Boletim do Instituto de Pesca

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

2023-11-14T15:32:52-03:00

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.

Ichthyoplankton distribution in a fragmented river stretch in a semi-arid Brazilian watershed

2024-02-03T19:47:39-03:00

The Jequitinhonha River in Brazil is located in a region with a large proportion of endemic freshwater fish species. Currently, it is fragmented in its middle stretch by the Irapé Hydroelectric Power Plant. Few studies have been done on the dynamics of fish eggs and larvae in this region. Thus, the objectives of this study were to present a panoramic view of the spatial and temporal distribution of the eggs and larval assemblage in the Upper-Middle stretch of Jequitinhonha River Basin, and to relate them to the existing environmental characteristics. Sampling was conducted every three days between October 2014 and March 2015 at two stretches located upstream and two downstream of the dam. A total of 2,916 eggs and 2,709 larvae were collected. The highest density of eggs and larvae was collected in the environments located downstream of the dam, but the fragmentation of the Jequitinhonha River by the dam did not influence the distribution of larval assemblages either upstream or downstream of the reservoir. The environments downstream of the dam, especially the Araçuaí tributary, appeared to significantly contribute to the reproductive success of fish species in the region.

Oxygen consumption of the dog snapper in captivity: implications of water quality and fish stage

2024-01-17T12:59:16-03:00

Respirometry represents the least invasive method to investigate fish physiology. Therefore, oxygen consumption (OC) of the dog snapper Lutjanus jocu was evaluated in two specific culture water conditions: the cleanest possible water, and accumulated nitrate water. Clean water represents the seawater collected straight from the environment with a basic treatment, and nitrate water represents the seawater kept at the rearing tanks using advanced water treatment in its recirculating system, in which nitrogen compounds accumulate. Fish were classified into stages, and median OC for juvenile, grow-out and broodstock stages were 322.4, 176.5 and 78.4 mg·(kg·h)^-1, respectively. Despite no significant differences in OC for the dog snapper were found during day and nighttime, this last condition represents a 5% increase on the measurements, possibly related to the circadian rhythm of this species, known for being active during the night. Remarkable increase in respirometry is observed in the dog snapper grow-out stage cultured in nitrate water. This condition demands extra management of the production to promote fish welfare, and consequently better growth.

Otolith morphometry for the determination of the theoretical growth curve of fish

2024-06-28T16:15:24-03:00

During the period from November 2019 to August 2021, a total of 43 specimens of Leporinus friderici, 18 of Prochilodus lineatus, 17 of Hoplias intermedius and 8 of Cichla kelberi were caught in the Verde River basin (Mato Grosso do Sul, Brazil) using various types of fishing equipment. Data collection consisted of measuring fish lengths (L_Oa, mm) and area (O_a, mm²) of their respective sagitta otoliths. The modified Von Bertalanffy equation (1938) was used to determine the theoretical growth curve as a function of the otolith area. The results indicate that the length of the fish increases in relation to the increase in the otolith area, resulting in a strong logarithmic regression for all species studied. The values of the theoretical growth curve of the fish (observed and estimated) as a function of the areas of the otoliths showed adjustments of R²>75 for the measured and R²>90 for the estimated values. Therefore, the otolith area proved to be adequate for the estimation of growth for the species, which can also facilitate the evaluation of fish length, band is a useful tool for the evaluation of fish stocks.

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

2023-11-13T10:05:02-03:00

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.

Reproductive biology of the largehead hairtail Trichiurus lepturus (Teleostei: Trichiuridae): implications to the fisheries management on shallow coastal waters in northeastern Brazil

