Fish Biomass Research Articles

Distribution and abundance of ichthyoplankton in natural al artificial reefs in Edremit Bay, Northern Aegean Sea, Türkiye

Edremit Bay is one of the important areas for small–scale fishing in the North Aegean Sea. For this reason, more detailed ichthyoplankton studies should be continued to evaluate the fish stock status of the region, calculate the adult fish biomass, and determine the spawning period, place, and time of fish species. In addition, from 2011 to 2013, artificial reefs were constructed in Edremit Bay. Regular investigation of fish eggs and larvae in the region influenced by the Edremit Bay artificial reef would provide better knowledge of the structure and function of the local ecosystem and provide a basis for monitoring the marine ecosystem in the area. The current research examined the species abundance and distribution of surface plankton samples collected in 2015 and 2016. The evaluation also included the influence of abiotic environmental factors such as temperature, pH, chlorophyll a (chl–a), salinity, depth, and dissolved oxygen. Throughout the research, 3345 eggs and 176 larvae were analyzed. 57 species of eggs and larvae were identified. Eggs were not found in the natural reef (S3) in the summer and winter of 2015, while the highest egg abundance (212.83·100 m-3) was recorded in the natural reef (S1) in the summer of 2016. Larvae were not found in the natural reefs (S2 and S3) in the summer, autumn and winter of 2015 and in the artificial reefs (S4 and S5) in the summer and autumn in 2015 while the highest larvae abundance (8.12·100 m-3) on the artificial reef (S1) in summer 2016. Although the natural reefs had the highest number of species (30 species), the artificial reefs showed the lowest species diversity (17 species).

Do community changes persist after irruptive population dynamics? A case study from an invasive species boom and bust.

Irruptive or boom-and-bust population dynamics, also known as 'outbreaks', are an important phenomenon that has been noted in biological invasions at least since Charles Elton's classic book was published in 1958. Community-level consequences of irruptive dynamics are poorly documented and invasive species provide excellent systems for their study. African Jewelfish (Rubricatochromis letourneuxi, "jewelfish") are omnivores that demonstrate opportunistic carnivory, first reported in Florida in the 1960s and in Everglades National Park (ENP) in 2000. Twelve years after invasion in ENP, jewelfish underwent a 25-fold increase in density in one year. By 2016, jewelfish represented 25-50% of fish biomass. Using a 43-year fish community dataset at two sites (1978-2021), and a 25-year dataset of fish and invertebrate communities from the same drainage (1996-2021), with additional spatial coverage, we quantified differences in fish and invertebrate communities during different phases of invasion. During jewelfish boom, abundant, native cyprinodontiform fishes decreased in density and drove changes in community structure as measured by similarity of relativized abundance. Density of two species declined by > 70%, while four declined by 50-62%. Following the jewelfish bust, some species recovered to pre-boom densities while others did not. Diversity of recovery times produced altered community structure that lagged for at least four years after the jewelfish population declined. Community structure is an index of ecological functions such as resilience, productivity, and species interaction webs; therefore, these results demonstrate that irruptive population dynamics can alter ecological functions of ecosystems mediated by community structure for years following that population's decline.

Future trends of marine fish biomass distributions from the North Sea to the Barents Sea

Climate warming is one of the facets of anthropogenic global change predicted to increase in the future, its magnitude depending on present-day decisions. The north Atlantic and Arctic Oceans are already undergoing community changes, with warmer-water species expanding northwards, and colder-water species retracting. However, the future extent and implications of these shifts remain unclear. Here, we fitted a joint species distribution model to occurrence data of 107, and biomass data of 61 marine fish species from 16,345 fishery independent trawls sampled between 2004 and 2022 in the northeast Atlantic Ocean, including the Barents Sea. We project overall increases in richness and declines in relative dominance in the community, and generalised increases in species’ ranges and biomass across three different future scenarios in 2050 and 2100. The projected decline of capelin and the practical extirpation of polar cod from the system, the two most abundant species in the Barents Sea, drove an overall reduction in fish biomass at Arctic latitudes that is not replaced by expanding species. Furthermore, our projections suggest that Arctic demersal fish will be at high risk of extinction by the end of the century if no climate refugia is available at eastern latitudes.

