Search Results (1,101)

Carbon stable isotopes (δ¹³C) are widely used in ecological studies to understand diet, food web dynamics, and movements of marine fishes. Still, δ¹³C is influenced by lipid content and often requires chemical extraction or mathematical correction. Here, we developed a species-specific mathematical lipid correction for white muscle tissue of yellowfin tuna (Thunnus albacares), a highly migratory finfish of considerable economic and ecological value. Lipid extraction was conducted on yellowfin tuna white muscle tissue (C:N range: 2.96–6.49), and both linear and non-linear lipid correction models for δ¹³C were fitted and assessed. Lipid extraction increased δ¹³C, and to a lesser extent, δ¹⁵N values in yellowfin tuna white muscle tissue, but had no effect on δ³⁴S. Both non-linear models provided better fits to the data than the linear model, suggesting an asymptotic relationship between C:N and ∆δ¹³C. Results support the growing body of evidence that C:N ratios can be used to predict lipid corrected δ¹³C and highlight the value of mathematical correction approaches. We provide species-specific parameter estimates that can be used for lipid correction of white muscle tissue for δ¹³C analysis in yellowfin tuna and similar species for which species-specific models have yet to be developed. Full article

The study aimed to evaluate the effect of inorganic mercury (iHg) on the sperm quality, embryos, and larvae of Prochilodus magdalenae. Two experiments were carried out. In experiment 1, semen was activated with contaminated water at different iHg concentrations (0.0, 25, 50, 100 µg/L) and sperm kinetics were analyzed with a computer-assisted semen analysis (CASA) system. In the second trial, 2 g of oocytes were fertilized with 50 µL of milt, activated with contaminated water at different iHg concentrations (0.0, 25, 50, 100 µg/L), and maintained that way during the first hour of incubation. Samples were taken every 3–4 h until hatching to identify embryo deformations. Fertilization and hatching rates were estimated. The survival of newly hatched larvae (1 day) and larvae eight days post-hatching (dph) was also assessed. The results show that the quality parameters of semen treated with contaminated water at different iHg concentrations (25, 50, 100 µg/L) were altered and showed significant differences (p < 0.05) from the control group (0 µg/L). Total motility decreased (9.8–13.2%) and the amount of immotile sperm increased (3-fold) relative to values in the control group. A significant increase in oocyte diameter and a decrease in fertilization and hatching rates were observed with the higher iHg concentrations (50–100 µg/L). Embryo deformations (>40%) such as scoliosis, lordosis, and microcephaly were observed, as well as premature hatchings. The larval survival at 1 dph was reduced between 25% (25 µg/L) and 97.2% (100 µg/L) relative to that in the control group. The results suggest that bocachico semen, embryos, and larvae are sensitive to contamination with iHg from 25 µg/L. Full article

The aquaculture production of pikeperch has reached commercial scale in a number of European countries, but the high mortality of early life cycle stages and minor understanding of nutritional requirements are still major bottlenecks. To investigate the fate of fatty acids during early development, weaning and rearing, pikeperch larvae and juveniles from a commercial recirculating aquaculture system (RAS) were sampled over 2 months for morphometric data, as well as fatty acid composition, with a total of 6 sampling days, with four to five replicates per sampling day and between 1 and 25 pikeperch larvae per individual sample, depending on larval biomass. The biomass of sampled pikeperch larvae varied from 0.1 to 420 mg (dry mass DM), depending on the age of the larvae, and the initial length of the pikeperch larvae was about 4.5 mm. Our data confirm that, accompanied by an exponential increase in dry mass, total fatty acids (TFAs) in larval tissues increased with the beginning of exogenous feed uptake and were depleted between days 13 and 25 post hatch, most likely associated with the weaning and metamorphosis of the larvae. We conclude that all fatty acid classes may serve as metabolic fuel during metamorphosis, but the ultimate fatty acid composition is strongly impacted by the available feed. The chosen diet probably caused a lack of alpha-linolenic (18:3n-3; ALA) and docosahexaenoic acid (22:6n-3; DHA) during larval development and a shortage of vaccenic (18:1n-7), alpha-linolenic (18:3n-3; ALA) and arachidonic acid (20:4n-6; ARA) in juvenile pikeperch. This led to low DHA/EPA ratios 13 days post hatch, a high EPA/ARA ratio at days 41 and 56 post hatch and a fluctuating ratio of alpha-linolenic acid to linoleic acid (18:2n-6; LA). A temporary lack of essential fatty acids can cause dysfunctions and eventually mortalities in pikeperch larvae and juveniles. Despite high larval growth rates, the biochemical composition of the first fed Artemia and microdiets was most likely not sufficient and in need of improvement. We suggest that deficiencies must be compensated, e.g., through the substitution of the offered Artemia with more suitable live feed organisms, such as freshwater rotifers, and the enrichment of current microdiets in order to prevent high mortalities during pikeperch rearing and weaning. Full article

