Tavani Rocha Camargo

Fisheries bycatch, while representing a major ecological concern due to the incidental capture of non-target species, also constitutes an underexplored source of marine biomass with biotechnological potential. This study aimed to generate and characterize bioactive peptides from the muscle tissue of three common bycatch species from the Brazilian coast: Paralonchurus brasiliensis, Micropogonias furnieri, and Hepatus pudibundus. Muscle homogenates were hydrolyzed using either Alcalase or Protamex to produce peptide-rich hydrolysates, which were analyzed through SDS-PAGE, HPLC-UV, MALDI-TOF, and LC-MS/MS. De novo sequencing and bioinformatic analyses predicted bioactivities that were subsequently validated by in vitro assays. The results demonstrated that enzyme selection strongly influenced both peptide profiles and bioactivity. The Protamex hydrolysate of P. brasiliensis (PBP) exhibited potent antifungal activity, inhibiting Candida albicans growth by 81%, whereas the Alcalase hydrolysate (PBA) showed moderate inhibition of Staphylococcus aureus (29%). No significant effect was observed against Escherichia coli. Overall, this study highlights a sustainable strategy for the valorization of fisheries bycatch through the production of bioactive marine peptides and identifies P. brasiliensis hydrolyzed with Protamex as a promising source of anti-Candida peptides for pharmaceutical and nutraceutical applications.

Effective sustainable fish farming necessitates enhanced models that incorporate environmental variability and contemporary monitoring methods. This research presents an innovative framework for assessing and modeling the environmental carrying capacity based on phosphorus (ECCp) in tropical and neotropical lakes and reservoirs. The model evaluates phosphorus waste from tilapia farming (Oreochromis niloticus) under diverse climatic conditions and production scenarios in cage systems. Using bioenergetic modeling and Monte Carlo simulations, we estimated phosphorus retention in fish and maximum production limits across different temperatures (21 °C, 25 °C, 29 °C) and dietary phosphorus concentrations (0.8%, 1.2%, 2.1%) in Brazil’s Chavantes reservoir. Results indicated that phosphorus retention diminished with higher dietary phosphorus and increased temperatures, ranging from 51% (0.8% P) to 20% (2.1% P). Phosphorus discharge ranged from 3.3 to 20.5 kg/ton of fish produced. The ECCp model forecasted an allowable production of roughly 40 tons per year at full operational capacity, reflecting a 41% increase compared to current regulations. The model’s accuracy (96%) surpassed that of traditional regulatory frameworks, which rely on static parameters, emphasizing the shortcomings of existing practices. The findings promote enhanced modeling strategies, sophisticated monitoring, adaptive management, and revised public policies to mitigate phosphorus emissions and support sustainable aquaculture in tropical and neotropical regions.

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.

Aquatic plants have a high potential to be used as eco-friendly technology in fish farming effluent treatment systems. However, there is still a reduced use of the vegetable biomass produced in these treatment systems. Thus, the aim of this study was to develop an alternative feed with the aquatic plant Azolla pinnata to take advantage of plant biomass, reusing the plant to develop a new product and promote a circular economy. A. pinnata was implemented in decantation pond that receives effluents from fish farming. Samples were collected weekly at four times (0, 7, 14, and 21 days). Posteriorly, A. pinnata was processed to obtain the meal. Azolla meal was offered along with three commercial feed (24%, 28% and 32% of the crude protein) in an experiment to evaluate the zootechnical performance of tilapia in small tanks. The results indicated that A. pinnata was efficient to retention of phosphorus and nitrogen after seven days. In the experiment with animals, the treatment using commercial feed with 28% of the crude protein + Azolla showed the best efficiency rates for using the diet. Thus, the use of the A. pinnata meal was a viable alternative in the search for sustainable products to promote a bioeconomy in the small fish farms.