Complex coral reefs offer hope for management in a Marine Protected Area in Zanzibar

Management of Marine Protected Areas can be supported by a detailed understanding of ecosystem state. We assessed coral reefs within Pemba Channel Conservation Area in 2019 and evaluated changes over the previous decade. In 2019, hard coral cover ranged from 3.5 % to 58.4 % across sites, while coral recruitment was exceptionally high in places (14 recruits/m2). The highest total fish biomass was ∼ 500 kg/ha, which is low compared to forereefs elsewhere in the Western Indian Ocean. Between 2009 and 2019, benthic substrate shifted to higher soft coral and turf algae cover, and mean fish density significantly decreased. This suggests that overfishing is a major threat and some reefs will require restoration to facilitate recovery. However, Pemba's unique geomorphology might offer refuge for corals from future warming and habitat for large, endangered fishes such as groupers. This could elevate the global significance of Pemba's reefs and should motivate investment in management and conservation of these resources.

Detection differences between eDNA and mid‐water trawls are driven by fish biomass and habitat preferences

AbstractMarine scientific trawl surveys are commonly used to assess the distribution and population size of fisheries‐related species, yet the method is effort‐intensive and can be environmentally destructive. Sequencing environmental DNA (eDNA) from water samples can reveal the presence of organisms in a community without capturing them; however, we expect the detectability of taxa to differ between eDNA and trawl surveys, and understanding how species traits and population variables contribute to detection differences can help calibrate our expectations from each form of sampling. Here, we coupled eDNA metabarcoding and capture trawl surveys in British Columbia, Canada, to examine species traits that explain recurrent differences in detectability between the two methods, including habitat, body size, and biomass. At the regional scale, 17 of 23 fish species (74%) captured by the trawl were detected by eDNA metabarcoding, and 39 additional species were detected by eDNA sampling only. We found that eDNA metabarcoding disproportionately detected trawl‐caught species with greater local biomass (i.e., greater biomass in the adjacent trawl). Fish detected only in eDNA had a greater range of body lengths and a broader range of habitat preferences outside the trawls' target size and sampling areas. Our results suggest that with our level of sampling, eDNA metabarcoding can adequately recapitulate detection of fish communities detected by trawl surveys, but with a bias toward fish of high population biomass and greater inclusion of fish from outside the trawled area.

Spatial-temporal patterns of fish trophic guilds in a freshwater river wetland ecosystem of northeastern China.

Muling River, situated amidst cultivated lands in Heilongjiang Province, northeastern China, has long been subjected to sand-digging activities, resulting in severe damage to its riverbed. However, little research has been conducted on the impact of this disturbance on the status of fish community structure and trophic guilds in this river. In this study, environmental factors, fish community structure, and fish trophic guild biomass distribution patterns from the Muling River basin were investigated among seasons (spring, summer, and autumn) and sections (upper, middle, and lower stream) in 2015 and 2017. During the six sampling times periods, 46 species of five orders and 12 families of fish were classified into seven trophic guilds. Fish species number and biomass were higher upper reaches of the watershed. The insectivores (16.26%), phytoplanktivores (10.09%), benthivores (40.17%), and omnivores (11.86%) were the dominant trophic guilds. We found that fish trophic guilds biomass and environmental factors such as transparency, water depth, pH value, total phosphorus, and chemical oxygen demand were highest in the upper section compared to other sections. Variation partitioning revealed that fish trophic guilds biomass was influenced more by environmental factors (61.2%), followed by section (0.7%) and season (0.1%). Partial RDA ordination showed that fish trophic guilds were positively correlated with water depth and transparency, while negative with turbidity. This study underscores the importance of considering trophic guilds of freshwater fishes to inform management strategies in regions experiencing significant environmental change.

