Aquatic Living Resources最新文献

Snakehead (Channa lucius Cuvier, 1831) is a species of potential aquaculture interest in the Mekong Delta, Vietnam. However, their optimum environmental conditions have yet to be determined. This study aims to study the hatching success and larval and fry growth of C. lucius at six pH levels (5.5, 6.0, 6.5, 7.0, 7.5, and 8.0). Two consecutive experiments were conducted. Experiment 1 focused on incubating eggs and nursing the yolk sac larvae, and was carried out in aquariums. The monitoring included incubation time (IT), hatching rate (HR), and deformation rate of the newly hatched larvae (DR). Larvae were also collected daily during nursing for growth determination. In Experiment 2, four-day-old fry after hatching from experiment 1 were reared in plastic tanks with live feeds for 30 days. Growth was checked every ten days, while survival rate (SR) and coefficient of variation (CV) were determined at the end of the experiment. pH 5.5–8.0 was favorable for incubation, larvae, and fry, as assessed through good indicators of IT, HR, DR, and larval length and weight growths, as well as length and weight growths, SR, and CV of fry. Furthermore, the lowest DR (0.33%) was at pH 5.5, while except for pH 7.0, the shortest IT (41.1 h) significantly differed from that at higher pH levels (p < 0.05), and the highest larval growth parameters were at pH 5.5–6.0; meanwhile, pH 5.5–6.5 supported a better life for fry, as showed by the significantly higher growth parameters (p < 0.05) and SR and CV improvements in fry after 30 rearing days. Overall, pH 5.5–8.0 was suitable for the early stages of C. lucius, in which pH 5.5–6.0 was better for incubation and larval growth and pH 5.5–6.5 was better for fry development.

Redbelly tilapia (Coptodon zillii) is a member of a group of fishes in the Cichlidae family endemic to the northern half of Africa and the Middle East. In the literature, the name C. zillii is mostly associated with a negative impact on the ecosystem and biodiversity in the areas to which it was introduced. In its native range, it is not a much-appreciated fish species from both fisheries and aquaculture perspectives because of its small size and difficulty to catch when compared to Nile tilapia, Oreochromis niloticus. Although C. zillii has several desirable aquaculture traits such as feeding at lower trophic levels, high fecundity, saltwater and cold tolerance, the attempts to capitalize on this potential are lacking. Moreover, comprehensive studies that characterize its ecological niche in its native range and adaptive mechanisms of invasiveness in introduced areas are also limited. Notwithstanding, it is a species of invasion concern that requires continuous monitoring and implementation of mitigation actions in non-native regions. Compilation of information regarding the environmental requirements, feeding, and reproductive biology of C. zillii may serve as a starting ingredient for further research and management of its invasiveness, which is highly required in the face of freshwater ecosystem modifications as a result of climate change. This paper also addresses the current state and potential of C. zillii for utilization in capture fisheries and fish farming.

The fishing sector in the Adriatic Sea is exposed to stricter regulations due to the negative ecological impact of large-scale fisheries, while increasing socio-economic challenges threaten the profitability of the industry. We apply Stochastic frontier and Price formation analysis to the rapido fishery of Chioggia (Italy) in order to investigate potential strategies to enhance the economic performance of the fishery, considering both effort restrictions and market trends. The use of two different methodological approaches emphasizes the need for a comprehensive and flexible approach to fisheries management, taking into account seasonal fluctuations in efficiency and average prices. The results reveal that efficiency variations are significantly influenced by seasonal factors and stock availability, thus indicating a limited capacity of fishers to adapt to changing market conditions. We emphasize the importance of flexible scheduling of fishing days and discuss the opportunity for implementing mixed management systems incorporating a Total Allowable Catch or quotas.

Meeting the resource demand for an increasing human population has led to the emergence of the aquaculture industry as the fastest growing sector for food production worldwide. Modern finfish aquaculture has raised environmental concerns and, to address this, Integrated Multi-Trophic Aquaculture (IMTA) has gained popularity as a means to minimise environmental impacts. This is done by culturing extractive species alongside fed species to utilise excess nutrients and enhance their own growth. The current study, based within the Atlantic Area of Europe, identified suitable habitats for the three species Sparus aurata, Mytilus galloprovincialis and Ulva rigida, for use in a new IMTA system. Models were created using MaxEnt software and input into GIS software (ArcMap 10.8.1) for analysis. For all species, the AUC results in the model were >0.9, with values of 0.931 (S. aurata), 0.928 (M. galloprovincialis) and 0.939 (U. rigida), demonstrating significant predictive power. Jackknife testing of the model for each species identified the mean sea surface temperature (°C) and Chlorophyll A (mg m^–3) concentration as the two most important variables. The model showed that areas of >50% suitability could be found throughout the study area, although the most suitable sites were in coastal areas in more southern latitudes. To identify the feasibility of establishing an IMTA system in different areas, the shipping density, MPA status and the locations of harbours were added to the maps for further consideration. Using this study, and the species-specific information identified by the model, the aquaculture industry will be better equipped to identify potential IMTA sites and integrate these systems into the EU market for sustainable production.

