Because of its high nutritional value, palatability and increased digestibility, fishy meal is widely used as an animal protein source in the aquafeed industry. However, the resource shortages and ...rising prices seriously restrict the use of fish meal (FM) in aquaculture. In this light, much efforts have been conducted to seek the sustainable supplies of protein sources to substitute FM. Due to their relatively low protein content and palatability, the presence of anti‐nutritional factors (ANFs) and unbalanced amino acid profiles, the plant protein sources have been limited in aquafeed, whereas the animal protein sources can replace FM in aquafeed due to their high protein content, total digestible dry matter and lack of ANFs. The fermentation process was recognized for its role in improving the nutritional quality of animal and plant protein sources. The protein sources can be treated with appropriate microorganisms to preserve its nutrients and finally incorporated into aquafeed, which would reduce feed costs and environmental pollution. Fermented meals showed better nutrient efficiency and could improve the nutritional value of aquafeed. This review was intended to present more updated information about the application of fermented ingredients in aquafeed industry. Based on the data collected, this review will contribute to further research into the production of fermented feed as a functional feed for sustainable aquaculture.
Reef fish assemblages under fishing pressure generally exhibit a lower fish biomass, abundance, and size structure, which can be counteracted with the creation of marine protected areas (MPAs). The ...effectiveness of MPAs relies on enforcement and compliance, which is particularly challenging in developing countries with financial and socioeconomic limitations. By combining underwater visual surveys (UVS) and baited remote underwater video stations (BRUVS), we determined the abundance, size distribution, and biomass of economic (e.g., target and ornamental species) and ecological (e.g., small/large predators and herbivorous) indicator fish groups inside and outside a no-take MPA from the north Pacific coast of Costa Rica. The biomass of economic fish groups was not affected by protection, yet overall abundance and size distribution of fishes differed between no-take and open-fishing zones. These results suggest that although illegal fishing may be occurring inside the MPA, there are at least partial benefits of protection on particular groups within the fish assemblage. Herbivores and ornamental fishes, two groups that are targeted by the artisanal compressor fishery and by the aquarium trade, respectively, had higher biomass and were more abundant inside the no-take MPA. Additionally, large shark species (e.g.,
Galeocerdo cuvier
,
Carcharhinus leucas
,
C. limbatus
) were only present inside the MPA. Habitat quality was particularly important for ornamental fishes which showed higher biomass in areas with high coral cover. Our study adds to a growing body of evidence suggesting that, even with limited enforcement, MPAs still provide ecological benefits for reef fish assemblages.
With the ongoing loss of coral cover and the associated flattening of reef architecture, understanding the links between coral habitat and reef fishes is of critical importance. Here, we investigate ...whether considering coral traits and functional diversity provides new insights into the relationship between structural complexity and reef fish communities, and whether coral traits and community composition can predict structural complexity. Across 157 sites in Seychelles, Maldives, the Chagos Archipelago, and Australia’s Great Barrier Reef, we find that structural complexity and reef zone are the strongest and most consistent predictors of reef fish abundance, biomass, species richness, and trophic structure. However, coral traits, diversity, and life histories provided additional predictive power for models of reef fish assemblages, and were key drivers of structural complexity. Our findings highlight that reef complexity relies on living corals—with different traits and life histories—continuing to build carbonate skeletons, and that these nuanced relationships between coral assemblages and habitat complexity can affect the structure of reef fish assemblages. Seascape-level estimates of structural complexity are rapid and cost effective with important implications for the structure and function of fish assemblages, and should be incorporated into monitoring programs.
The early stages of fish during their life cycle, including larvae and juveniles, are sensitive to the environment. Determining the occurrences of fish larvae and juvenile relative to their ...associated environments is essential for conservation and fisheries management. Computer-based modeling has rarely been applied for forecasting the distribution patterns of the early fish stages in dynamic systems such as estuaries. In the present study, we applied novel modeling techniques to fish larval and juvenile samples collected in May, September, November, and December during 2019 along the Ba Lat estuary of the Red River, northern Vietnam. The results showed that the occurrences of freshwater and marine fish larvae and juveniles were inversely related to environmental factors (electrical conductivity, temperature, pH, depth, shore distance and turbidity) with a high square of multiple correlation coefficients. The occurrences of the two fish groups were strongly related to temporal and spatial changes in the estuary, and these correlations could be utilized for machine learning processing. Linear regression, Gaussian process models, ensemble regression, and artificial neural network (ANN) models were applied to elucidate the distributions of fish larvae and juveniles. It shows that ANN models obtained the highest
R
2
(> 0.63). In addition, the spatial distribution prediction of fish larvae and juveniles using ANN models was similar to the field measurement. Thus, we suggest utilizing ANN models to predict the occurrences of early fish stages in estuaries in tropical regions such as Vietnam. Recommendations for further applications of ANN models are also given in this study.
