Aquaculture, Fish and Fisheries最新文献

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.

Relaxants are used in abalone aquaculture to facilitate handling, transport and grading stock, with minimal injury, stress, immune suppression and mortality. Benzocaine has been commonly used as an abalone relaxant but negative behavioural responses to exposure have been observed, and in some countries it has a withholding period, precluding its use for rested harvest, so alternatives are needed. We screened seven candidate relaxants (propylene phenoxetol, magnesium sulphate, magnesium chloride, tricaine methanesulphonate (MS-222), clove oil, AQUI-S and 2-phenoxyethanol) and benzocaine on small (1 year old, 18–28 mm shell length) greenlip abalone (Haliotis laevigata Donovan). We determined the effect of a range of concentrations of each product on abalone and assessed relaxation and recovery times and behavioural responses to exposure to the relaxants. The effect of exposure to these products on abalone growth was evaluated over 90 days after immersion treatment. Adverse effects on behaviour, foot colour, ease of release, relaxation and recovery time, survival or growth were seen using MgSO₄, MS-222, clove oil, AQUI-S and benzocaine. Three products (2-phenoxyethanol, propylene phenoxetol and MgCl₂) met criteria for practical use and are candidates for further investigation for use as relaxants for greenlip abalone aquaculture.

Sea cucumber ranching has been proposed as a sustainable, low-trophic source of seafood while remediating organic aquaculture waste. This exploratory study investigates the bioaccumulation and depuration of two finfish veterinary therapeutants, emamectin benzoate (EB) and oxytetracycline (OTC), in the European black sea cucumber (Holothuria forskali) within controlled conditions. Sea cucumbers (n = 80) were fed medicated aquafeed for 7 days, followed by tissue sampling at intervals up to 33 days. Mean initial tissue concentrations were 12.18 ± 0.99 ng/g for EB and 3.45 ± 2.90 µg/g for OTC. The elimination half-lives (t_1/2) were 10.7 days for EB and 23.1 days for OTC. Notably, 78% of sea cucumbers eviscerated their internal organs after exposure, and seven mortalities occurred. The sampled control animals (n = 20) were intact, indicating potential physiological stress from ingesting therapeutants. This exploratory study provides critical initial data on therapeutant impacts after ingestion by H. forskali, highlighting the need for further field validation to establish appropriate withdrawal periods for sea cucumber ranching within aquaculture systems using veterinary therapeutants.

The Nannochloropsis oceanica microalgae contain a high content of polyunsaturated fatty acids, amino acids, and proteins, which are essential in diets intended for the cultivation of mollusks, crustaceans, and fish to ensure good larval growth and better survival. Counting any microalgae is fundamental to maintaining the good health of mollusks and other species that base their diet on this organism. Currently, in different aquaponics processes, counting is done manually, which is tedious for the technician and prone to errors. This study proposes an automatic counting system based on computer vision and machine learning. We describe the development of two applications. The first one allows the technician to manually count the microalgae, marking them manually to build a microalgae dataset. Once we generated the dataset, we trained classical machine learning models and compared them against a convolutional neural network (CNN). Finally, we integrated these models into a second desktop application in which the technician selects the region of interest within the microscopy image, and the app counts the microalgae based on the previously trained models. We report 91% accuracy in the CNN-based model we trained, which is an adequate percentage given the noise and variable lighting conditions of the microalgae dataset.

Protein sparing is an established practice in feed manufacturing where relatively inexpensive ingredients, such as lipids, are incorporated to reduce or ‘spare’ expensive protein ingredients. In this 84-day study, Yellowtail Kingfish, Seriola lalandi (2.13 ± 0.23 kg, mean body mass ± SD; 504 ± 19 mm, fork length ± SD), were fed six different diets formulated on a digestible basis that contained highly palatable and digestible ingredients at realistic commercial inclusion levels to evaluate lipid digestion and storage. Diets were formulated to graded crude protein (CP) levels (40%, 44% and 48%) and either 25% or 30% crude lipid (CL). Lipid and glycogen storage were not significantly affected by CP or CL level. However, a negative relationship between increased CP and hepatocyte vacuolisation was indicated. Crude protein did not influence the bile acid concentrations in digestive tissues, whereas diets with a 30% CL level decreased the total bile acid concentration of gallbladder content compared to that of fish fed diets with a 25% CL level, but no other digestive parameters were affected. Fish fed a dietary CL level of 25% had elevated taurine concentrations in the liver compared with fish fed diets containing a 30% CL level. Liver 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) concentration of fish fed diets containing 40% CP level was reduced compared to fish fed diets containing 48% CP levels. Total bilirubin of fish fed 48% CP was less than that of fish fed 44% CP but not fish fed 40% CP, which was similar to that of fish fed both 44% CP and 48% CP. At the water temperatures recorded in this study, Yellowtail Kingfish can be fed diets with up to 30% CL and 48% CP without affecting total bile acid synthesis, storage and liver lipid storage.

