Aquaculture, Fish and Fisheries最新文献

The current study assessed the impact of organic and inorganic feeding management on water quality, growth performance and plankton communities in a pond-based polyculture system over 9 months, using three treatments: Ctrl (C), organic feeding (T1) and inorganic feeding (T2). Significant differences were observed in electrical conductivity (EC) and total dissolved solids (TDS), with inorganic feeding showing the highest EC (1719.95 ± 41.05 µS/cm, p = 0.0017) and TDS (884.80 ± 4.90 mg/L, p = 0.0122), while other water parameters such as DO, pH and temperature showed no significant variation (p > 0.05). In terms of growth, grass carp in organic feeding showed the highest weight gain (1264.0 ± 5.0 g) and specific growth rate (2.31 ± 0.01%/day), significantly higher than inorganic feeding (1089.4 ± 1.6 g, p < 0.0001). The overall gross yield was also highest in organic feeding (238,506.5 ± 29,668.4 g/ha, p < 0.0001). Phytoplankton and zooplankton diversity and abundance were significantly greater in organic feeding, with total densities of 31,224.0 ± 145.0 and 16,485.0 ± 524.0 cells/mL, respectively (p < 0.001). Proximate composition revealed significant improvements in organic feeding fish for protein (e.g., grass carp: 22.19 ± 0.79%, p < 0.0001), fat, ash and moisture content. Organoleptic evaluation also favored organic feeding, showing significantly better texture (8.16 ± 0.22), flavour (8.43 ± 0.26) and overall acceptability (8.01 ± 0.20) compared to organic and inorganic feeding management (p < 0.0001). These findings suggest that organic feeding management (organic feeding) improves water quality (excluding EC and TDS), enhances fish growth, promotes richer plankton communities and improves fish nutrition.

In the past half-century, fishing in one regional part of the Baltic Sea, the Stockholm Archipelago, has almost disappeared due to falling fish abundance, especially of herring (Clupea harengus). By examining published observations and archived material on historical fishing patterns, we found evidence of a remarkably continuous high level of fish supply throughout most of the nineteenth and twentieth centuries, despite variation in fish recruitment, high abundance of mammal predators and high fishing intensities. We observe that fishing was part of a true market, i.e., fishing acted as an opportunistic predator, abandoning specific target species at low abundance and fishing on present surpluses. Our study contributes to advancing historical marine ecology and adds to critiques of explanations of declining and collapsing fisheries in terms of inevitable ‘tragedies of the commons’. Our observations of historical management approaches contrast with contemporary Swedish fisheries management and may inform a different strategy towards achieving sustainable fisheries in the Baltic Sea and elsewhere.

Astaxanthin is a potent dietary carotenoid known to enhance growth and pigmentation in fish. This study evaluated the effects of graded dietary astaxanthin supplementation, extracted from Haematococcus pluvialis (0, 25, 50, 75 and 100 mg/kg) on growth performance, feed utilisation, body colouration and survival of Nile tilapia (Oreochromis niloticus). A total of 375 fish with initial weight (4.31 ± 0.37 g) were randomly distributed into fifteen 110 L tanks in triplicate groups and reared for 60 days. Feed intake and condition factor were not significantly affected among treatments (p > 0.05). Fish fed the 75 mg/kg diet exhibited significantly higher length gain (5.15 ± 1.04 cm), weight gain (14.90 ± 0.34 g) and specific growth rate (2.51 ± 0.14%/day) compared with other groups (p < 0.05). Feed utilisation was also improved, with the lowest feed conversion ratio (1.48 ± 0.04) and highest feed conversion efficiency (0.68 ± 0.02). Survival rate was highest at 75 mg/kg (97.44 ± 1.22%) with no significant difference (p > 0.05) from 100 mg/kg. Muscle carotenoid (4.84 ± 0.14 µg/g) and astaxanthin (0.22 ± 0.01 µg/g) increased dose dependently, with the greatest pigmentation observed at 100 mg/kg. Although the highest dose improved colouration, growth was slightly reduced compared with the 75 mg/kg group. These results indicate that 75 mg/kg dietary astaxanthin optimally enhances growth, feed efficiency, pigmentation and survival in Nile tilapia, supporting its use as a functional feed additive in aquaculture.

Trial Registration: Not applicable

The West African mangrove oyster, Crassostrea tulipa, exhibits high variability in shell morphology, which is influenced by both genetic and environmental factors. The current study investigated the plasticity of C. tulipa sub-populations within the Densu Estuary, Ghana, from May 2017 to October 2018 with respect to shell morphology, as impacted by some environmental parameters. The study is aimed at providing useful information on the plasticity of oysters in the face of harsh environmental conditions with respect to shell development. The study was carried out in Stations 1, 2, 3 and 4 (a and b), where oysters were present in Stations 3, 4a and 4b. Allometric studies were carried out on oyster samples from three sub-populations within the Densu Estuary. Temperature, DO, salinity, pH and turbidity were monitored. Bulk density of sediments at the sub-populations was determined. There was no marked difference in the variations of the physico-chemical parameters between Station 3 and Station 4 oysters, except for sediment bulk density. There was evidence of high mortality and low population density of oysters at Station 3, as compared to its counterparts. The slopes of the regression of shell height against shell length/total shell weight/wet meat weight of oysters from the various sampling stations showed negative allometry. Oysters at Station 3 showed isometric growth from the regression of shell width on shell height. Station 3 oysters demonstrated higher condition indices and gonadal indices indicative of better physiological status. The findings indicated that Station 3 oysters exhibited morphometric traits consistent with enhanced reproductive potential by demonstrating phenotypic plasticity through the development of bigger inner shell volume for gonadal development and maturation at small shell size in the face of harsh environmental conditions.

This study investigates the adaptation strategy of wild Asian seabass (Lates calcarifer) to artificial feed in an open floating cage over a period of 360 days. A total of 1800 wild seabass with an initial length of 19.91 ± 0.26 cm and a weight of 72.85 ± 3.94 g was stocked at a density of 15 fish per m³ in 60 m³ cages and subjected to two feeding strategies. In Treatment 1 (T₁), fish were fed chopped tilapia (Oreochromis niloticus) across four feeding stages (S₁, S₂, S₃ and S₄). In Treatment 2 (T₂), fish were fed chopped tilapia as their primary feed in S₁, subsequently, chopped tilapia and commercial feed (45% protein) at a 1:1 ratio in S₂, followed by commercial feed in S₃ and finally formulated feed (37% protein) in S₄ at 5%–1.2% of their body weight for 90 days in each stage. The growth performance included survival rate of 94.33%, weight gain (WG) of 1035.85 ± 34.09 g, specific growth rate (SGR) of 0.76 ± 0.01% per day, feed conversion ratio (FCR) of 2.75 and feed efficiency ratio (FER) of 0.36 in T₁. In comparison, T₂ exhibited a survival rate of 92.44%, WG of 1221.54 ± 47.79 g, SGR of 0.81 ± 0.02%/day, FCR of 2.45 and FER of 0.41. Proximate composition differed significantly among feeding stages, with a higher protein percentage observed in T₂. Gut contents analysis revealed that fish predated natural food inside the cages, while intestinal morphology showed significant stage-dependent changes. Total production of seabass was 904 kg (15.07 kg/m³) in T₁ and 1050 kg (17.5 kg/m³) in T₂. The benefit-cost ratio (BCR) was 1.7 for both T₁ and T₂. Therefore, a gradual transition to formulated diets enhances growth performance and production efficiency of wild Asian seabass while maintaining economic viability in open cage aquaculture.

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.