Aquaculture, Fish and Fisheries最新文献

Nile tilapia (Oreochromis niloticus), native to Africa and the Levant, is an important species for both aquaculture and capture fisheries. Despite these attributes, Nile tilapia has been negatively impacted by anthropogenic activities ranging from overfishing and habitat destruction to translocations. These human-mediated activities have threatened the genetic evolutionary integrity of native populations of Nile tilapia and congeneric species through admixture, demographic bottlenecks and introgressive hybridization. In this context, the genetic contrast between farmed/bred strains and wild Nile tilapia populations in the major lakes of Uganda remains understudied. Understanding the genetic structure of Nile tilapia populations in the major water bodies of Uganda (lakes Victoria, Kyoga, Edward, George, Albert and Nile River) is a key resource to guide selective breeding programmes, thus minimizing the effects of maladaptation under both aquaculture and natural stocks. Although the population genetics of Nile tilapia in Uganda's major lakes have been studied, this was based on limited sampling scope, especially in the wild, and the key information on the species could have been overlooked. We fill this knowledge gap by genotyping 756 Nile tilapia individuals from multiple populations for each major water body of Uganda using a panel of 34 microsatellite loci based on the microsatellite genotyping-by-sequencing (SSR-GBS) technique. The results indicate two discrete gene pools/stocks: the Edward-George system and the Albert-Kyoga system-Victoria. Evidence of loss of genetic diversity and admixture of some Nile tilapia stocks was found, most likely resulting from anthropogenic perturbations. This study contributes useful information key for understanding the potential Nile tilapia broodstock sources for selective breeding programmes, aimed at improving aquaculture production in Uganda.

Determining the most appropriate stocking density for a specific fish species in an ambient condition is essential for successful cage aquaculture in terms of profitability which is mainly governed by growth. The current study was conducted to ascertain which stocking density gives the best result of widely cultured species in cage aquaculture, pangas (Pangasianodon hypophthalmus), at swamp forest environment of Ratargul Freshwater Swamp Forest, Bangladesh in terms of growth, production and economic return. Fish were reared for 93 days at three stocking densities, namely 30, 40 and 50 fish/m³ which were denoted as FSD30, FSD40 and FSD50, respectively, containing three replications of each. Growth and yield comparisons indicated that the stocking density of fish had significant (p < 0.05) effects on growth rate and productivity. Fish cultivated at the maximum density (FSD50) had lower mean weights than fish reared at lower densities. The significantly highest mean weights (376.58 ± 14.65 g) and benefit–cost ratio (BCR) (1.617 ± 0.035) obtained from FSD30 show the suitability of this density in terms of fish growth and profitability of pangas in swamp forest environment.

This study examined the growth patterns of the spotted catfish, Arius maculatus (Thunberg, 1792) in the Thanlwin River Estuary throughout the analysis of standard lengths obtained from observed otolith data and back-calculated data. Between April 2023 and January 2024, 516 fish ranging in standard lengths from 8.3 to 33 cm were collected. The annual deposition of annuli in otoliths was confirmed using the marginal increment ratio, with ages ranging from 2 to 9 years. The Dahl-Lea back-calculation method expanded the length at age data to 2472 records for ages 1–9 years. Growth was characterized using Von Bertalanffy growth curves, revealing the significant differences between the observed data (asymptotic length L∞ = 25.34 cm, growth coefficient K = 0.257 year−1 and growth performance index ϕ′ = 2.02) and the back-calculated data (L∞ = 36.23 cm, K = 0.087 year⁻¹ and ϕ′ = 2.21). The findings of the study suggested that the back-calculated otolith data were more dependable for determining growth parameters compared to the observed otolith data. A. maculatus appears to exhibit slow growth characteristics, suggesting that the environmental conditions in the Thanlwin River Estuary may be deficient for this species. The insights gleaned from this research are crucial for guiding and shaping fishery management policies through informed advice and recommendations.

We evaluated the utility of three male-specific molecular markers, sdY, sdY 227U and OtY2m, in two wild populations of masu salmon (Oncorhynchus masou) in southwestern Hokkaido, Japan. Male-specific fragments amplified in all phenotypic males across the markers. Phenotypic females were genetically identified as males using sdY (57%) and sdY 227U (4%), but no phenotypic females were identified as males using OtY2m. We conclude that OtY2m was the most reliable sex marker, followed closely by sdY 227U, among those tested in our study populations. Additional research is warranted to test the applicability of these markers in other populations and Oncorhynchus species.

The commercial viability of walleye (Sander vitreus) as an aquaculture species requires that walleye gametes are available year-round so that multiple cohorts of walleye can be brought to market throughout the year. This study aimed to apply photothermal manipulations to three groups of walleye broodstock to induce out-of-season spawning and obtain a year-round supply of fertilized walleye eggs. We manipulated photothermal regimes for three groups of broodstock to induce spawning in February (early), April (in-season), and July (late-season). In autumn, water temperatures were chilled to 8°C in all treatments. The duration of the chill period varied for each treatment with the early, in-season, and late treatments remaining chilled for 6, 18, and 30 weeks, respectively, before being warmed to induce spawning. Fecundity was significantly lower for late-season broodstock. Egg size and gonadosomatic index were significantly smaller in the early-season treatment. Fertilization success was similar for early and in-season treatments but was 0% for eggs from the late-season treatment. Larval survival was significantly lower for walleye from early-season broodstock. Our results suggest that early out-of-season spawning for walleye is possible but comes with tradeoffs of smaller egg size and lower larval survival.