Kelimpahan dan Biomassa Ikan Karang di Kawasan Konservasi Perairan Gili Balu, Kabupaten Sumbawa, Nusa Tenggara Barat

The Gili Balu Marine Conservation Area (KKP), located in Sumbawa Regency, West Nusa Tenggara, is ecologically and economically significant due to its rich coral reef ecosystems. This research aims to measure the abundance and biomass of reef fish in the KKP Gili Balu, which can be used as a basis for evaluating the effectiveness of conservation efforts in maintaining marine biodiversity. The Underwater Visual Census (UVC) method was used, recording types of reef fish at ten observation points. The results showed that the highest abundance was found on Mandiki Island, with functional fish abundance reaching 2973 ind/ha, followed by Pasareang Barat Island (1903 ind/ha) and South Kalong (1600 ind/ha). The biomass of functional fish also reflects their important role in maintaining the balance of the coral reef ecosystem. This research contributes to the scientific understanding of marine biodiversity in the KKP Gili Balu and provides a basis for sustainable conservation management efforts. Additionally, the research recorded the presence of several coralivorous and economically important fish species, although they tend to be smaller compared to functional fish. Economically important fish in the KKP Gili Balu waters were found only at four observation locations: East Belang Island, North Belang, Kenawa, and Southwest Namo. The highest value was recorded at Kenawa Island, with 93 ind/ha. These fish tend to be rare in this area, possibly due to past fishing practices.

Valorization of fish processing by-products for protein hydrolysate recovery: Opportunities, challenges and regulatory issues

Protein-rich fish processing by-products, often called rest raw materials (RRM), account for approximately 60% of the total fish biomass. However, a considerable amount of these RRM is utilized for low-value products such as fish meal and silage. A promising and valuable approach for maximizing the utilization of RRM involves the extraction of bioactive fish protein hydrolysate (FPH). This review assesses and compares different hydrolyzation methods to produce FPH. Furthermore, the review highlights the purification strategy, nutritional compositions, and bioactive properties of FPH. Finally, it concludes by outlining the application of FPH in food products together with various safety and regulatory issues related to the commercialization of FPH as a protein ingredient in food. This review paves the way for future applications by highlighting efficient biotechnological methods for valorizing RRM into FPH and addressing safety concerns, enabling the widespread utilization of FPH as a valuable and sustainable source of protein.

Large shallow lake response to anthropogenic stressors and climate change: Missing macroinvertebrate recovery after oligotrophication (Lake Balaton, East-Central Europe)

East-Central Europe's largest shallow lake, Balaton, experienced strong eutrophication in the 1970–80s, followed by water quality improvement and oligotrophication by 2010 CE. Recently however, repeated cyanobacterial blooms occurred and warned that internal P-recycling can act similarly to external P load, therefore we need a better understanding of past water level (WL) and trophic changes in the lake. In this study we discuss the last 500-yr trophic, WL and habitat changes of the lake using paleoecological (chironomids, pollen) and geochemical (sediment chlorophyll, TOC, TS, TN, C/H ratio, major and trace element) methods. We demonstrate that the most intensive and irreversible change in the macroinvertebrate fauna occurred during the period of economic boom between the First and Second World War (∼1925–1940 CE), when large-scale built-in and leisure use of the lake has intensified. At that time, the Procladius-Microchironomus-Stempellina dominated community transformed to Procladius-Chironomus plumosus-type-Microchironomus community that coincided with land use changes, intensified erosion and water-level regulation in the lake with the maintenance of year-round high WL. This was followed by the impoverishment and population size decrease of the chironomid fauna and Procladius dominance since 1940 CE, without any recovery after 1994 CE despite the ongoing oligotrophication. Accelerated rate of change and turnover of the fauna was connected to an increase in the benthivorous fish biomass and eutrophication. The basin lost almost completely its once characteristic Stempellina species between 1927 and 1940 CE due to trophic level increase and seasonal anoxia in the Szemes Basin. Reference conditions for ecosystem improvement were assigned to 1740–1900 CE. We conclude that in spite of the ongoing oligotrophication, the re-establishment of the Procladius-Microchironomus-Stempellina assemblage is hampered, and requires fish population regulation.