The commercialization of ornamental aquatic organisms stands out among the various segments of the Pet market in Brazil. Among the various species used for aquarium hobby, the colored carp, known as Koi or Nishikigoi (Cyprinus Carpio L.), represent the main species commercialized in the country. In this context, the present study carried out a projection of the economic viability of Nishikigoi carp production in a fish farm in the metropolitan region of São Paulo that sells animals to the Brazilian Pet market for ornamental fish. Three hectares of water depth were evaluated during ten production cycles per year. In this period, the total production costs (TC) and effective operating costs (EOC) and total operating costs (TOC) were obtained, plus fixed costs for the operation of this agribusiness. Economic indicators were applied to assess the feasibility of investing in the business through the internal rate of return (IRR), net present value (NPV), payback period (PRC) and cost-benefit ratio of the investment (RCB). The initial investment projection was 2.3 million reais. The most expressive economic viability indicators were obtained by the IRR of 10.41% per year and NPV of approximately 1.6 million reais, considering the net cash flow for the period of ten years. The payback period on invested capital can be reached in 7.15 years with an RCB of 1.68 reais. In this way, the scenario studied demonstrates the feasibility of investing in this agribusiness being a promising venture in the aquaculture sector.

The animals from bycatch of the shrimp fisheries can be a source of natural products and bioactive compounds. Thus, the present study aimed to evaluate the bioactivity of protein hydrolysates prepared from the two most abundant crabs from the bycatch of shrimp fisheries in Brazil (Callinectes ornatus and Hepatus pudibundus). Samples of C. ornatus and H. pudibundus were collected in the region of Ubatuba, State of São Paulo, Brazil. Muscles with small pieces of exoskeleton of both species were hydrolyzed using two enzymes, Alcalase 2.4 L® or Protamex®. The in vitro antioxidant capacity was analyzed used three methods: DPPH, sulfhydryl groups, and peroxyl radicals. Additionally, the cytotoxicity of the hydrolysates was investigated using pre-osteoblasts cells. The results showed that the degree of hydrolysis (DH) of H. pudibundus was superior to DH of C. ornatus using both enzymes and was higher when using the enzyme Alcalase 2.4 L® (32.0% ± 1.9). The analysis suggested that the hydrolysates have antioxidant activity. Besides that, no cytotoxic effect was observed on cell viability. Thus, protein hydrolysates of C. ornatus and H. pudibundus have bioactivity, which add value to these bycatch species and suggests their potential use as nutraceutical ingredient in the food industry. Graphic Abstract

In this study, we evaluated the effect of complexation and microencapsulation with pea protein on the antioxidant activity of protein hydrolysates from bycatch in Brazil. The zeta potential values of complexes changed from negative to positive with the increase of pea protein as a result of positively charged complexes formation. The increase in the ratio of pea protein/hydrolysates also resulted in increased turbidity in all samples. Particle size measurements indicated that the complexes tended to form larger aggregates (ranged from 61.5 ± 1.7 μm to 183 ± 2.8 μm). The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the pea protein/fish protein hydrolysate complexes was higher than that of the protein hydrolysates alone. Moreover, increasing levels of pea protein did not affect the antioxidant activity of fish protein hydrolysates. The complexes of the Paralonchurus brasiliensis were chosen for the microencapsulation process by spray-drying. The results revealed that spray-drying did not have a significant effect (P > 0.05) on the protein hydrolysate antioxidant activity when they were complexed with pea protein. Thus, this work suggests that the complexation with pea protein and subsequent microencapsulation by spray-drying is an efficient way to protect the biological activity of protein hydrolysates obtained from bycatch. This study provides evidence for the potential use of bycatch from shrimp fisheries as functional ingredients or nutraceuticals.

The families Aethridae and Calappidae were originally considered as part of the same family; however, their morphology and molecular biology separate them into two families. In this context, we describe the ultrastructure of spermatozoa of species of the Calappidae, Aethridae and Menippidae to elucidate the relationships among taxa. The vasa deferentia were submitted to routine protocols for transmission electron microscopy. Our results indicate that the morphology of the spermatozoa of Hepatus pudibundussupports its exclusion from the Superfamily Calappoidea due to the presence of the apical striated layer. The spermatozoa of Menippe nodifrons is very similar to H. pudibundus and corroborates the recent phylogenetic analysis using sequence data of nuclear genes. Moreover, our results evidence two morphological patterns of spermatozoa within Calappidae. Calappa ocellata and C. cinerea show spermatozoa with a wide acrosome vesicle, a thick operculum shaped as a shallow “W” and a large thickened ring. Calappa gallusand C. hepatica show spermatozoa with a longer acrosome vesicle, a pointed operculum and a slender thickened ring. Our ultrastructure results conform with previous molecular proposal and show that spermatozoa ultrastructure can be an effective tool to adjust phylogenetic relationship when used in association with molecular data.