Aquaculture, Fish and Fisheries最新文献

Efficient bait management and deployment strategies are essential for improving the sustainability of artisanal crab pot fisheries. This study investigated the effects of bait type, bait quantity and depth on the catch, size and bycatch composition of marine crabs in the crab pot fisheries in the Visayan Sea, Philippines. Field experiments utilized five bait treatments (salted fish, fresh fish, chicken intestines, crab shell and no bait), comparative tests of 40 versus 20 g bait quantities and depth sampling using 20 g salted fish baits from 1 to 21 m. Salted fish significantly increased the catch and size of Portunus pelagicus and provided an effective alternative to fresh fish in areas with limited refrigeration. Chicken intestines attracted higher bycatch. Catch and size of P. pelagicus increased with depth, while Thalamita sima tended to be smaller in deeper waters. Integrating bait optimization, pot modifications and spatial deployment based on depth can enhance species and size selectivity, reduce bycatch and limit the capture of undersized crabs, thereby supporting more sustainable and ecologically responsible artisanal crabbing operations.

Understanding the life history traits of ecologically and economically important fish species is critical for effective management. This study provides the first detailed analysis of age, growth, diet and reproductive characteristics of African pompano (Alectis ciliaris) from the southeastern United States, expanding upon prior work from the Western Arabian Gulf. A total of 54 specimens were collected off the coasts of Georgia and South Carolina when they were available during the 2024 fishing season (May–October). Age was determined via otolith sectioning, and growth was modelled using the von Bertalanffy growth function (L∞ = 96.61 cm, K = 0.689, t0 = 0.01). Diet composition was assessed using stomach content analysis, and reproductive status was evaluated through gonadosomatic index (GSI) calculations. Results indicate that A. ciliaris in this region exhibit rapid growth and early maturity, with all specimens sexually mature and the oldest fish aged at nine years. Growth comparisons suggest regional differences, with fish from the southeastern U.S. potentially growing faster than those from the Arabian Gulf. Diet analysis revealed a strong preference for cephalopods, particularly squid, which comprised over 80% of prey items. Seasonal GSI patterns suggest peak reproductive activity occurs between June and August. These findings support the hypothesis that A. ciliaris in the southeastern U.S. are migratory, arriving from Florida waters to spawn and feed during summer months. This research contributes essential data toward the life history understanding of A. ciliaris and provides valuable insights for future fisheries management and conservation efforts for this largely unmanaged species.

Essential oils are composed of secondary metabolites derived from medicinal plants and have bioactive properties, such as antiparasitic activity. This study investigated the in vitro anti-dactylogyridean efficacy of the Zingiber officinale, Curcuma longa and Cymbopogon nardus essential oils, as well as the acute toxicity for Colossoma macropomum (tambaqui). The majority chemical components of the essential oils of Z. officinale (α-zingiberene, β-sesquiphellandrene, limonene and geranial), C. longa (ar-turmerone, α-turmerone, α-phellandrene, curlone and 1,8-cineole) and C. nardus (geraniol, geranial and neral) were analysed. All the essential oils exhibited dose-dependent efficacy against dactylogyrideans Anacanthorus spathulatus, Notozothecium janauachensis and Mymarothecium boegeri, and the mean effective concentration (EC₅₀) was 16.6 mg L⁻¹ (3 h and 30 min) for Z. officinale essential oil, 30.9 mg L⁻¹ (2 h and 15 min) for C. longa essential oil and 13.7 mg L⁻¹ (30 min) for C. nardus essential oil. Effects of these oils on the ultrastructure of Anacanthorus dactylogyrideans exposed to the essential oils were also evaluated using scanning electron microscopy. This study shows for the first time the potential use of the Z. officinale, C. longa and C. nardus essential oils in controlling dactylogyridean parasites.