Quantitative composition of fish biomass in Qandil River Estuary and the neighboring areas

Quantitative composition of fish biomass in Qandil River Estuary and the neighboring areas

Non-Invasive Fish Biometrics for Enhancing Precision and Understanding of Aquaculture Farming through Statistical Morphology Analysis and Machine Learning.

Aquaculture requires precise non-invasive methods for biomass estimation. This research validates a novel computer vision methodology that uses a signature function-based feature extraction algorithm combining statistical morphological analysis of the size and shape of fish and machine learning to improve the accuracy of biomass estimation in fishponds and is specifically applied to tilapia (Oreochromis niloticus). These features that are automatically extracted from images are put to the test against previously manually extracted features by comparing the results when applied to three common machine learning methods under two different lighting conditions. The dataset for this analysis encompasses 129 tilapia samples. The results give promising outcomes since the multilayer perceptron model shows robust performance, consistently demonstrating superior accuracy across different features and lighting conditions. The interpretable nature of the model, rooted in the statistical features of the signature function, could provide insights into the morphological and allometric changes at different developmental stages. A comparative analysis against existing literature underscores the competitiveness of the proposed methodology, pointing to advancements in precision, interpretability, and species versatility. This research contributes significantly to the field, accelerating the quest for non-invasive fish biometrics that can be generalized across various aquaculture species in different stages of development. In combination with detection, tracking, and posture recognition, deep learning methodologies such as the one provided in the latest studies could generate a powerful method for real-time fish morphology development, biomass estimation, and welfare monitoring, which are crucial for the effective management of fish farms.

Island restoration to rebuild seabird populations and amplify coral reef functioning.

Mobile organisms like seabirds can provide important nutrient flows between ecosystems, but this connectivity has been interrupted by the degradation of island ecosystems. Island restoration (via invasive species eradications and the restoration of native vegetation) can reestablish seabird populations and their nutrient transfers between their foraging areas, breeding colonies, and adjacent nearshore habitats. Its diverse benefits are making island restoration increasingly common and scalable to larger islands and whole archipelagos. We identified the factors that influence breeding seabird abundances throughout the Chagos Archipelago in the Indian Ocean and conducted predictive modeling to estimate the abundances of seabirds that the archipelago could support under invasive predator eradication and native vegetation restoration scenarios. We explored whether the prey base exists to support restored seabird populations across the archipelago, calculated the nitrogen that restored populations of seabirds might produce via their guano, and modeled the cascading conservation gains that island restoration could provide. Restoration was predicted to increase breeding pairs of seabirds to over 280,000, and prey was predicted to be ample to support the revived seabird populations. Restored nutrient fluxes were predicted to result in increases in coral growth rates, reef fish biomasses, and parrotfish grazing and bioerosion rates. Given these potential cross-ecosystem benefits, our results support island restoration as a conservation priority that could enhance resilience to climatic change effects, such as sea-level rise and coral bleaching. We encourage the incorporation of our estimates of cross-ecosystem benefits in prioritization exercises for island restoration.

Reef health assessment of Pulau Payar Marine Park during the COVID-19 pandemic in Malaysia

Pulau Payar Marine Park (PPMP) consists of four islands, namely Pulau Payar, Pulau Kaca, Pulau Lembu and Pulau Segantang. This study was carried out in PPMP from June 2020 to February 2021, during the implementation of Malaysia’s Movement Control Order in response to the Covid-19 pandemic in the country. The purpose of this study was to determine the species, coverage and biomass of corals and fish present within the area and to assess its coral health status. Data were derived at 11 sites at depths of 5 to 10 m. The Point Intersect Line method was applied to record benthic communities for every meter across two 50-meter transect lines. The outcomes showed that benthic communities were dominated by scleractinian corals, with an average of 25% coverage at all islands. Pulau Payar, Pulau Kaca, Pulau Lembu and Pulau Segantang were characterized by 37%, 33%, 25% and 37% live coral cover respectively. A total of 14 families, 30 genera and 49 species of scleractinian coral species were identified, giving the latest comprehensive species list for this marine park. The most common species recorded was Porites lutea, followed by Physogyra lichtensteini. The fish survey revealed a total of 39 fish species from 23 genera, encompassing 16 families, with Lutjanidae being the dominant group. Fish biomass values varied between 20 g/m2 and 183 g/m2 at each site. Shannon-Wiener diversity (H), Evenness (E) and coral health index (CHI) were calculated for each island. The H values ranged between 2.03 and 3.01. Pulau Payar had the highest value of H, at 3.01, and the highest number of species. The E values ranged from 0.75 to 0.85, showing that the scleractinian corals of PPMP were relatively evenly distributed. CHI at each site ranged from 0.17 to 0.24. Overall, the health condition of the coral reefs in PPMP was considered degraded. This study provides valuable insights into the benthic and fish communities of PPMP through its health assessment.

