Aquaculture, Fish and Fisheries最新文献

This study analysed the effects of pond-management treatments on the diet composition and niche overlap of fish species by period of the production cycle in a polyculture system of pikeperch, common carp, roach and tench. Between stocking (February) and harvest (October), the treatments consisted of (i) dividing a pond in half with a net fence, stocking adult fish in one half and removing the fence (July) (‘divided’ treatment) or (ii) keeping a pond open (‘open’ treatment). Each treatment was replicated in three ponds. Fish and food resources were sampled each period, and their stable isotopes were analysed using mixing models to estimate fish diet compositions. The biomass of food resources did not differ between the two treatments, nor between the halves of the divided ponds with or without adult fish. The specific growth rate and net fish yield of each fish species also did not differ between the two treatments. Between the two treatments, the diet compositions of fish species did not differ, but they did differ between July and October, likely due to the presence of tadpoles in July. The niche of pikeperch did not overlap with those of the omnivorous fish species, as pikeperch are carnivorous. Niches of the omnivorous fish species did overlap somewhat, but less so in the divided pond, likely due to resource specialisation, but this overlap was not reflected in the diet compositions, possibly due to the low fish stocking biomass. Thus, using a divided pond design helps decrease niche competition, which may increase fish productivity.

Cultivation of eastern oysters using aquaculture gear increases habitat for temperate reef fish. Cunner (Tautogolabrus adspersus), scup (Stenotomus chrysops) and tautog (Tautoga onitis) inhabit a variety of complex natural and manmade habitats, including oyster aquaculture cage farms. Underwater video was recorded on two cage farms and a rock reef during May–September 2018 to quantify fish behavioural interactions and to assess ecological services provided by aquaculture gear, relative to natural structured seafloor. To collect video, action cameras were mounted on four study cages at a high-density farm of 40–100 commercial cages (dense farm), on four single cages interspersed on low relief seafloor (sparse farm) and adjacent to four boulders on a rock reef (rock reef), within an embayment off Milford, Connecticut in Long Island Sound (NW Atlantic). Video was recorded hourly in 8-min segments from 7 AM to 7 PM. Behaviours associated with habitat provisioning (e.g., courtship/reproduction, escape from predators, foraging, sheltering, schooling/grouping, territoriality) were observed for all three fish species on cages and boulders. Foraging and sheltering activity in cunner was significantly higher on cages than boulders while territorial behaviour occurred more frequently on boulders. Instances of escape from predators, foraging and sheltering behaviours in scup and tautog were significantly higher on cages than on boulders. Courtship/reproduction, grouping and territoriality were also higher on cages than boulders in tautog. Our results suggest that oyster cages confer ecological services that fulfil the basic biological and functional requirements of reef-oriented fish, and provide habitat attributes afforded by natural rock reefs.

Climate change significantly impacts aquaculture by altering key water-quality parameters such as temperature, dissolved oxygen, pH, ammonia, and turbidity—factors essential for effective brood fish management and seed production. This review critically examines how these environmental changes affect broodstock physiology, spawning performance, and larval development. Drawing on a wide range of peer-reviewed literature and regional case studies, it identifies integrated mitigation strategies, including optimised breeding protocols, water-quality regulation, and recirculating aquaculture systems (RAS), that can enhance climate resilience. As hatchery resilience represents a core component of broader climate resilience within aquaculture, the strategies discussed contribute to strengthening both. While these approaches show promising outcomes in addressing climate- and water-related challenges, concerns remain, in some cases, regarding their economic feasibility and long-term sustainability. The findings highlight the importance of system-based solutions that combine technological innovation, adaptive management, and multi-stakeholder collaboration. Emphasis is also placed on the need for location-specific interventions tailored to geographic and climatic contexts. The review concludes with practical recommendations to improve hatchery resilience through targeted research, supportive policy measures, and scalable, sustainable practices.