Mandarin fish (Siniperca chuatsi) is a high-value economic freshwater fish in China; however, the frequent occurrence of diseases threatens its production. To this end, we explored the impact of a nematode parasite newly found in the abdomen of mandarin fish collected from Pudong, Shanghai, China. This study was focused on two dimensions: (1) to use molecular biology methods to identify the taxonomic position of the nematode while also observing its morphological characteristics and (2) to assess the impact of nematode parasitism on the immune system of mandarin fish. This nematode exhibits a pink body colour and primarily resides in the swim bladder (an average 8–10 nematodes per fish). Additionally, 1–3 nematodes were observed in the abdomen, liver and peritoneum, while none were detected in the digestive tract. Initial molecular identification using universal nematode primers successfully amplified a specific band (378 bp), and BLASTn analysis revealed that the sequence showed a high similarity (99.20%) to Eustrongylides ignotus (OQ885489.1) and Eustrongylides sp. (MN066569.1, PP236907.1). The nematode was categorized under the genus Eustrongylides. In the second-round identification, specific ITS primers for Eustrongylides produced an amplification of 845 bp, which matched (100%) the sequence of MK340917.1 (E. ignotus). Therefore, we identified the nematode as E. ignotus. The trunk of the nematode is uniform in thickness, while the head and tail taper gradually. The head features several spiny papillae and papillary structures. The nematodes caused cellular vacuolation, nuclear displacement and inflammatory responses in the liver. The expressions of IL-1β, IL-8, TNF-α and NF-ĸB were up-regulated in the liver of infected fish, with the NF-ĸB displaying the most significant increase (484.37-fold). Only TNF-α was detected as significantly up-regulated in the swim bladder. This study provided essential data for molecular identification and diagnosis of nematode infections and offers initial insights into the immune response of mandarin fish.

Supplementing diets with vitamins C and E has been reported to reduce the negative effects of stress associated with higher stocking density. This study investigated the combined effects of dietary vitamins C and E on the growth, nutritional composition, haematobiochemical response and mucosal health of Nile tilapia, Oreochromis niloticus. Juvenile Nile tilapia, with an initial weight of 2.53 ± 0.02 g and length of 37.2 ± 0.7 mm, were randomly distributed into nine tanks having a higher stocking density of 30 individuals per tank (50 L water capacity). The fish were fed for 56 days with three experimental diets: CTR (vitamin C: 0 mg/kg, vitamin E: 0 mg/kg), VC200E100 (vitamin C: 200 mg/kg, vitamin E: 100 mg/kg) and VC400E200 (vitamin C: 400 mg/kg, vitamin E: 200 mg/kg). Fish fed the VC400E200 diet showed significantly higher final body weight, weight gain, percentage weight gain, specific growth rate, protein efficiency ratio, survival and condition factor, along with a lower feed conversion ratio compared to the CTR group. Fish administered VC400E200 also exhibited significantly elevated haematobiochemical parameters, particularly haemoglobin, red blood cells, packed cell volume, mean corpuscular volume and mean corpuscular haemoglobin compared to the CTR (p < 0.05). Erythrocytic cellular and nuclear abnormalities significantly decreased with the enhancement of vitamins C and E. Fish treated with dietary VC400E200 displayed improved gill and gut morphology when compared to the CTR. Principal component analysis (PCA) and Pearson's correlation demonstrated a positive correlation between condition factor and ‘PC1 intestinal and gill health’ and ‘PC1 blood variables’ of VC400E200 fed fish when compared to the CTR. The findings of this study recommend the supplementation of vitamins C and E in feed to enhance growth, feed utilization and overall health improvement in Nile tilapia.

Stinging catfish (Heteropneustes fossilis) is a commercially important farmed freshwater species in Bangladesh; however, due to various challenges in natural reproduction, hatchery-based seed supply is crucial. This longitudinal study (2022–2024) in an earthen pond assessed its reproductive performance through the gonadosomatic index (GSI), analysed its relationship with water quality and climatic variables and forecasted GSI trends using a seasonal autoregressive integrated moving average (SARIMA) model. Data from sampled female and male fish revealed clear sexual dimorphism, with female GSI peaking at 26.17 ± 0.11 during spawning in June compared to males at 1.54 ± 0.004 in July. Analysis of variance (ANOVA) revealed significant differences (p < 0.05) in gonad weight and GSI across prespawning, spawning and postspawning periods. Female GSI exhibited strong positive correlations with water temperature, air temperature and rainfall, aligning reproductive peaks with monsoon conditions (April–September). SARIMA forecasts, based on 31 months of data, predicted a gradual decline in GSI for 2024–2025, with values in June 2025 projected at 22.89, reflecting a downward trend from 26.17 in 2022. The SARIMA model demonstrated robust accuracy, capturing seasonal patterns and residual stationarity. These findings reveal the vulnerability of H. fossilis to climate change and the need for adaptive seed production and farming strategies.