Contribution of invasive carp (Cyprinus carpio) to fish biomass in rivers of the Murray–Darling Basin, Australia

Following the introduction of the ‘Boolarra’ strain to Australia in the mid 1960’s, Common carp (Cyprinus carpio) rapidly spread in waterways across the Murray–Darling Basin (MDB) in southern-eastern Australia. A previous study of the population expansion based upon data up to the early 2000s suggested the carp population may have reached, and was fluctuating around, the ecosystem carrying capacity. It has been widely stated in the scientific literature and media that carp comprise up to 90% of fish biomass in MDB rivers; however, this figure is largely based on sparse data collected in the 1990s and the accuracy of this estimate is uncertain. Here, we analyse three decades (1994–2023) of electrofishing data to estimate the median proportion of total fish biomass contributed by carp across > 1,400 sites in lowland rivers (< 700 m elevation) of the New South Wales (NSW) portion of the MDB. The proportion of sites with fish biomass dominated (> 90%) by carp has declined from ≈ 33% of sites in the mid-1990s to ≈ 20% of sites. The proportion of biomass comprised by carp varied depending on the scale of analysis. Across the NSW MDB, carp accounted for a median of 57% (95% CI: 42.5–70.4) of fish biomass at the site level. At the river catchment scale estimates ranged from ≈ 45–66%. In contrast, the median proportion of carp within key rivers ranged from ≈ 46–80%, suggesting that carp can dominate total fish biomass in some rivers for short time-periods. The proportion of biomass contributed by carp at the NSW MDB scale was remarkably stable across decades, suggesting that the carrying capacity of carp may have been reached. Our revised estimates of the contribution of carp to overall fish biomass can facilitate informed debate around the dominance of carp in MDB rivers and provide important information for carp management in the future.

Innovative Solution for Invasive Species and Water Pollution: Hydrochar Synthesis from Pleco Fish Biomass

In recent years, the invasive pleco fish has emerged as a global concern due to its adverse effects on ecosystems and economic activities, particularly in various water bodies in Mexico. This study introduces an innovative solution, employing microwave-assisted hydrothermal carbonization (MHTC) to synthesize hydrochar from pleco fish biomass. The research aimed to optimize synthesis conditions to enhance hydrochar yield, calorific value, and adsorption capacities for fluoride and cadmium in water. MHTC, characterized by low energy consumption, high reaction rates, and a simple design, was employed as a thermochemical process for hydrochar production. Key findings revealed that through response surface analysis, the study identified the optimal synthesis conditions for hydrochar production, maximizing yield and adsorption capacities while minimizing energy consumption. Physicochemical characterization demonstrated that hydrochars derived from pleco fish biomass exhibited mesoporous structures with fragmented surfaces, resembling hydroxyapatite, a major component of bone. Hydrochars derived from pleco fish biomass exhibited promising adsorption capacities for fluoride and cadmium in water, with hydrochar from Exp. 1 (90 min, 160 °C) showing the highest adsorption capacity for fluoride (4.16 mg/g), while Exp. 5 (90 min, 180 °C) demonstrated superior adsorption capacity for cadmium (98.5 mg/g). Furthermore, the utilization of pleco fish biomass for hydrochar production not only offers an eco-friendly disposal method for invasive species but also addresses fluoride and cadmium contamination issues, contributing to sustainable waste management and water treatment solutions. The resulting hydrochar, rich in solid fuel content with low pollutant emissions, presents a promising approach for waste management and carbon sequestration. Moreover, the optimized synthesis conditions pave the way for sustainable applications in energy production, addressing critical environmental and public health concerns. This research provides valuable insights into the potential of microwave-assisted hydrothermal carbonization for transforming invasive species into valuable resources, thereby mitigating environmental challenges and promoting sustainable development.