This study focuses on inducing spawning in the vulnerable fish species Esomus danricus using pituitary gland (PG) extract. Both male and female fish received intramuscular pituitary gland injections in a 1:1 ratio. Female fish were administered doses of 4 (T₁), 6 (T₂), and 8 mg kg⁻¹ (T₃), while male fish received a consistent dose of 2 mg kg⁻¹ across all treatments. Within 3–4 h of injection, the fish exhibited courtship behaviour. The average spawning rates, expressed as mean ± standard deviation, were 27.33% ± 1.77%, 49.43% ± 2.31%, and 77.67% ± 4.87% in April; 35.63% ± 2.85%, 60.67% ± 4.11%, and 87.33% ± 5.87% in May; and 37.69% ± 3.40%, 65.52% ± 4.55%, and 95.67% ± 6.09% in June for T₁, T₂, and T₃, respectively. The latency period for spawning was observed to be 6–9 h across all treatments. The highest fertilisation rate was recorded in June at 93.53% ± 6.12% for T₃, while the lowest was in April at 53.67% ± 4.60% for T₁. Similarly, the highest hatching rate was detected in June at 91.27% ± 5.78% for T₃, and the lowest in April at 30.33% ± 3.91% for T₁. Hatching occurred within 20–24 h for all treatments, and post-yolk sac absorption was noted within 60–72 h. This study successfully standardised breeding doses, offering promising prospects for the conservation and propagation of the native small fish species, Esomus danricus.

Rhein has been demonstrated to exhibit antiviral activity against nervous necrosis virus (NNV). As rhein coexists in plants with various structurally analogous natural derivatives and may acquire improved biochemical properties through chemical modification, this study investigated the potential of several natural and synthetic derivatives for anti-NNV applications. The results revealed that multiple derivatives inhibited NNV replication in infected SSN-1 cell lines more effectively than rhein. Notably, derivative 8 exhibited an IC₅₀ of 15.2 µM, whereas that of rhein exceeded 25 µM. However, in vivo experiments indicated high susceptibility of zebrafish larvae and grouper juveniles to anthraquinones, as rhubarb extract and almost all their derivatives caused nearly 100% mortality at 25 µM. Therefore, the direct use of plant extracts containing anthraquinones is not advised for juvenile fish treatment in aquaculture. In addition, an infection model using infectious tissue homogenate was established to simulate natural transmission. Immersion treatment with 10 µM rhein, a novel administration approach, effectively reduced viral load by 76.56% and improved the survival rate of grouper juveniles from 0% to 41.8%. These findings support the potential of rhein for NNV control in aquaculture practices. Although chemical modification represents a promising strategy for enhancing anti-NNV efficacy, further structural optimization is necessary to reduce toxicity.

Fishing communities in sub-Saharan Africa (SSA) face elevated HIV vulnerability, driven by occupational mobility, socio-economic marginalisation and gendered power dynamics. This qualitative review synthesises empirical studies and theoretical frameworks to examine how mobility, risky behaviours and health outcomes intersect in these communities. An integrated theoretical approach employs the push-pull model (PPM), social control theory (SCT), health belief model (HBM) and theory of gender and power (TGP). The PPM elucidates the ecological and economic drivers of fishers’ seasonal mobility; the SCT examines how transient settings weaken social bonds, enabling risky behaviours; the HBM assesses perceptions of HIV risk and barriers to prevention; and the TGP highlights how gendered labour divisions and power imbalances amplify vulnerability. Findings reveal that mobility disrupts social cohesion, fosters transactional sexual networks and increases behaviours like unprotected sex and substance abuse. The gendered roles, where men are primarily engaged in fishing and women in processing, exacerbate HIV risk due to economic dependency and sexual exploitation. This synthesis advocates for multi-level, context-specific interventions addressing structural inequalities, risk awareness and gender equity to enhance health outcomes and sustainable livelihoods in SSA fishing communities.

This study assessed the growth performance and feed utilisation of Asian seabass (Lates calcarifer) cultured under three salinity regimes (5–6, 8–10 and 2–4 ppt) in pilot-scale earthen ponds in coastal Bangladesh. Fish were stocked at 60 per decimal and fed commercial pellets throughout the trial over 254 days, with water quality consistently monitored. Data were analysed using one-way analysis of variance (ANOVA) with post hoc Games–Howell test. Significant differences (p < 0.05) were observed among salinity treatments in final body weight (BW), weight gain (WG), length gain, specific growth rate (SGR) and daily WG. Fish at moderate salinity (5–6 ppt) showed the highest growth (final BW: 840.02 ± 1.30 g; SGR: 2.16% ± 0.01% per day). Feed utilisation metrics were also superior at 5–6 ppt, including the lowest feed conversion ratio (1.27 ± 0.002), highest feed efficiency ratio (0.79 ± 0.001) and protein efficiency ratio (1.96 ± 0.003). Survival was greatest at 5–6 ppt (85.11% ± 0.15%) than in lower and higher salinity regimes. These findings indicate that maintaining moderate salinity (≈5–6 ppt) optimises growth, feed utilisation and survival in L. calcarifer, providing practical guidance for Asian seabass aquaculture in Bangladesh.