Haliotis gigantea, a commercially cultivated abalone in China, predominantly displays the pale-yellow-footed trait. However, a limited occurrence of the orange-footed muscle trait makes it a valuable candidate for breeding programs. In our research, we examined the inheritance pattern of the orange-footed trait and conducted a 90-day feeding trial for H. gigantea to compare the influence of formulated feed and macroalgae on pigment enrichment and growth rates. Our results suggest that the orange-footed trait has a recessive nature relative to its common counterpart and demonstrates stable inheritance. We also identified a significant correlation between color-difference values (a*) and total carotenoid content (TCC) (R² = 0.955, p < 0.05), suggesting the TCC in abalone foot muscle can be estimated using the a* value. Furthermore, introducing carotenoids to formulated feed imparts an orange hue to the foot muscle, but this effect is inferior compared to using Gracilariopsis lemaneiformis with a similar carotenoid content. This suggests that H. gigantea has a higher absorption efficiency for the carotenoids from the macroalgae G. lemaneiformis compared to formulated feed. Growth assessments indicate that the formulated feed, enriched with higher crude protein than G. lemaneiformis, optimally supports H. gigantea growth. Our findings furnish valuable insights that could steer breeding strategies and feeding practices towards achieving the orange-footed muscle trait in H. gigantea. Full article

Legislation and interest exists to protect and restore freshwater and marine ecosystems from the environmental impact of aquaculture. However, aquaculture-induced eutrophication remains a major environmental concern. Water soluble phosphorus, uneaten feed, feces, and metabolic waste from farmed fish increase phosphorus concentrations in adjacent waters. In open freshwater fish farms, in particular, the effects can be more immediate, as excess phosphorus is introduced directly into ecosystems. Several intestinal enzymes, transporters, and regulating factors have been implicated in farmed fish dietary phosphorus retention. For example, alkaline phosphatase and other transporters aid in the absorption of phosphorus in the anterior intestine, while pH, calcium, and vitamin D influence these enzymes and transporters. This process may also be influenced by intestinal morphology and the gut microbiome. To reduce phosphorus pollution from open flow fish farms, a thorough understanding of the processes that affect nutrient retention and absorption, as well as the impact of dietary factors, anti-nutritional substances, and intestinal morphology, is required. Aquaculture can be made more sustainable by reducing phosphorus release. This can be achieved by optimizing feed composition, adding functional feed ingredients, managing gut health, and treating effluent aquaculture waters with bioremediation and absorbing materials. Anti-nutritional factors can be mitigated through processing and through the use of functional feed additives. Addressing these issues will reduce aquaculture’s environmental impact, ensuring aquatic ecosystem health and global food security. In addition, treating effluent aquaculture waters with bioremediation and absorbing materials can remove phosphorus from the water, preventing it from entering the environment. This can further reduce the environmental impact of aquaculture and help to ensure the sustainability of this sector. Full article