A novel automated approach for fish biomass estimation in turbid environments through deep learning, object detection, and regression

Estimating fish biomass is crucial in the fisheries sector, where traditional methods often harm fish through manual sampling and anesthetics. A non-invasive approach is introduced using underwater films to estimate fish biomass in turbid conditions. This study presents the “Aquatic WeightNet” dataset, targeting the Genetically Improved Formed Tilapia (GIFT) Tilapia species, and addresses the challenge of unclear images with preprocessing techniques like dehazing and Contrast Limited Adaptive Histogram Equalization (CLAHE). YOLOv8, a leading object detection model modified to accommodate the custom Aquatic WeightNet dataset's varied image sizes with five detection heads, P2 to P6, is employed, achieving a recall of 0.997 and a mean Average Precision (mAP) of 0.899 within the 50–95% Intersection over Union (IoU) range. Fish biomass estimation assesses depth, length, and width using regression models for calculation. A three-phase grid search identifies the most effective models, with the Extra Trees Regressor outperforming depth estimation with mean absolute error (MAE) of 0.63 and coefficient of determination (R2) of 0.87 and the Random Forest Regressor for length and width (MAE of 0.01 and R2 of 0.99). For biomass estimation, the Extra Trees Regressor again performs well (MAE of 0.004 and R2 of 0.99), which is critical for determining optimal feed quantities to enhance aquaculture efficiency. This study emphasizes a non-invasive method to estimate fish biomass, optimizing the effectiveness and ecological sustainability of fish farming in murky waters through advanced detection algorithms and robust regression models.

Characterizing prey fields in humpback whale foraging areas of southern British Columbia

Humpback whales ( Megaptera novaeangliae) use southern British Columbia waters to feed, but the type and quantity of prey in many areas used for feeding is unknown. We conducted active acoustic prey mapping in 55 small grid-surveys in two regions off Vancouver Island. We quantitatively compared fish and zooplankton-dominated biomass in known feeding areas with and without foraging humpback whales, and qualitatively described the prey characteristics of the foraged areas. Surveys of the water column suggest that, on average, humpback whale foraging was associated more with increased zooplankton than fish biomass. Prey characteristics varied between the two regions (∼500 km apart), but there was no significant difference in mean backscatter strength in the actively foraged areas between the two regions. Frequency differencing discriminated between the dominant taxa in the water column, but potential epipelagic prey (&lt;10 m) would have been omitted from analysis. However, average depth at the maximum acoustic prey detections was significantly deeper when whales were present (84 m) versus absent (60 m), suggesting predominantly subsurface foraging opportunities suitable to prey mapping.

Recovery potential of fish and coral populations following ecological disturbance