2024-08-19T13:08:36-03:00

The largehead hairtail Trichiurus lepturus is an important fishery resource and a source of income for artisanal fishers in northeastern Brazil. In the region, this species has recently attracted the attention of investors considering its export to Asian countries. The aim of this research was to obtain data regarding reproductive biology to manage populations, as certain fishing gears usually caught juveniles. Specimens were obtained monthly from August 2017 to July 2018 from fixed traps in the municipality of Bitupitá, Ceará state, Brazil. A total of 437 specimens were sampled, ranging from 30.2 to 98.5 cm, including 255 females and 182 males. The sex ratio was 1:1.4 (M:F), with females predominating in larger length classes. The reproductive period occurs between August and December, coinciding with the dry season in the region. The species exhibits asynchronous oocyte development and batch spawning, with an average fecundity of 51,209 oocytes per batch. The results of this study are fundamental for characterizing and understanding the reproductive biology of T. lepturus, given its commercial importance in the region and the potential for increased catches targeting export markets. It was also observed that 37% of the specimens captured were below L50. This study represents an initial step in filling the knowledge gap in northeastern Brazil with reproductive data, enabling the establishment of management priorities for this important species.

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

2024-02-19T15:45:17-03:00

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.

Dietary aspects at the population and individual level of Pimelodus argenteus, a native fish species from the southern Pantanal, Brazil

2024-03-27T16:03:44-03:00

Pantanal is highly important environmentally and economically and suffers from environmental changes and anthropization. Pimelodus argenteus is a native species from the southern Pantanal and important for artisanal fishing and feeding of riverside populations. Given the assumptions, this study aimed to characterize the diet and feeding habits of P. argenteus and verify if there is variation and individual specialization in the diet in the evaluated period. For this, the specimens were acquired from an artisanal fisherman in October 2017 in the Miranda River, southern Pantanal, Mato Grosso do Sul state, Brazil. The population’s diet was variable, composed of 18 food items, and its trophic guild was determined as carnivorous/malacophagous. We observed individual variation and specialization in the diet at the individual level. The consumption of bivalves with high invasive potential and non-organic items was also observed, indicating anthropic influences. These results raise questions about the possible long-term impacts on the native and economically important species. In addition, we suggest that individual specialization may have occurred in response to competitive pressures. Finally, our results can contribute to ecological information and support conservation plans for this native species and this biome with important ecosystem functions.

Sustainability of pacific white shrimp culture strategies during a regional outbreak of white spot syndrome virus

2024-04-24T08:12:12-03:00

The present study evaluated economic, environmental and social sustainability of three production strategies of Pacific white shrimp (Litopenaeus vannamei) during a regional outbreak of white spot syndrome virus. The strategies mainly differed by stocking densities (92, 14, 8 larvae.m^-2; D92, D14, and D8, respectively), fertilizer inputs, and other general management. Each dimension of sustainability was evaluated using sets of indicators. The D14 and D8 strategies showed greater economic feasibility than D92 because of the reduced operational costs and investments to buy post-larvae and feed. All strategies showed moderate environmental sustainability but had weakened economic and social sustainability due to the virus. The D14 and D8 strategies received the highest overall sustainability index. The D92 was the most environmentally favorable management strategy and had a social tendency. In general, shrimp mariculture performed with a high initial stocking density cannot guarantee the return of invested capital. The lower density strategies were economically feasible due to the high prices paid per kilogram of shrimp as a function of the higher individual average weight. However, economic feasibility of these two strategies coincided with low creation of employment opportunities and income, decreased social sustainability, and increased environmental impact.

Effect the seaweed Sargassum filipendula and Ascophyllum nodosum on the resistance of the shrimp Litopenaeus vannamei to hypothermal shock

2024-04-22T13:58:44-03:00

This study investigated the resistance of Pacific white shrimp (L. vannamei) to hypothermal shock when treated with extracts from the brown seaweeds Sargassum filipendula and Ascophyllum nodosum, either by immersion for postlarvae or as a dietary supplement for juveniles. Post-larvae were exposed to seaweed extracts at concentrations of 20, 50, 100, and 200 mg*L⁻¹, while juveniles were fed diets with 0.5%, 2.0%, and 4.0% seaweed extracts for 10 days. For juveniles (~12 g), hemato-immunological and microbiological analyses were conducted after feeding with 5% seaweed diets for 15 days, all followed by hypothermal shock. Samples were collected prior to the start of thermal shock, immediately after shock (0 h), and 1 and 24 h after return to initial temperature. The aqueous extract of the seaweeds A. nodosum and S. filipendula at concentrations 100 mg*L⁻¹ and 200 mg*L⁻¹, respectively, improves the survival rates of post-larvae L. vannamei submitted to hypothermal stress. For juvenile shrimps, hypothermal shock causes significant immunodepression and reduces the bacterial community in the intestine. The addition of seaweed to the feed did not increase the survival rate and did not affect the intestinal microbiota of L. vannamei. In the case of immunological parameters, both species positively affect the agglutination titer, but no other parameters analyzed.