Shrimp trawling contributes to seafood supply for coastal communities, but it also captures high amounts of non-target species (i.e., bycatch), which are often discarded. While one solution to address problematic bycatch is to ban trawling, the consequence may be severe on seafood security (i.e., availability and affordability), particularly in places where alternatives to local seafood are limited. Here, we underscore this trade-off by examining the controversial Kuwait's shrimp-trawling fishery, which is causing serious concerns because of its excessive amount of bycatch. Yet, far less attention is directed towards the contribution of shrimp trawling to seafood security. To help create a more nuanced understanding, we analyse available evidence on the impacts of shrimp trawling—namely, discard rates and composition of bycatch—as well as its contribution to Kuwait's seafood. We show that the total annual discard rate in Kuwait is ∼80%; shrimp trawling is responsible for an average of 55%, while other major contributors are gillnets (21%) and lines (11%). The total discarded bycatch from shrimp trawling mostly comprises species that can be categorised as juveniles of low economic value. On the other hand, shrimps are the most important species in terms of landing amount and landed value (both up to 30%). Trawling plays an important role in Kuwait's seafood security, particularly given three main aspects: (i) negligible aquaculture production; (ii) precipitous declines in some of the main local fish stocks; and (iii) increasing dependency on fish imports. Finally, we discuss the consequences of a trawling ban and highlight gear modification as a simple, implementable and customizable solution to help support Kuwait's seafood security with less bycatch.

The carpsuckers (Carpiodes spp.) are a little-studied genus of three medium-sized (0.5–3 kg at maturity) freshwater fishes within Catostomidae. These three species are widespread and common in some larger rivers in central North America, as well as some larger lakes and reservoirs. The lapillus otoliths of 189 carpsuckers (117 quillbacks [Carpiodes cyprinus], 44 highfin carpsuckers [Carpiodes velifer], 23 river carpsuckers [Carpiodes carpio] and 5 intergrades) were aged, all collected from the same Lower Wisconsin River community in 2023 and 2024 during Wisconsin Department of Natural Resources fish surveys. Age scores were precise among readers (mean coefficient of variation = 4.7%). Growth in size of each species was best modelled by von Bertalanffy growth functions accounting for sexual dimorphism, and the first comparative assessment of all three species’ growth profiles was provided. These results showed that each species exhibited highly variable recruitment across time, with most individuals from year classes produced in 2005 or earlier. Maximum ages greater than 50 years for each of the three species were observed: highfin carpsucker (56 years), quillback (51 years) and river carpsucker (56 years), as well as a maximum age of 44 years among the small sample of intergrades, making Carpiodes the second genus of freshwater fish for which three or more species have been shown to live more than 50 years. A maximum age of 56 years for the highfin carpsucker is more than six times greater than previously reported and, based on available knowledge, represents the longest lived, smallest bodied (L_∞ < 40 cm total length [TL]) freshwater fish by more than 25 years. Carpsuckers are long-lived periodic strategists living in increasingly human-altered ecosystems, as is the case for many catostomids.

Gazami (Portunus trituberculatus) is a key species in stock enhancement programs in Japan. Recently, a severe decline in the Western Japan population has been observed, emphasizing the need for improvements in these programs. This study aimed to evaluate the effects of temperature on Gazami crablets under hatchery conditions, focusing on ecdysis frequency, inter-ecdysis period (IEP), feeding behaviour and growth responses, to provide additional insights prior to their release into fishing grounds. Controlled rearing experiments were conducted in June 2023 and June 2024, under various temperature regimes. Crablets were reared in 100-L tanks at 18°C, 22°C, 26°C, 30°C and 34°C, with a control group maintained at ambient temperatures (average: 19.79 ± 0.63°C in 2023 and 21.50 ± 0.73°C in 2024). Salinity was kept at approximately 33 ppt across all setups. The 26°C and 30°C treatments significantly improved growth performance compared to ambient and lower-temperature treatments. The shortest IEP was observed at 30°C, positively influencing crablet rearing. However, at 34°C, ecdysis frequency significantly decreased, leading to slower growth and reduced food intake. These findings suggest that 30°C is optimal for enhancing ecdysis, feeding and growth in hatchery-reared crablets. However, disparities between laboratory conditions and natural temperature variations should be considered when releasing juveniles into the wild. Understanding temperature's effects on Gazami crablets can help refine conservation and management strategies to support population recovery.