AbstractThe health of coral reef benthic and fish communities is implicitly connected, yet typically studied and managed separately. By developing a coupled reef population model that connects coral populations and reef fish biomass through the habitat complexity that corals build and fish live among, we aim to address this gap by holistically quantifying ecological feedbacks and responses to ecological stressors. We explored the impacts of fishing effort in conjunction with three types of ecological disturbances as they propagated through a coral reef ecosystem: (1) a disturbance that disproportionately affected small, bio‐energetically vulnerable colonies, (2) a disturbance that predominantly affected large, mechanically vulnerable colonies, and (3) a disturbance that affected colonies of all sizes randomly. We found that joint coral and fish population recovery was fastest and most complete under events affecting small colonies, followed by recovery from disturbances affecting random sizes, and lastly large‐colony disturbances. These results suggest that the retention versus loss of large coral colonies with high reproductive potential critically influenced population recovery. Low fishing levels maintained fish and coral populations and allowed for recovery after disturbances, whereas high fishing levels prevented recovery due to greater fish‐dependent coral mortality. Finally, we tested various formulations of the relationship between coral size and habitat complexity (i.e., exponential, linear, logarithmic) that constrain fish carrying capacity. All formulations led to similar population projections in most disturbance scenarios, but there were exceptions where the timing and trajectory of recovery differed, such as faster and greater recovery potential when complexity is logarithmic with respect to coral size. These findings suggest that fishing and habitat complexity mediate the recovery of coral reef populations, emphasizing the importance of describing linkages between coral size distribution and reef habitat structure. Furthermore, our results highlight the utility of the coupled‐model framework for understanding and managing the impact of disturbances at ecosystem scales.

Drivers of nutrient intakes from fisheries in French Polynesia

ABSTRACT Small-scale fisheries provide nutrients to hundreds of millions of people worldwide, with yields dependent on the condition of marine habitats such as coral reefs. Small-scale fisheries are a particularly important food source in societies with nutrient deficiencies and where unhealthy food alternatives are widely available. Using data from coral reef surveys around two islands in French Polynesia (Moorea and Raiatea), we show how the availability of nutrients to fisheries changed in relation to the condition of coral habitat. Fish biomass and nutrient availability were highest when coral cover was low around both islands, driven predominantly by abundant herbivorous reef fish. We also investigated the importance of fish in people’s diets, to determine if fish consumption was aligned with available fisheries resources on local reefs and if nutrient intakes from fish could be explained by people’s socioeconomic background. People ate a higher diversity of reef fish in Raiatea, however nutrient intakes from fish were higher in Moorea. Most people ate more fish than meat on both islands, however fish consumption declined over generations. People from fishing households had higher nutrient intakes from reef and pelagic fish, and people from farming households had higher intakes from reef fish. Preference for eating reef fish over pelagic fish was also associated with higher total nutrient intakes. Promoting traditional diets rich in fish could be key to meeting people’s nutritional needs in French Polynesia while reducing diet-related health issues linked to the overconsumption of fat. French and Tahitian versions of the are available in Supplementary Material.

Evaluating the unexplored recreational fishing in the Turkish Black Sea: socio-economic significance and environmental impact

Marine recreational fishing, a globally popular outdoor activity, has deep cultural roots and ecological implications. This study, conducted between 2021-2022, explores marine recreational fishing practices along the Turkish Black Sea coast. It analyzes fisher numbers and demographics, fishing effort, fishing methods, and species caught and released. Furthermore, the research sheds light on the economic dimensions, emphasizing the substantial contributions of recreational fishing to local economies. Notably, responsible practices, such as catch-and-release initiatives, demonstrate anglers’ awareness of conservation efforts. Within the Turkish Black Sea region, an observed 18.5% participation rate among a population of 24.5 million implies the presence of approximately 4.5 million marine recreational fishers. Annually, this translates to nearly 30 million fishing days, accompanied by a total expenditure of 400 million Euros. However, it’s imperative to handle these figures cautiously as the timing of the screening survey during the COVID-19 pandemic may have influenced the high participation rate, introducing a potential bias. A detailed examination of a Turkish marine recreational fisher engaged in Black Sea fishing reveals an average annual catch of 16.5 kg of retained fish and 1.2 kg of released fish biomass. When extrapolated to the larger population of 4.5 million fishers, this culminates in a noteworthy landing biomass approaching 74,000 tons. The study unveils that marine recreational fishers in the Turkish Black Sea predominantly target commercially important species, resulting in a retained biomass surpassing commercial landings in 2021. This prompts concerns about potential impacts on crucial commercial fish stocks, underscoring the imperative inclusion of recreational fisheries in stock assessments. The research, providing essential insights into the intricate dynamics of recreational fishing, lays a foundation for well-informed policies and practices that concurrently promote environmental conservation and the continuation of this valued leisure activity.