Grouper iridovirus (GIV) is a large DNA virus belonging to the family Iridoviridae and genus Ranavirus. It consists of 139,793 base pairs (bp) and 120 open reading frames (ORFs). GIV is a key pathogen of farmed fish worldwide. The functional roles of viral genes must be determined for the early diagnosis, treatment and prevention of viral infections. This study explored the characteristics of GIV-5L during viral infection. Sequence analysis of GIV-5L was performed using the National Center for Biotechnology Information (NCBI) database, leading to preliminary speculation that GIV-5L is a viral protein unique to Ranavirus. GIV-5L recombinant protein was used to immunize mice to obtain polyclonal antibodies against GIV-5L. The expression characteristics of the GIV-5L gene were then analysed. Gene expression time was analysed using cycloheximide (CHX) and cytosine arabinoside (AraC) during the infection of grouper kidney (GK) cells with GIV. GIV-5L expression was inhibited by CHX and AraC, confirming their role as late genes. Immunofluorescence staining confirmed GIV-5L expression in the cytoplasm at 12-hours post-infection (hpi) and in the nucleus at 24 hpi. This study demonstrated the functional characteristics of the GIV-5L gene, which could provide insights into GIV assembly and facilitate GIV diagnosis.

The spatiotemporal distribution of marine organisms in Taiwan is influenced by the convergence of three major water masses and the East Asian monsoon system. However, most studies on marine fish communities have focused on larval stages due to sampling limitations. To address this gap, we applied environmental DNA (eDNA) metabarcoding to assess fish diversity across three spatial scales and four seasons and to identify environmental drivers shaping these patterns. In 2023, a year-long eDNA survey at 24 offshore sites detected 1026 marine fish taxa. The results revealed strong spatial and seasonal variation in community composition, closely tied to regional oceanography. In Eastern Taiwan, fish assemblages were mainly influenced by the Kuroshio Current, with distinct patterns in the northeast likely shaped by upwelling. In Western Taiwan, seasonal changes in northern communities reflected alternating dominance of water masses from the South China Sea and China coastal shelf, whereas southern communities remained relatively stable under the combined influence of the South China Sea Surface Current and a Kuroshio Branch. These findings advance our understanding of offshore fish biodiversity dynamics in Taiwan and highlight the role of oceanographic processes in shaping community structures, offering critical insights for long-term monitoring and marine ecosystem management.

This study evaluated the production performance and profitability of an integrated multi-trophic aquaculture (IMTA) system by incorporating Indian major carp (Labeo rohita), small indigenous fish species (SIS) (Amblypharyngodon mola), snails (Pila globosa) and the floating vegetable water spinach (Ipomoea aquatica) into traditional freshwater prawn (Macrobrachium rosenbergii) ponds. Fifteen earthen ponds of 60 m² were randomly allocated to five treatments: T₁ - prawn and rohu (finfish), T₂ - prawn, rohu and mola, T₃ - prawn, rohu, mola and snail, T₄ - prawn, rohu, mola, snail and water spinach. A control was maintained, stocked exclusively with prawns. The stocking densities of the species were 2, 0.1, 2 and 0.25 m⁻² for prawns, rohu, mola and snails, respectively. In addition, 20 water-spinach sprouts were planted in a floating bed of 0.14 m². The culture period of the experiment was 7 months. The average weight throughout the experiment, final weight, weight gain and gross production of prawns were significantly higher in T₄ compared to the control group (p < 0.05). A similar level of gross prawn production was observed in T₃, which also showed significantly higher survival and gross production of rohu compared to the other groups. In addition, the production of water-spinach and snails made a surplus profit to T₄. The gross return, net profit and benefit cost ratio was significantly higher in T₄, followed by T₃ and T₂, compared to T₁ and control. The introduction of water spinach significantly reduced the concentrations of ammonia (0.02 ± 0.01mgL⁻¹), nitrite (0.05 ± 0.03mgL⁻¹), nitrate (0.27 ± 0.01mgL⁻¹), phosphate (0.03 ± 0.00mgL⁻¹) and free CO₂ (7.52 ± 5.25) in pond water compared to other groups. This reduction is attributed to the biological purification of organic and inorganic waste, enhancing the overall utilization of the trophic layers. Therefore, the application of IMTA is crucial for sustainable prawn farming to ensure food and nutritional safety.