Dietary restriction associated with inorganic fertilization in fishponds on growth of Nile tilapia fingerlings

2024-06-10T14:06:39-03:00

The study evaluated muscle growth and performance in Nile tilapia fingerlings fed a restricted diet combined with phytoplankton in fertilized ponds. Four treatments were tested: 100% feed daily, 100% feed on alternate days, 50% feed daily + fertilization, and 50% feed on alternate days + fertilization. Fish were stocked at 19 fish/m² and fed a 45% protein diet. Ponds were fertilized weekly with superphosphate and ammonium sulfate, and water parameters were monitored. Growth, morphometrics, and histological analyses of dorsal and caudal muscles were performed at 0, 30, and 60 days. The 50% feed daily + fertilization treatment yielded similar weight gain, growth curves, and final lengths to the 100% feed daily group. Muscle growth through hyperplasia and hypertrophy was significantly higher (p < 0.05) in the 50% feed daily + fertilization group, supporting diverse phytoplankton communities, especially Chlorophyceae, Bacillariophyceae, and Cyanobacteria. These findings indicate that restricting feed to 50% of body weight with weekly fertilization maintains fish development, reduces feed costs, and promotes muscle growth while enhancing phytoplankton diversity in ponds. This approach offers a sustainable and cost effective strategy for tilapia farming.

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

2023-10-18T18:51:17-03:00

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

2024-05-21T05:36:18-03:00

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.

Length–weight relationships of the estuarine fish species in the second largest mangrove area in the world, Brazil

2024-05-15T15:20:09-03:00

Length-weight relationship (LWR) parameters are necessary to understand the life cycle of fish to describe the biological aspects of species. In this sense, LWRs were determined for 17 estuarine species from the second largest mangrove area in the world, Northern Brazil. The sampling was carried out during the dry and wet seasons of 2015 and 2018 in 3 estuaries described as conservation units in the rivers Pará, Caeté, and Parnaíba. Fish were collected by using manual beach seine, block nets and sieves. Overall 488 specimens were analyzed using the equation W = a TL^b. The a values ranged from 0.000001 to 0.000019 and b values ranged from 2.7230 to 3.2821. This study brings new data on estuarine fish from Brazil with additional information contributing to the conservation and management of the fish stocks.

Inclusion of protein hydrolysate extracted from bycatch in the diet of the Malaysian giant prawn: effects on physiology

2024-04-16T13:41:26-03:00

Bycatch refers to all the animals caught with species of economic interest. These economically unattractive animals are later discarded at sea. Protein hydrolysate with antioxidant potential was extracted by our research group from two main fish species (Paralonchurus brasiliensis and Micropogonias furnieri) of the shrimp fishing bycatch fauna of the São Paulo coast, Brazil. This study tested the inclusion of different concentrations of hydrolysate (0.0, 2.5, 5.0, and 10.0%) in the diet of Macrobrachium rosenbergii. Survival, growth, and physiological processes (ingestion, defecation, hepatosomatic index, O:N ratio, metabolism, and ammonia excretion) were assessed. The inclusion of hydrolysate did not affect crucial parameters for aquaculture, such as survival, growth (about 2% in relation to initial biomass), intake, and mechanisms related to obtaining and using energy (hepatosomatic index and protein as main type of energy substrate oxidized). Metabolism and nitrogen excretion were reduced (~70%) in all treatments with hydrolysate, suggesting lower energy requirements for digestion and absorption of nutrients, as well as the optimization of animal protein use. We recommend the inclusion of 2.5% hydrolysate for future work to test the antioxidant capacity of hydrolysate in M. rosenbergii. This concentration level does not alter important physiological parameters and is cost-effective.