The rapid warming of the Northern hemisphere has especially challenged the evolvability of anadromous fish species, such as Atlantic salmon (Salmo salar), which must cope with drastically different environments depending on their life-history stage. We studied the long-term trends in, and the effects of environmental factors and life-history traits on, Atlantic salmon growth rates in both freshwater and in the ocean using c. 35,000 scale samples collected across 48 years from spawners returning to three tributaries of the subarctic River Teno in the northernmost parts of Finland and Norway (70° N). The freshwater growth has decreased in all three populations and spending more than three juvenile years in freshwater before the sea migration comes at the expense of growth. On the other hand, returning mature salmon (one-sea-winter, 1SW) showed increased growth at the sea with increasing marine temperatures, which results in larger sizes at return in 1SW spawners. We did not observe such trends in growth rates in larger, two-sea-winter salmon. Here, we report the contrasting responses in Atlantic salmon growth rates to a warming climate depending on the life-history stage. Full article

(1) Background: Klotho is a multifunctional protein, but its biophysiological roles during fish early development are unclear. (2) Methods: We carried out anti-sense Klotho morpholino injection and whole-mount in situ hybridization experiments in this study. (3) Results: Our results showed that in the Klotho MO1-injected group, embryos displayed longitudinal shapes and swelling yolks compared to those of the un-injected groups. Their length/width ratio by 9 hpf for the uninfected group is 1 ± 0.1; but for 0.1 mM-, 0.2 mM-, and 0.5 mM-MO-injected are 1.1 ± 0.1, 1.2 ± 0.1, and 1.3 ± 0.1, respectively, suggesting that the klotho knockdown-induced length/width ratio changes are in a dose-dependent manner. Whole-mount in situ hybridization showed that several cell migration-related gene expressions, including goosecoid, floating head, bone morphogenetic protein 4, and even-skipped-liked 1 were affected in the Klotho MO-injected embryos. (4) Conclusions: We suggest that knockdown of klotho leads to cell movement impairment during zebrafish gastrulation. Full article

Accurate recording of growth indicators for aquaculture species at different stages is essential for evaluating aquaculture production effectiveness and the rationality of feed formulations. Due to their convenience and non-invasiveness, weight, length, and condition factor are commonly used to assess the growth of aquaculture species. However, fish growth indicators, can vary significantly with age structure and feed components (nutrition), and relying on a single indicator may lead to misjudgments. In this study, we investigated the growth indicators of Gibel carp (Carassius auratus gibelio var. CAS V) at different growth stages (juvenile and adult) and different feed formulations. Meanwhile, the fish weight–length relationship ($\mathrm{W}=\mathrm{b}{\mathrm{L}}^{\mathrm{a}}$) was used to assess the growth indicators. The results showed that the weight–length relationship of Gibel carp varied significantly with age and feed formulation. Additionally, the condition factor calculated depended on the weight–length relationship being more similar with weight and length change trend than the condition factor was measured. Weight analysis indicated that weight, length, depth, body width, and carcass ratio had higher weights when analyzing fish growth. Therefore, during aquaculture production, fish growth evaluating requires considering diverse indicators such as weight, length, body depth, body width, and carcass ratio, as well as the condition factor, to avoid misjudging the actual growth situation. Meanwhile, the use of the condition factor should consider the sufficient number of data and whether the assumptions (such as being in an isometric growth period) are met. Full article

Marine fishery is an important part of China’s maritime power strategy. Improving the ecological efficiency of marine fishery is the inevitable way to achieve the sustainable development of fishery. Based on the perspective of industrial sustainable development, this study used the Super-SBM model to evaluate the ecological efficiency of marine fishery in 11 coastal provinces of China from 2011 to 2020. Combined with Malmquist index, Moran index and other methods, the spatial and temporal evolution characteristics were analyzed. On this basis, the Tobit panel model was used to explore the influencing factors of marine fishery eco-efficiency. The results show that: (1) From 2011 to 2020, the marine fishery eco-efficiency in the 10 coastal provinces and cities of China shows a clear trend of improvement, and the efficiency values in high-efficiency areas remain basically stable. The relative gap between efficient and inefficient regions remains significant. (2) From the perspective of spatial distribution characteristics, the ecological efficiency of marine fishery in coastal provinces and cities in China had no obvious spatial correlation, and showed a trend of cross-distribution between high-efficiency regions and low-efficiency regions. (3) The change of marine fishery eco-efficiency is the result of a variety of influencing factors. Fishery industrial structure, scientific and technological support levels and environmental regulation play a role in promoting the improvement of marine fishery eco-efficiency. Therefore, optimizing the structure of the fishery industry, improving environmental regulation and increasing investment in science and technology are all effective measures for local governments to improve the eco-efficiency of marine fisheries. Full article

