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 reef octopus Octopus cyanea fishery is the most economically important fishery in southwest Madagascar. The substantial increase of octopus exploitation in the region has raised concerns over the sustainability of this fishery. While a growing number of measures have been implemented to sustainably manage the octopus stock, there is a lack of information on the status of this octopus stock. In this study, we analyse the status of octopus stock in southwest Madagascar by investigating the interannual and seasonal variability in recruitment and fishing mortality using virtual population analysis (VPA) performed on monthly basis from 2020 to 2022. Yield per recruit is also predicted using a Thomson and Bell model. Our results indicate that octopus fishery national closures (December 15 to January 31 each year) result overall in increase of catches and stock biomass, evidencing the positive impacts of the implemented fisheries regulations in the region. Recruitment exhibits high interannual and seasonal variability with a peak observed between October and December. The simulation model suggests that yield per recruit remains almost unchanged from one year to the next and not exceeding the maximum yield per recruit. Overall, this study shows the importance of understanding the status of octopus stock for sustainable octopus fisheries in southwest Madagascar.

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.

Smallmouth bass (Micropterus dolomieu) spawn on gravel and cobble in the littoral zone of lakes that may become degraded by the presence of fine sediments and decomposing organic matter. Substrate size and composition have been identified as important variables for nest site selection by male smallmouth bass. We tested whether ‘cleaning’ substrate by removing sediment with a pressure washer would increase the number of bass nests or the average total length (mm) of nesting smallmouth bass in selected areas of Big Rideau Lake, Ontario, Canada the following year using a before-after control-impact design. Treatment was not a significant predictor of nest abundance or average male length. Considering the strength of the experimental design it is reasonable to conclude that this intervention failed to enhance spawning substrate for smallmouth bass. Understanding the factors that maintain productive spawning sites for smallmouth bass is important to restoration effectiveness and determining where habitat enhancement will provide the greatest benefits.

Epiphytism commonly occurs in marine benthic macroalgae and seagrass communities under natural conditions and those of mariculture. This can greatly obstruct the cultivation of commercial seaweeds and ultimately impacts the seaweed aquaculture industry negatively. Against a background of climate change and a rapidly increasing market demand, the commercial Sargassum species is experiencing increasing challenges posed by epiphytic macroalgae. Severely reduced growth, lower quality, the emergence of diseases, and the ultimate death of the algae can lead to a commercial loss. Attempts to limit epiphytic macroalgae in aquaculture have so far been inefficient. However, epiphytic macroalgae are also rich in nutritional compounds and their relative biomass could be used as efficiently as the cultivated seaweed. As epiphytes cannot effectively be controlled by the current physical, chemical, and other methods in most cases, the perspective of comprehensive utilization could be an alternative over complete prevention and control by traditional methods. Compared to the existing strategies for controlling the growth and spread of epiphytes in seaweed aquaculture, the integrated and indiscriminate harvest and utilization of epiphytic macroalgae as fertilizer, animal food additive agents, as well as the development of biodegradable materials, might prove to be alternative valorization. However, the implementation of epiphytic macroalgae utilizations still needs to overcome the technical obstacles.

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.

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.

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.

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.

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.