Can commercial aquafeeds improve the nutritional value of brine shrimp? Proximal composition and lipid profile of alternative enhancers

2024-06-24T15:17:54-03:00

Artemia, commonly known as brine shrimp, holds a significant role as live prey in ornamental and commercial fish aquaculture. This study addressed the nutritional deficiency in adult Artemia biomass, exploring alternative enrichers available in Brazil. Evaluating a commercial aquafeed (Polinutre Poli Camarão 400PL) and a lipid emulsion (BioViv HUFA Continum), adult Artemia were subjected to different enrichment protocols, including periods of 1, 12, and 24 hours with each enricher, as well as a test group raised 100% on the commercial feed. Protein content for Artemia exclusively fed the commercial aquafeed (CF100) reached values very similar to those provided by the main commercial products available worldwide and other commonly used live prey. Enrichment time effects were observed from 12 h onwards, showing positive impacts on protein accumulation. Lipid content peaked at 12 h, followed by a decrease at 24 h. Further studies are needed to assess whether the combination of feed-based protocols followed by 12-h lipid emulsion enrichment can surpass the current results, providing high levels of protein content while maintaining a complete lipid profile.

Fungi influence in the chemical composition, textural quality, buoyancy, and floatation time of poorly stored fish feeds

2024-07-29T14:35:01-03:00

This study assessed the effects of fungal contamination on the chemical composition, texture, buoyancy, and floating time of poorly stored fish feed. Among 21 commercial and six artisanal feed samples analyzed, 81% showed fungal growth. Nutritional losses were significant: commercial feeds lost 41.97–50.61% of minerals, 17.11–21.69% of crude protein, 38.28% of lipids, 35.16–50.66% of carbohydrates, and 37.77% of raw energy. Artisanal feeds experienced even greater losses, with reductions of 66.12–84.06% in minerals, 43.29–47% in crude protein, and 25.60–42.40% in raw energy. Contamination altered pellet texture, causing hardening, crumbling, and increased fracturability in water, reducing buoyancy (~50%) and causing nutrient leaching. This led to feed accumulation at pond bottoms, accelerating eutrophication. These findings emphasize the economic and environmental risks of fungal contamination in fish farming. Proper storage with humidity and temperature control is crucial to prevent fungal growth, nutrient loss, and mycotoxin contamination.

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

2024-02-05T10:35:48-03:00

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 dietary oyster mushroom on intestinal histology, growth performance, and immuno-serological parameters of juvenile rainbow trout

2024-08-07T14:18:09-03:00

In this study, the effects of nutritional supplementation with oyster mushroom extract on the nonspecific immune response, gut histology, and growth performance of rainbow trout were investigated. Sixty fish (weighing 20 g) were placed in tank groups, and groups were established. The control fish were fed with commercial pellets, and the other two experimental group fish were fed with experimental diets containing oyster mushroom extracts for six weeks. During the trial, biometrical, immunological, and biochemical parameters were assessed in one, two, three, four, five, and six weeks. Also, gut samples were taken at the same sampling weeks. The intracellular respiratory burst, bactericidal activity, total protein, and globulin were significantly enhanced in fish fed 2% experimental diet in three, four, five, and six weeks. Compared to the control group, the fish group which received 2% supplemented diet showed elevated cholesterol levels in serum at the first week followed by decrease in the third and sixth weeks. Some biochemical parameters (glucose, albumin, and triglycerides) were not affected. Moreover, the feeding with dietary extract did not show any negative impact on the histology of the gut and growth performance of fish. These results indicated oyster mushroom extract may effectively enhance non-specific immune parameters in juvenile rainbow trout.

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

2024-03-06T10:30:12-03:00

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.