This study investigated the effects of different protein sources and butyric acid contents in aquafeed on the growth, survival rate, lipid peroxidation enzymes, and intestinal villi of 7.3 g jade perch, Scortum barcoo. The experimental treatment groups were the whole fish meal protein (FM) group, the FM + butyric acid (FMB) group, the 50% fish meal protein and 50% black soldier fly meal protein (FBM) group, the FBM + butyric acid (FBMB) group, the whole black soldier fly meal protein (BM) group, and the BM + butyric acid (BMB) group. The experimental results showed that the jade perch fed with the FMB feed had a significantly higher weight gain rate and antioxidant enzyme activity than the other treatment groups. The red blood cell count, hemoglobin concentration, and hematocrit contents in the blood of jade perch were not affected by the protein source, but they increased with the addition of butyric acid. The intestinal villi length of the jade perch that were fed diets containing butyric acid were significantly higher than that of the jade perch that were fed diets without butyric acid supplementation. The results of this study show that the addition of butyric acid to a balanced feed composed of protein can contribute to the growth of jade perch. Full article

Studies have shown the abundance of fisheries resources in the waters of the northern part of the Philippines bordering southern Taiwan. However, discrepancies in legal frameworks, enforcement mechanisms, and cultural practices, as well as maritime boundary issues, contribute to complexities in collaboration. This paper thus aims to provide an understanding into the intricacies and challenges faced by both countries in managing their shared fishing resources. By analyzing the relevant international laws and instruments on fisheries cooperation, the paper shows what coastal states and entities fishing in the high seas could do to manage and conserve fishery resources in disputed areas. Existing fisheries agreements in the region such as the Taiwan–Japan Fisheries Cooperation provide a template of the kind of cooperation that can be concluded within the overlapping waters of both nations. Results of the analysis show how important it is for both nations to acknowledge the significance of fisheries cooperation in the overlapping waters. By recognizing the mutual benefits of sustainable resource management through peaceful dialogue, establishing a fisheries cooperation under the legal framework of the WCPFC is the logical solution. The findings contribute to understanding the complexities of cross-border fisheries cooperation and provide valuable insights for policymakers and stakeholders in the region. Full article

In the present study, we investigated the age, growth, and reproductive characteristics of Euchiloglanis davidi, a species of Sisoridae fishes, from the Yalong River, China. Fish samples were collected from the tributaries of the middle and lower Yalong River in May 2013 and December 2015. Their standard length ranged from 67 to 190 mm, and the total weight ranged from 3.42 to 75.06 g. The age and growth pattern of E. davidi were determined using the vertebra. Furthermore, the sampled fish were categorized into 10 age groups (1–10 years old): the maximum age was 10 years and 9 years for male and female fish, respectively. The relationship between the standard length and weight was expressed as W = 6.744 × 10⁻⁵ L^2.653, and the t-test showed allometric growth. The growth of E. davidi was defined by the von Bertalanffy growth function, described as L_t = 260.8(1−e^{−0.104(t+1.942)}), W_t = 173.5(1−e^{−0.104(t+1.942)})^2.653, respectively. The growth inflection point was observed at 7.44 years, with corresponding length and weight values of 162.50 mm and 49.46 g. The fecundity ranged from 105 to 352 eggs, with an average of 205 eggs. The relative fecundity of weight (F_W) ranged from 2.90 to 8.98 eggs/g, and the relative fecundity of length (F_L) ranged from 0.71 to 2.11 eggs/mm. Altogether, these characteristics of slow growth and low fecundity demonstrated the vulnerability of E. davidi to exploitation in the middle and lower reaches of the Yalong River. Full article