In the context of the general overexploitation of South Pacific reef fisheries, there is a global push to precisely define fishery parameters such as fishing effort, annual landings, and exploitation levels. In Bora-Bora, several surveys were performed to define the fishing grounds and the fishing effort of the reef fishery for the first time. Maps of the fishing grounds under different fishing pressures were created for the Bora-Bora reef fishery. The average fishing effort throughout the lagoon was 40 trips week⁻¹ km⁻². Annual landings were estimated following two different methods: school participatory surveys and landing based on the catch per unit effort. These estimations were used to determine that the maximum sustainable yield of the island's fisheries was 6.5 tons km⁻² year⁻¹. the reported annual yield in 2022 was 5.35 tons km⁻² year⁻¹, under the estimated maximum sustainable yield. The level of exploitation of the fisheries was also estimated based on the catch size composition of the ten most fished species. This revealed that fishing is responsible for more than 50% of fish mortality in six of the ten studied species, and that catch length could be increased to optimize both catches and biomass. Overall, the Bora-Bora reef fishery may be experiencing growth overfishing (i.e., the catching of fish that are too small to maximise biological sustainability and economical yield), which can endanger stock recruitment in the future if no actions are taken.

Habitats of three marine fish species of major interest (Epinephelus aeneus, Pseudotolithus senegalensis, and Pagellus bellottii) at both juvenile and adult life stages were identified and mapped in the western part of the Gulf of Guinea. Habitat suitability models (HSMs) were designed to quantify species- and stage-specific fish densities from scientific survey data collected for the last 40 years according to two environmental descriptors (bathymetry, distance to river mouth) and accounting for temporal contrasts. Delta general linear models were selected to fit with the 0-inflated distribution of the fish density data. Despite their high residual deviance, both the prediction accuracy and robustness of these HSMs were satisfactory. HSMs showed a strong influence of bathymetry on stage-specific fish distribution and a lower and non systematic influence of proximity to river mouths. The spatial distribution of juveniles of E. aeneus and P. senegalensis evidenced their concentration in shallow coastal nurseries. The adults of P. senegalensis were also located in nearshore habitats under estuarine influence, whereas adults of E. aeneus were spread towards deeper waters. P. bellottii did not rely on coastal fringes at juvenile or adult stages. Finally, model outputs showed a decrease in abundance in recent decades for all species at both life stages. These HSMs and maps reveal the importance of the coastal fringe as a critical essential habitat for two of the three studied species and the usefulness of space-based management measures to maintain populations and ensure sustainable fishing exploitation.

Macrobrachium nipponense is a major farmed species freshwater shrimp in China and its genetic diversity is of high value in aquaculture. The construction of the Three Gorges Project has slowed down the water velocity in the Three Gorges Reservoir (TGR) and made the water more clear, which is more favourable for the survival and reproduction of M. nipponense. However, there are lack of studies on the genetic diversity of M. nipponense populations in the TGR. In this study, mitochondrial COI gene sequences were used as molecular marker to analyze the genetic diversity, genetic differentiation and historical demography of eight M. nipponense populations in the TGR. The results showed that the M. nipponense populations in TGR have high genetic diversity. There was some genetic differentiation between the four populations in lower reaches of the TGR and four populations in the upper reaches of the TGR. We also found that there was a significant correlation between genetic distance and geographical distance among the M. nipponense populations in the TGR. The M. nipponense population in the TGR has experienced population reduction in the recent year, which might be related to the ice age movement in the Little Ice Age and human activities. This study provides a theoretical basis for the rational development and protection of M. nipponense resources in the TGR.

The Lake Chad basin is one of the most politico-ecologically complex regions in Africa. The rapid global climate change caused by decades of unsustainable resource utilization has not only impaired the ecosystem function but has escalated further conflict with the associated terrorism in the region. This paper reviews the notion of environmental peacebuilding through the introduction of trans-boundary conservation as a mechanism to achieve peace and harmony in the Lake Chad region. The proposed trans-boundary conservation area will restore ecosystem services, conserve biodiversity, improve livelihood, and reduce poverty in the Lake Chad basin. The paper provides justification for the establishment of the “Lake Chad trans-boundary Ramsar site” as an example of how a trans-boundary conservation area could act as a catalyst for improved political cooperation using inter-linkage with other Multilateral Environmental Agreements in the region.