Cage fish farm causes the homogenization of wild fish diets of different sizes

2023-11-01T11:09:51-03:00

We evaluated the influences of cage fish farm on the individual diet of Geophagus sveni, a wild species nonnative to the Paraná river basin, and hypothesized that, in areas where there are no cage fish farms (CT), differences in feeding occur between larger and smaller individuals. In addition, in cage fish farm areas (CF), there are no differences in feeding between smaller and larger individuals due to the consumption of pelleted feed. For this, we evaluated the stomach contents of individuals of different body sizes sampled in CT and CF areas. We observed significant differences in diet between larger and smaller individuals only in the CT area, corroborated by positive and negative relationships between food items and standard length. In the CF area, we observed pelleted feed consumption by individuals of different sizes and only positive relationships between food items and standard length. Thus, the cage fish farms interfered with the consumption of natural food resources, promoting a more homogeneous diet among smaller and larger individuals. In this context, because of the importance of trophic segregation for intrapopulation coexistence and population stability, this homogenization can promote an imbalance in population dynamics.

Seaweed inclusion in artificial diet of purple sea urchin Paracentrotus lividus: effects on somatic and gonadal development

2024-02-26T16:58:15-03:00

This work evaluated the inclusion of seaweed in artificial diet of Paracentrotus lividus sea urchins weighing between 11 and 14 g to test its effect on growth and gonadal yield. Initially, multiple-choice feeding preference assays were conducted using 20% fresh and dried specimens of Laminaria digitata, Sargassum muticum, and Ulva lactuca seaweeds incorporated into an artificial diet. Then, over the course of 20 weeks, experiments comprised of four different diets were carried out, including one for each seaweed incorporated into the artificial diet. Afterwards, sea urchins were weighed to evaluate somatic growth. From the eighth week onwards, animals were selected for gonadosomatic index and gonad coloration analyses. In the feeding preference test, fresh and dried L. digitata showed the best results. In test with seaweed incorporated into the artificial diet, the preference was for diets containing L. digitata and S. muticum. Both diets also promoted a higher gonadosomatic index than that of the control at the end of the experiment. Therefore, it can be concluded that the inclusion of L. digitata and S. muticum in the artificial diet of sea urchins can act as a food stimulant to improve growth performance.

ECOSYSTEM INDICATORS TO ASSESS THE SUSTAINABILITY OF MULTISPECIFIC ARTISANAL FISHERIES IN FACE OF ENVIRONMENTAL CHANGES IN THE AMAZON BASIN SOUTH

2024-06-19T15:16:51-03:00

The construction of hydroelectric dams causes several impacts on the aquatic environment and affects its structure and functions with direct consequences for the provision of ecosystem services. Despite its importance, since 1970, fisheries in the Amazon region, especially small-scale artisanal fisheries practiced by traditional populations, have been facing serious problems arising from human and climatic actions. In this study, we evaluated the impacts of dam construction and the environmental responses on fisheries production and fishing sustainability indexes in the Madeira River, which is the largest tributary of the Amazon River, between 2000 and 2019. Fisheries landing data in the city of Porto Velho and large-scale environmental variables were collected for each of the years in the period and were compared using general linear models. We found that dams, as well as changes in hydrological levels, affect fisheries production. The sustainability indexes showed a decline after the completion of the two dams. Moreover, catch-per-unit-of-effort showed a significant decline after the implementation of the dam. We therefore highlight the importance of understanding the factors that affect the sustainability of fisheries in large rivers in order to mitigate the impacts of large dams and other anthropogenic actions.

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

2024-01-17T12:56:04-03:00

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

2023-10-18T18:56:16-03:00

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.