Between September and October 2021, a total of seven adult specimens (five females and two males) of Umbrina ronchus Valenciennes, 1843 were caught in the waters off Portopalo di Capo Passero and Porto Empedocle (the south-eastern coast of Sicily). This was the first record of this species in the Strait of Sicily and the deepest record of this species within the Mediterranean Sea. Individuals of U. ronchus ranged from 180–240 mm total length and 69–149 g total weight. Gonad stages ranged from maturing to spent/resting. Otoliths sagittae were oval shaped with high rectangular yet complex contour. Counting the growth zones by transverse section, the estimated age ranged from 3 to 5 years. Since sciaenids are considered a high-longevity species, a quite recent settlement of U. ronchus in the Strait of Sicily is suggested. As the biogeographic nature of the Strait of Sicily is the main boundary between the western basin, which is characterized by a high affinity for (sub)tropical Atlantic species such as U. ronchus, and the eastern basin, which has an affinity for the indo-pacific warm waters species, the present records could be the limit to the eastward expansion of the geographic distribution of U. ronchus in the Mediterranean Sea. Full article

The effects of diets fermented with compound probiotics, namely Lactobacillus acidophilus, Limosilactobacillus reuteri and Lactiplantibacillus plantarum, on the growth performance, physiological and biochemical indexes, fatty acid composition and intestinal health of juvenile largemouth bass (Micropterus salmoides) were investigated. Three hundred healthy juvenile M. salmoides (5.29 ± 0.02 g) were selected and randomly divided into two groups with triplicates for each. The basic diet was set as the control group (CON), and fermentation of the basic diet with a mixed bacterial solution (1.8 × 10⁹ cfu/mL, L. acidophilus:L. reuteri:L. plantarum = 1:1:1) was set as the fermentation group (FER). Fish were hand fed to satiation for 56 days and two-thirds of the culture water was renewed every 3 days. The results showed that feed intake of fish in the FER group was significantly lowered, thereby increasing feed efficiency (FE) and protein efficiency (PER) (p < 0.05). Serum alanine aminotransferase (ALT) activity was significantly decreased, and catalase (CAT) activity was significantly increased in the FER group (p < 0.05). The liver superoxide dismutase activity (SOD) was significantly enhanced, and intestinal trypsin was significantly increased in the FER group (p < 0.05). Being fed with the fermentation diet significantly increased the content of n-3 polyunsaturated fatty acids (PUFA), docosahexaenoic acid (DHA) and the n-3/n-6 PUFAs ratios in the liver (p < 0.05). Intestinal histology showed that villus height and width of the intestine and the number of goblet cells were significantly increased in the FER group (p < 0.05). Those fed with fermentation diets had limited diversity of gut microbiota. Compared to the CON group, the relative abundance of Aeromonas decreased significantly (p < 0.05), while the relative abundance of Fusobacteria, Cetobacteria and Lactobacillusis in FER increased greatly in the gut microbiota of the FER group. In conclusion, fermented feed with the three probiotics effectively improved the feed utilization and antioxidant capacity, promoted digestion and absorption of dietary protein, improved the ability of synthesize DHA and n-3 PUFAs in the liver and reduced the abundance of pathogenic bacteria in the gut. Therefore, the present research provided a new way of co-fermented feed with three probiotics for the aquaculture of M. salmoides. Full article

Microplastic (MP) pollution is a prevalent and global threat to fish. MP contamination was investigated in Harpadon nehereus collected from the principal fishing harbors of India’s northwest coast. A total of 213 specimens were collected from the major fishing harbors of Gujarat state (Jakhau, Okha, and Jaffrabad) and Maharashtra state (Mumbai). In the laboratory, the morphometric parameters of the specimens, such as total length and body weight, were measured. The collected specimens were analyzed for MP isolation using the previously documented protocol. MPs were quantified under a stereomicroscope, and physical parameters were recorded. All the examined specimens were found to be contaminated with MPs, with an abundance of 6.98 ± 6.73 MPs/g. The maximum contamination of MPs was recorded at the study site in Jaffrabad, followed by Jakhau, Mumbai, and Okha. Morphometric analysis of MPs revealed threads to be the most dominant shape. Black and blue MPs with a 1–2 mm size were the predominant recorded types. The chemical composition of extracted MPs revealed polyethylene (PE), polystyrene (PS), and polyurethane (PU) as polymer compositions. Conclusively, the findings highlighted a greater menace to seafood safety due to trophic transfer, which causes a hazardous effect on human health. Full article