In the present manuscript, various by-products (heads, trimmings, and frames) generated from salmonids (rainbow trout and salmon) processing were evaluated as substrates for the production of fish ...protein hydrolysates (FPHs), potentially adequate as protein ingredients of aquaculture feeds. Initially, enzymatic conditions of hydrolysis were optimized using second order rotatable designs and multivariable statistical analysis. The optimal conditions for the Alcalase hydrolysis of heads were 0.1% (v/w) of enzyme concentration, pH 8.27, 56.2°C, ratio (Solid:Liquid = 1:1), 3 h of hydrolysis, and agitation of 200 rpm for rainbow trout and 0.2% (v/w) of enzyme, pH 8.98, 64.2 °C, 200 rpm, 3 h of hydrolysis, and S:L = 1:1 for salmon. These conditions obtained at 100 mL-reactor scale were then validated at 5L-reactor scale. The hydrolytic capacity of Alcalase and the protein quality of FPHs were excellent in terms of digestion of wastes (V
> 84%), high degrees of hydrolysis (
> 30%), high concentration of soluble protein (Prs > 48 g/L), good balance of amino acids, and almost full
digestibility (Dig > 93%). Fish oils were recovered from wastes jointly with FPHs and bioactive properties of hydrolysates (antioxidant and antihypertensive) were also determined. The salmon FPHs from trimmings + frames (TF) showed the higher protein content in comparison to the rest of FPHs from salmonids. Average molecular weights of salmonid-FPHs ranged from 1.4 to 2.0 kDa and the peptide sizes distribution indicated that hydrolysates of rainbow trout heads and salmon TF led to the highest percentages of small peptides (0-500 Da).
Interleukin-18 (IL-18) is a pro-inflammatory cytokine that belongs to the interleukin-1 (IL-1) family of cytokines. As occurs with IL-1β, it is synthetized as an inactive precursor peptide that is ...mainly processed by the cysteine protease caspase-1 in the inflammasome complex. In mammals, and in collaboration with IL-12, it has been described as an important cytokine controlling the Th1-mediated immune responses through the induction of IFN-γ. Although its function in mammals is well stablished, the activity of this cytokine in teleost remains to be elucidated. This could be due, among other things, to the absence of this gene in the fish model species zebrafish, but also to its complex regulation. As it was observed for rainbow trout and human, il18 splicing variants were also found in turbot, which could represent a regulatory mechanism of its bioactivity. In the case of turbot, three splicing variants were observed (SV1-3), and one of them showed an insertion of 10 amino acids in the middle of the potential caspase-1 cleavage position, reflecting that this is probably a form resistant to the processing by the inflammasome. Phylogenetic and three-dimensional analyses of turbot Il18 revealed that it is relatively well-conserved in vertebrates, although only a partial conservation of the gene synteny was observed between fish and mammals. As it was expected, turbot il18 splicing variants were mainly expressed in immune tissues under healthy conditions, and their expression was induced by a bacterial challenge, although certain inhibitions were observed after viral and parasitic infections. In the case of the viral challenge, il18 downregulations did not seem to be due to the effect of type I IFNs.
•Three il18 splicing variants were identified in S. maximus (SV1-3).•Turbot Il18 conserves the typical characteristics of the IL-1 family members.•Turbot il18 was mainly expressed in immune tissues.•Bacterial infection induced the expression of il18.•Viral and parasitic challenges inhibited il18 expression.
Due to its unique properties, collagen is used in the growing fields of pharmaceutical and biomedical devices, as well as in the fields of nutraceuticals, cosmeceuticals, food and beverages. Collagen ...also represents a valid resource for bioplastics and biomaterials, to be used in the emerging health sectors. Recently, marine organisms have been considered as promising sources of collagen, because they do not harbor transmissible disease. In particular, fish biomass as well as by-catch organisms, such as undersized fish, jellyfish, sharks, starfish, and sponges, possess a very high collagen content. The use of discarded and underused biomass could contribute to the development of a sustainable process for collagen extraction, with a significantly reduced environmental impact. This addresses the European zero-waste strategy, which supports all three generally accepted goals of sustainability: sustainable economic well-being, environmental protection, and social well-being. A zero-waste strategy would use far fewer new raw materials and send no waste materials to landfills. In this review, we present an overview of the studies carried out on collagen obtained from by-catch organisms and fish wastes. Additionally, we discuss novel technologies based on thermoplastic processes that could be applied, likewise, as marine collagen treatment.