Black sea bass (Centropristis striata; BSB) are a commercially managed species with an increasing population in the Northwest Atlantic Ocean. Understanding their movement ecology can be difficult due to their wide distribution and ability to inhabit both inshore and offshore reef habitats. BSB have been studied using a range of tagging techniques, and here we present the results of the first deployments of pop-up satellite archival tags (PSAT) on this species. During 2019 and 2021, we conducted four fishing trips within the southern Mid-Atlantic Bight region of the NW Atlantic and tagged a total of 30 fish with T-bar tags and external data loggers, of which 4 received a PSAT and the rest received a Star-Oddi conductivity–temperature–depth (CTD) archival tag. All PSATs transmitted some data, with short attachment durations (8–32 days) relative to the programmed release of 250 days, and we did not recover a Star-Oddi tag. External tag attachment techniques need to be examined and improved before continued deployment of larger data loggers on BSB.

Offshore oil and gas platforms support abundant reef fish and are popular fishing sites for recreational anglers. However, the rapid decommissioning and removal of active platforms have decreased such fishing opportunities in the Gulf of Mexico, raising concerns about fisheries impacts. Conversely, planned offshore energy structures like wind turbines may offer similar habitats and fishing sites. To inform spatial planning for marine energy infrastructure in the context of recreational fisheries, we created models of fish communities associated with oil and gas platforms using existing abundance data. We employed Random Forest analysis to predict the presence-absence and abundance of Red Snapper (Lutjanus campechanus) and Greater Amberjack (Seriola dumerili) at platforms using 47 environmental and platform variables. Nonmetric multidimensional scaling on Bray−Curtis dissimilarities explored fish species composition among 37 species. Results showed variability in Red Snapper and Greater Amberjack incidence/abundance from shore to shelf-edge, not attributed to surrounding habitat or climatological oceanographic variables. Incidence models were more robust than abundance models. Fish species composition was significantly influenced by location gradient, with less impact from other habitat features. Our findings guide selecting areas for artificial structures to enhance angler opportunities and maintain fish diversity, but identifying the drivers of finer scale abundance variation will require further sampling.

The cover image is based on the Short Communication Discovery of mineralizations in the caudal vertebrae of perch (Perca fluviatilis L.) — a potential new tool for environmental impact assessment by O. Magnus Karlsson et al., https://doi.org/10.1002/aff2.183.

Aquaculture is a key component of Ghana's food system strategies, promoting sustainable animal protein production. Aquaculture complements traditional marine capture fisheries to close the gap between demand and supply. However, about one third of fish produced globally have been reported to go to waste yearly. Among the various cultured fish, the Nile tilapia Oreochromis niloticus is a predominant species. This study aimed to estimate the extent of Nile tilapia wastage by consumers in Ghana. A web-based cross-sectional consumer survey was designed to assess the parts of the tilapia consumers generally classified as edible or inedible, taking into account the three primary tilapia preparation methods. The study utilised a semi-structured online questionnaire, gathering responses from 246 participants. The parts of Nile tilapia investigated included the flesh, fins, offal, head, scales, bones, and gill flaps/opercula. The analysis of consumed and wasted parts of Nile tilapias by weight showed that, on average, the flesh made up the majority of the fish at 55.26%, followed by the head at 26.46%, offal at 8.51%, scales at 3.10%, fins at 2.93%, bones at 2.76%, and operculum at 0.98%, which was the smallest component. The study concluded that approximately 30%–45% of waste is generated from Nile tilapia in the Ghanaian supply chain. Tilapia was widely consumed by all groups, with an average liking score of 7.69 ± 1.95 on a 10-point hedonic scale. A significant association was found between gender and consumption patterns with females showing a higher degree of liking. There was a strong association between the method of preparation and consumption patterns; the fried parts were classified as more edible compared to those that were boiled or grilled. To reduce waste in the aquaculture industry, tilapia and other fishes could be processed in a way that various edible and inedible parts are sold separately.

Using stable isotope analysis, we assessed the relative contributions of the main protein contributors fishmeal, soya and sunflower meal to mature abalone muscle and gonad tissue over 1 year. Prerequisites for the use of stable isotope mixing models were established in this species. The δ¹³C and δ¹⁵N discrimination factors and turnover rates were influenced by diet composition, and there were tissue-specific and sex-specific differences. Abalone were fed the two combination diets (fishmeal–soya and fishmeal–sunflower meal) grew at similar rates. However, feed was most efficiently utilised in abalone fed a combination of fishmeal and soya. The relative contribution of fishmeal, soya and sunflower meal to female and male abalone tissue growth fluctuated throughout the 1-year study. Overall, fishmeal contributed over 50% of the gonad (54%–82%) and muscle (54%–84%) tissue growth in females. Similarly, fishmeal contributed over 50% of gonad tissue growth of male abalone, ranging from 59% to 87%, while the contribution to meat tissue growth in males ranged from 44% to 94%. These findings support the importance of laboratory studies when using stable isotope analysis and mixing models for nutrient allocation in aquaculture.