Bacillus improves the health and growth performance of Penaeus vannamei in an intensive nursery without water exchange

2024-06-19T09:23:01-03:00

The objective of this study was to investigate the effect of a bioremediator on the production of juveniles (Penaeus vannamei) in intensive nursery systems, on the zootechnical performance, water quality and health status of the animals. Two groups were used (control and bioremediation). In the treatment with bioremediator, 0.1g.m⁻³ of the product Arkhon Aqua® (Bacillus subtilis, B. licheniformes, B. amyloliquefaciens, B. megaterium) was applied daily, at concentrations of 1.0 x 10⁻¹¹ UFC.g⁻¹). The physical-chemical parameters of the water were monitored; health status, through presumptive analyzes evaluating the shape and filling of the hepatopancreas tubules and the prevalence of dirt on the gills and quantified Vibrios spp. and total heterotrophic bacteria in water and juveniles. The bioremediator provided a significant reduction in the volume of total dissolved solids (36.9%), settleable solids (68.9%) and the presence of organic matter in the gills (50.0%), in addition to showing an increase in the final mean weight (28.3%) and yield (20.0%), in addition to reducing feed conversion (18.7%) than control group. The bioremediation demonstrated a higher concentration of Vibrios spp. in water, however, it did not influence the concentration of Vibrios spp. in juveniles. It is concluded that the bioremediator improved the culture water, consequently enhancing the zootechnical performance of the shrimp.

Diet and seasonal distribution of piranha populations in the São Miguel River, Rondônia, Brazil

2024-09-04T20:05:47-03:00

This study analyzed the spatial and seasonal distribution of piranha species and their respective diets. Samples were collected monthly from August 2020 to July 2021 using various types of fishing gear in different sections of the river. Limnological data were also analyzed to assess correlations with the distribution of piranha species. A total of 326 fish were identified, encompassing nine species and three genera. The most abundant species were Serrasalmus rhombeus (N = 155), Pygocentrus nattereri (N = 89), and Serrasalmus spilopleura (N = 23), which were found in the headwaters, intermediate section and river mouth, respectively. The stomach contents of 56 piranhas were analyzed and revealed that 55.35% of the stomachs were full and 44.65% were empty. The results indicated that fish remains were the most relevant food items at all the collection points. The results demonstrated spatial effects among the fish communities in the headwaters, intermediate section and river mouth, along with variations in water levels, with differences between high- and low-water periods. The redundancy analysis indicated significant effects for temperature, but not for other water parameters. It can be concluded that the piranha populations of the São Miguel River are distributed according to the water levels and the different sections of the river, though they utilize the same type of food resource.

Prebiotic, probiotic and marine algae suplementation in juvenile tilapia diet

2023-11-13T09:56:23-03:00

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.

Functional assessment of citral dietary supplementation on growth performance, intestinal parameters, and specific activity of the digestive enzymes of Sardinella brasiliensis reared in recirculating aquaculture system

2024-10-16T11:29:05-03:00

This study evaluated the effects of dietary supplementation with citral on growth performance and intestinal parameters, and specific activity of the digestive enzymes of Sardinella brasiliensis. 240 juvenile S. brasiliensis were randomly distributed in a recirculating aquaculture system (RAS) composed of 12 circular tanks of 150 L (n = 20 per tank). A diet without citral addition (control) and three diets containing different levels of citral inclusion (0.5, 1.0 and 2.0 mL kg*feed^–1) were used in the fish feeding management during 20 days. The indexes of zootechnical performance, survival, weight gain, specific growth rate, feed conversion and condition factor of the fish were verified, as well as digestive enzymes and histological analysis. A significant positive relationship was found between citral supplementation and fish survival. In the specific activity of digestive enzymes, dietary citral supplementation at 2.0 mL* kg feed^–1 increased lipase and amylase activity. Citral supplementation positively influenced the number of villi and intestinal crypt depth. Furthermore, the inclusion of citral at 0.5 mL kg*feed^–1 increased the intestine diameter of the fish. The results of the experiment suggest that the addition of citral as an additive in the diet of S. brasiliensis improved the survival of fish.

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

2024-04-04T16:56:50-03:00

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.