Interleukin-17 (IL17) family cytokines are well known for having pro-inflammatory actions as important mediators of mucosal immune responses and are tightly regulated by various kinds of signals. ...However, most studies of IL17 genes have focused on mammals, and much less is known about IL17 genes in fish species. To better understand the scope and actions of the IL17 gene family in common carp, we characterized seven IL17 gene homologs from genomic and transcriptomic databases that could be classified into three subclasses according to different comparative genomic analyses. Phylogenetic analysis revealed that most IL17s are highly conserved, though recent gene duplication and gene loss events do exist. Through observation, we found that IL17D has undergone gene duplication in common carp and that all the IL17E genes were lost in vertebrates except mammals. The expression patterns of IL17 genes in common carp were examined during early developmental stages and in various healthy tissues, and the results indicated that most IL17 genes are ubiquitously expressed during early development and show particular tissue-specific expression in various healthy tissues, with relatively high levels in the spleen, liver, and kidney. To gain insights into the mucosal actions of inflammatory processes, the expression profiles of IL17 genes in gills from common carp were investigated after experimental challenge with Aeromonas hydrophila. After A. hydrophila infection, most IL17 genes were upregulated at 4 h postinfection in the gill and then gradually declined, while IL17A/F2 and IL17N were generally upregulated at 12 h postinfection, and IL17D2 maintained an increasing tendency. In contrast, IL17D showed the third phenomenon, rising expression, suggesting that immunogenes have different response strategies to bacterial invasion. Overall, the expression of IL17 in unstimulated tissues and toxicity attack test results demonstrated that these genes play critical roles under normal conditions and during bacterial infection. Moreover, this common carp IL17 gene family research provides a genomic resource for future studies on IL17 gene evolution, fish disease management and immune regulation.
•A complete set of seven interleukin-17 genes was identified in common carp.•Gene duplication and gene loss was observed in the interleukin-17 family.•Differentially expressed of interleukin-17 genes were identified after bacterial infection.
Nutrient absorption is essential for animal survival and development. Our previous study on zebrafish reported that nutrient absorption in lysosome-rich enterocytes (LREs) is promoted by the ...voltage-sensing phosphatase (VSP), which regulates phosphoinositide (PIP) homeostasis via electrical signaling in biological membranes. However, it remains unknown whether this VSP function is shared by different absorptive tissues in other species. Here, we focused on the function of VSP in a viviparous teleost
, whose intraovarian embryos absorb nutrients from the maternal ovarian fluid through a specialized hindgut-derived pseudoplacental structure called trophotaenia.
VSP (Xe-VSP) is expressed in trophotaenia epithelium, an absorptive tissue functionally similar to zebrafish LREs. Notably, the apical distribution of Xe-VSP in trophotaenia epithelial cells closely resembles zebrafish VSP (Dr-VSP) distribution in zebrafish LREs, suggesting a shared role for VSP in absorptive tissues between the two species. Electrophysiological analysis using a heterologous expression system revealed that Xe-VSP preserves functional voltage sensors and phosphatase activity with the leftward shifted voltage sensitivity compared with zebrafish VSP (Dr-VSP). We also identified a single amino acid variation in the S4 helix of Xe-VSP as one of the factors contributing to the leftward shifted voltage sensitivity. This study highlights the biological variation and significance of VSP in various animal species, as well as hinting at the potential role of VSP in nutrient absorption in
trophotaenia.
We investigate the voltage-sensing phosphatase (VSP) in
, a viviparous fish whose intraovarian embryos utilize trophotaenia for nutrient absorption. Although
VSP (Xe-VSP) shares key features with known VSPs, its distinct voltage sensitivity arises from species-specific amino acid variation. Xe-VSP in trophotaenia epithelium suggests its involvement in nutrient absorption, similar to VSP in zebrafish enterocytes and potentially in species with similar absorptive cells. Our findings highlight the potential role of VSP across species.
Long‐term conservation planning for diadromous fishes would benefit from a better understanding of both the role of connectivity among environments and habitat variability in the expression of ...life‐history diversity. Most of the scientific knowledge on habitat fragmentation and connectivity has been developed in terrestrial systems in the discipline of landscape ecology. Research on habitat connectivity in aquatic systems (e.g., salmonid research that spans the spectrum of habitats from freshwater to the sea) is uncommon and largely focused on barriers to fish passage. Here, we present a review of the literature characterizing current research patterns on habitat connectivity within and among environments for Pacific salmon. We found this topic is still incipient: the literature is dominated by studies of freshwaters, with few articles focusing on habitat needs in estuary and marine systems. Pan‐environment studies are rare, pointing to a gap in our understanding of complex habitat relationships that might be significant in the development of long‐term conservation and restoration plans for Pacific salmon, particularly in light of the potential impact of climate change.
Research Impact Statement: Science supporting Pacific salmon habitat connectivity is dominated by freshwater studies with limited marine and estuary work that is also critical for effective conservation planning.
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