounds. This conflict was mitigated through an agreement that established: catch species, vessel numbers, and permitted periods. We evaluated the significance of NTMPA using fish landing data from fishery monitoring program. For this, we present the use of fishing grounds through heat maps, along with the importance of the permitted species regarding: production, via relative importance index; and profitability, through first-sale value relative to fishing days. Results showed that NTMPA has high productivity and profitability in relation to two of the three fishing resources allowed, which are among the most important local resources. Although the agreement established is valuable, it has limitations: transitory nature, and strict rules. Maintenance of this agreement and creation of permanent spaces for dialogue to adaptation on rules are recommended. Subsequently, recategorization of the NTMPA such that sustainable regulated use is allowed should be debated.

Prebiotic, probiotic and marine algae suplementation in juvenile tilapia diet

Wed, 24 Apr 2024 00:00:00 -0300

This study evaluated the probiotic mannan oligosaccharide (MOS), and marine algae for Nile tilapia (Oreochromis niloticus) feeding. The parameters analyzed were fish-growth rate, hematological and immunological parameters, and intestinal microbiota. Also, fish were submitted to experimental infection challenge with Aeromonas hydrophila to evaluate the immune response. Nile tilapia juveniles (weight 8.86 ± 3.22 g) were used in the six treatments with four replicates, for 63 days. The treatments were: control basal diet; PAS-TR: basal diet plus 0.04 g·kg^-1 of the probiotic (Bacillus cereus and Bacillus subtilis); MOS: basal diet plus 4 g·kg^-1 of the prebiotic mannooligosaccharide, 4 g·kg^-1of the prebiotic Kappaphycus alvarezii. Two more diets were formulated by a combination of PAS-TR + MOS (4 +4 g·kg^-1), and PAS-TR + KAP (4 +4 g·kg^-1). For the challenge experiment, the fish were fed for 21 days, infected via intraperitoneal injection with A. hydrophila (1 x 106 UFC·mL^-1), and the mortality rate was registered for 15 days post-infection. Results indicated the capacity of probiotic to remain in the gut for 63 days, and it was inhibited neither by autochthonous microbiota nor by prebiotics used. The feed additives tested for Nile tilapia did not cause a beneficial or adverse effect on growth or hematological variables. However, these treatments protected the fish from A. hydrophyla infection, proved by higher survival rate, and relative protection levels. We concluded that probiotic PAS-TR and prebiotics MOS and KAP, combined or not as symbiotics, may promote immune protection and reduce the mortality rate of A. hydrophyla infection.

Morphological analyses of otoliths indicate a single population of invasive Arapaima gigas in tributaries of the Upper Madeira River (Amazon Basin)

Fri, 28 Jun 2024 00:00:00 -0300

The present study aimed to evaluate the potential of the shape of the sagitta otolith to discriminate populations of Arapaima gigas outside their natural area of occurrence in different tributaries of the Madeira River. Otolith samples were collected at three locations along the Guaporé and Mamoré rivers. The shape of the otolith was described using 20 Fourier harmonics and five shape indices. No significant differences were found in the shape of the otoliths among the different sample areas, and no evidence of relevant differences between groups was observed graphically for the two methods used. The success of the global classification of the models was considered average, being 57.57% for the shape indices, and 55.54% for the Fourier coefficients. Thus, the results suggest a single population of pirarucu in different locations of the Guaporé and Mamoré rivers. However, multidisciplinary studies involving genetics, morphology, and ecology may provide more accurate guidance for determining pirarucu populations in the study region.

Application of biofloc technology in the larval rearing of zebrafish (Danio rerio)

Mon, 05 Feb 2024 00:00:00 -0300

The aim of this study was to investigate the different strategies of biofloc addition to zebrafish (Danio rerio) larviculture, and evaluate their growth and biochemical parameters. Three treatments were used: addition of 200 mL biofloc once at the start of the assay (O1), addition of 100 mL biofloc every seven days (1W), and addition of 100 mL biofloc every four days (2W). The 1W and 2W treatments also received 200 mL biofloc at the start of the assay. Regarding water quality, the only difference was the total suspended solid concentration, because the 2W treatment had a higher concentration in the final assay (127.6 ± 24.3 mg L^-1). The final weight, survival rate, and juvenile percentile did not show statistical differences among the treatments. However, the O1 treatment exhibited a higher total length (11.93 ± 0.45 mm) than those in the 2W treatment. The juveniles in the 2W treatment exhibited lower nonprotein thiols and higher TBARS concentrations than those in the other treatments. Thus, the biofloc system can be a viable alternative to zebrafish larviculture without the use of conventional live food, and the addition of biofloc once (O1) at the beginning of larval rearing achieves good growth and survival results.

Transport simulation of Brazilian sardine Sardinella brasiliensis (Steindachner, 1879)

Fri, 28 Jun 2024 00:00:00 -0300

The aim of this study was to investigate the ideal density to use in transport operations for Brazilian sardines Sardinella brasiliensis (Steindachner, 1879). For this purpose, 4,020 juveniles S. brasiliensis (0.51 ± 0.10 g and 3.89 ± 0.32 cm) were randomly distributed in 60L-polyethylene bags filled with 20 L of water (salinity 35 g/kg) at densities of 15, 10, 5, 2.5 and 1 g∙L^-1, all in triplicate. The transport bags were inflated with pure oxygen (about ⅔) and sealed with elastic bands. The duration of the simulated transport was 24 h. Then, survival rate, as well as analyses of water quality, was performed. The results showed that density had considerable influence on survival and water quality. At the density of 15 g∙L^-1 dissolved oxygen reached 0.0 mg∙L^-1, causing 100% mortality at the end of the experiment, while the density of 10 g∙L^-1showed a higher amount of N-NH₃in the water. Survival was the same at densities below 10 g∙L^-1. Densities ≤ 10 g∙L^-1are recommended for the transport of S. brasiliensis lasting up to 24 h.