In Brazil, a large quantity of shrimps captured through commercial fishing is marketed as labelled frozen packages following current legislation (Normative Instruction No. 23, of 20 August 2019). This study tested the possibility of errors in species identification (forensic analysis) listed on the labels of packages sold in the country by using mitochondrial molecular marker. Labelled samples (packages) were acquired in supermarkets in different states of Brazil, and specimens were selected on the basis of apparent morphological differences for analysis. DNA was extracted from each specimen selected from packages, with 16S marker amplification, DNA purification and sequencing. Generated sequences were compared with those available in GenBank using BLAST and grouped by neighbour-joining method. Mislabelling was detected regarding species identification. Specimens of Pleoticus muelleri (Solenoceridae) were labelled as ‘pink shrimp’, which should be some species from the genus Penaeus (Penaeidae). Furthermore, representatives of Artemesia longinaris and P. muelleri were found under the label ‘seabob shrimp’ (i.e., Xiphopenaeus spp.). On the other hand, most of the samples were in accordance with the regulations regarding species identification. Our results indicated that some packages (8.8%) do not comply with the regulations. This finding means lack of precision about what is being commercialized and suggests the necessity to propose adjustments in-line with consumer rights and species conservation.

This study evaluates the performance of an integrated aquaponic system combining gravel bed and NFT modules within a recirculating loop, focusing on nutrient dynamics, plant growth and sensory quality. Conducted in a semi-controlled greenhouse, the system utilized Nile tilapia (Oreochromis niloticus) and cultivated lettuce, Swiss chard and pepper. Water quality analysis showed reduced nitrate levels after the NFT module (0.792 mg/L) compared to source RAS water (1.04 mg/L), while the gravel bed demonstrated superior phosphate removal (0.052 mg/L) and the lowest ammonia concentration (0.074 mg/L). Lettuce grown in NFT exhibited significantly greater shoot biomass (187.00 ± 15.53 g) than gravel-grown plants (105.33 ± 11.79 g), with similar differences observed in root biomass. Plant performance was significantly influenced by the cultivation system, plant variety and their interaction. Pepper plants in NFT produced more fruits (9.00 ± 1.47 vs. 5.50 ± 0.96) and longer fruits, while gravel-grown fruits had ∼8% greater average mass, although this difference was not statistically significant. Sensory evaluation indicated a general preference for NFT-grown lettuce in appearance, aroma, texture, flavour and overall acceptability, though these differences were not statistically significant. Economically, the NFT system yielded higher returns and lower media costs, resulting in a net financial benefit of 11,804.52 ETB. Overall, the NFT system outperformed the gravel bed in plant productivity, nutrient efficiency and economic viability, while gravel beds may offer advantages in contexts requiring greater phosphate or ammonia retention.

Genetic selection for carcass traits has always presented difficulties, because it is necessary to slaughter the animals to collect direct measurements of these traits. So, we evaluate, by path analysis, the cause-and-effect relationship between morphometric measurements and carcass traits on pacu Piaractus mesopotamicus, a very important species for aquaculture in Latin America. A total of 120 fish, at different ages, were anaesthetized, measured in standard length (SL), head length (HL), body height (BH) and body width (BW), slaughtered and processed to obtain the weights and yields of carcass, head, fillet, rib and residue. Path analysis was employed to estimate direct and indirect effects, with body part weight and yields as dependent variables and morphometric measurements and relationships as explanatory variables. Body and rib weights, as well as head yield, are strongly influenced by morphometric variables; HL/BH ration and SL can be used efficiently to determine and indirectly select these traits. With less efficiency, it is possible to indirectly select animals with higher weights and fillet yields and lower residual weights using BH, BW and SL, respectively.

The cover image is based on the Original Article by Evaluation of Nutrient Flow Through and Media-Bed Aquaponic Systems by Belay Abdissa et al., https://doi.org/10.1002/aff2.70122.