Reproduction of the dog snapper Lutjanus jocu in captivity, linking ecological, and production observations

2024-07-29T09:59:25-03:00

Snappers’ domestication for reproductive purposes is a first step to allow future offering of high quality, more sustainable fish products, generating ecological advantages to the marine ecosystem such as the reduction on the pressure of current stocks. The dog snapper Lutjanus jocu is a very important species with very little information on its capability for domestication. For that reason, dog snappers were collected in the coastal area and maintained in laboratory to verify their capacity to be domesticated and achieve reproductive success. A specific protocol was designed for their maintenance in recirculating aquaculture systems and is presented in the methods section. The domestication of wild specimens until they achieved reproductive success and produced viable eggs in captivity took approximately 2.5 years. Spawning events produced an average of about 25,000 eggs, or about 2,100 eggs·kg^-1of broodstock, with an average of three events per week. During new and full moon, the viability of eggs was higher, showing a strong influence of the lunar cycle in their reproduction. Spawning activities only happened during the night, and embryo development took about 535 degree-hours. Our results concluded that the dog snapper L. jocu can be conditioned in captivity for reproductive purposes, with consistent production of eggs in a weekly basis, enabling the possibility of a large-scale production to help reduce the pressure on the natural stocks.

Diet of Nile tilapia in the Cachoeira Alta do Tarumã stream, Tarumã-Açu hydrographic basin (Manaus, Amazonas, Brazil)

2024-04-15T09:42:19-03:00

Trophic plasticity is an important factor in assessing the ability of a species to remain in an altered environment or its ability to be introduced into a new environment. The Nile tilapia is a species that has been illegally introduced for aquaculture purposes in the central portion of the Amazon. Its escape into the natural environment has occurred, and it is already possible to find specimens in streams around Manaus, capital of the state of Amazonas, Brazil. This study aimed to investigate the diet of Nile tilapia in the stream known as Cachoeira Alta do Tarumã (Manaus, Amazonas, Brazil), a small tributary of the Tarumã-açu river that has been affected by anthropogenic actions. To identify its feeding habit, 43 stomachs were analyzed according to their degree of repletion, frequency of occurrence of food items, volumetric method, and the food importance index. The species was identified as being detritivores with a tendency to herbivory. Plastic was identified in the diet of this species, which indicates generalist and opportunistic habits when inserted in habitats with a low supply of food.

Socio-environmental and economic impacts due to the disaster at Vale S.A. in Brumadinho, MG, Brazil: A systematic review

2024-01-05T15:44:35-03:00

Significant socio-environmental and economic impacts on fishermen and fish farmers in the Três Marias reservoir arose from the collapse of the mining tailings dam in the municipality of Brumadinho, MG, Brazil, in 2019. To help assess this situation, we carried out a systematic review to find information that scientifically documents these impacts. To this end, we used the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Journal Portal, accessed through the Federated Academic Community, to search for data indexed between 2019 and 2023, in the following databases: Web of Science, Scopus, and CAB Direct. We used Brumadinho as the central keyword and linked to it 25 other secondary keywords, such as environmental disaster, fishermen, fish farmers, and Três Marias dam. To screen and select the results, we used Rayyan software and the Preferred Reporting Items for Systematic reviews and Meta-Analyses methodology. The search resulted in 990 articles, 61 theses, and 251 dissertations. Among them, only 26 articles, 19 theses and 66 dissertations were eligible as contributions to the topic, but very few reported the situation of fishermen and fish farmers. We concluded that there is a lack of information on the damage suffered by these people, and that more scientific studies and attention to this public are needed.

Fish hematology in Brazil: A review

2024-08-22T16:15:30-03:00

This article reviews data of Brazilian manuscripts on fish hematology in their natural environment (rivers, dams, lakes, and sea) and captivity, their relationship with parasitism, temperature, stress, nutrition, and water quality. A total of 205 articles were researched, of which 17 were published before the year 2000. Fish hematology has always been less studied than other classes of vertebrates, but blood analysis can provide information about disease processes in these animals. Although the robust interpretation of fish blood parameters is often hampered by the lack of reference values, this knowledge deficit represents an opportunity to expand clinical hematology studies across fish species. Fish hematologists are encouraged to obtain samples whenever possible as they may benefit individual animals or populations, contributing to the establishment of baseline data for many species not yet studied. Efforts are necessary to advance in this field of study clarifying some important points such as the function of each leukocyte and relating plasma changes to the species physiology.