Fisheries Monitoring Research Articles

Enhanced Fishing Monitoring in the Central-Eastern North Pacific Using Deep Learning with Nightly Remote Sensing

The timely and accurate monitoring of high-seas fisheries is essential for effective management. However, efforts to monitor industry fishing vessels in the central-eastern North Pacific have been hampered by frequent cloud cover and solar illumination interference. In this study, enhanced fishing extraction algorithms based on computer vision were developed and tested. The results showed that YOLO-based computer vision models effectively detected dense small fishing targets, with original YOLOv8 achieving a precision (P) of 89% and a recall (R) of 79%, while refined versions improved these metrics to 93% and 99%, respectively. Compared with traditional threshold methods, the YOLO-based enhanced models showed significantly higher accuracy. While the threshold method could identify similar trend changes, it lacked precision in detecting individual targets, especially in blurry scenarios. Using our trained computer vision model, we established a dataset of dynamic changes in fishing vessels over the past decade. This research provides an accurate and reproducible process for precise monitoring of lit fisheries in the North Pacific, leveraging the operational and near-real-time capabilities of Google Earth Engine and computer vision. The approach can also be applied to dynamic monitoring of industrial lit fishing vessels in other regions.

You only look once v8 for fish species identification

<p>This research aims to test the performance of you only look once (YOLOv8) in identifying fish species in Indonesian waters. Fish image data is obtained from various sources to conduct testing. The results show that YOLOv8 is able to identify fish species with a mAP accuracy rate of 97%. These results reveal the great potential of deep learning technology in supporting the preservation of marine biodiversity as well as the development of various applications, such as fisheries monitoring, conservation, and marine-based tourism development in Indonesia. With its efficient object detection and classification capabilities, YOLOv8 can simplify and accelerate the process of identifying fish species, even on a large scale. Thus, this technology is a highly effective solution to overcome the challenges of manual fish species identification, which requires a lot of time and effort. The results of this study provide valuable insights into the potential utilization of Indonesia's natural resources in the context of scientific development, the tourism industry, and the fisheries sector, which is vital to the country's economy.</p>

Practice of Territorial Use Rights in Fisheries in Coastal Fishery Management in China: A Case Study of the Island Reefs Fishery Lease Policy from Shengsi County in Zhejiang Province

Coastal fisheries are vital for food supply, employment, and social stability. However, overfishing is a common problem, often attributed to open access. Territorial Use Rights in Fisheries (TURFs) have gained popularity as a tool to improve the sustainability of coastal fisheries, but research on TURFs in China is limited. This paper examines the island reef fishery lease policy implemented in Shengsi County, Zhejiang Province, within the Ma’an Islands National Marine Special Reserve. The policy leases the use of island reefs to a collective, aiming to address overfishing and resource degradation by establishing fishing area boundaries and limiting the number of users and usage time. Technically, it is an application of TURFs, and it represents a shift from traditional fishing licenses to collective compliance. This experience has disrupted the existing top–down fishery governance structure and signifies a transition to a rights-based fishery management system in China. Through a comprehensive investigation and analysis of the policy’s implementation, this research identifies the factors contributing to its flaws. These include the inadequate provision of national and local government policies, insufficient support for policy implementation from fishery management authorities, and the limited involvement of fishermen’s organizations. To enhance coastal fishery management, we propose that the Chinese government should build upon existing foundations by clarifying fishing rights through central and local laws and policies. Additionally, there is a need to strengthen data monitoring of coastal fisheries, conduct multidisciplinary research to improve the allocation mechanism of fishing rights, adopt diverse fishery management approaches to enhance supervision capabilities, establish a collaborative governance mechanism, and foster coordination and cooperation between grassroots fishermen’s organizations and government departments.

Optimising fisheries monitoring for rare and protected species: A south-eastern Australian case study shows low levels of interaction with a critically endangered species

Scientific observer programs are often the only means to estimate the total number and circumstances of interactions (including the life status at the time of the interaction) between commercial fisheries and threatened, endangered and protected species (TEPS). However, without estimating the precision of predefined sampling fractions, the accuracy of estimates are often poorly understood. We present a methodology to estimate appropriate sampling fractions using historical observer data from the New South Wales (Australia) ocean trap and line fishery, and implement an on-board monitoring program to estimate contemporary rates of interactions with TEPS in the fishery to evaluate the effectiveness of management measures implemented to reduce interactions. A total of 327 fishing trips (∼61,150 hook deployments) were sampled over 31 months with a single observed interaction each with the critically endangered grey nurse shark (Carcharius taurus) and scalloped hammerhead (Sphyrna lewini) recorded along with the capture of six seabirds. Observed catches included 97 species (70 finfish, 23 elasmobranchs, 1 invertebrate and 3 birds), of which 74 and 57 species were retained and discarded, respectively. Current fishing practices, combined with declines is reported effort targeting ‘large sharks’ following management reform, spatial protection measures, and gear regulations, were found to be minimising interactions between the main fishing method and TEPS. However, regular monitoring and research may be required to continually assess the effectiveness of mitigation strategies. The logic and methodology for determining appropriate sample fractions using existing data before implementing on-board sampling is relevant to the monitoring of other commercial fisheries.

Analysis of the performance of Faster R-CNN and YOLOv8 in detecting fishing vessels and fishes in real time

This research conducts a comparative analysis of Faster R-CNN and YOLOv8 for real-time detection of fishing vessels and fish in maritime surveillance. The study underscores the significance of this investigation in advancing fisheries monitoring and object detection using deep learning. With a clear focus on comparing the performance of Faster R-CNN and YOLOv8, the research aims to elucidate their effectiveness in real-time detection, emphasizing the relevance of such capabilities in fisheries management. By conducting a thorough literature review, the study establishes the current state-of-the-art in object detection, particularly within the context of fisheries monitoring, while discussing existing methods, challenges, and limitations. The findings of this study not only shed light on the superiority of YOLOv8 in precise detection but also highlight its potential impact on maritime surveillance and the protection of marine resources.

Temporal changes in a small-scale artisanal reef fishery in Brazil: Coastal development and its impacts

Small-scale artisanal fisheries perform great economic, social, cultural, and ecological roles worldwide. For fishers in adverse scenarios, resorting to alternatives such sustainable tourism is widely proposed. In this study, we investigate the long-term sustainability (1998–2020) of a small-scale artisanal fishery in Northeast Brazil, where transformations including intense coastal development, the establishment of a marine protected area, and the expansion of tourism occurred in addition to the region’s economic growth and the global trend of technological advancements. This study aims to understand how this fishery has changed over the last two decades while investigating a range of possible threats for its survival. Results demonstrated the impacts of technological innovation on fishing practices, such as the use of spearguns and small outboard motors; an increase in opportunistic fishing associated with a growing coastal population; fading of certain traditional fishing practices that often require fishers with greater experience; a shift for a fishery made up of more opportunistic amateur fishers, as artisanal, small-scale fishers switched to other income sources such as tourism. Although there are benefits from those transformations, which include the possibility of an alternative source of income and the use of technology, fisheries traditions have been affected negatively in terms of social and cultural aspects, and traditional fishing communities are left vulnerable in the absence of national fishery monitoring programs, reliable fishing data, and institutional instability. Local initiatives and empowerment of traditional fishing communities to strengthen fisher identity and participation in fisheries policy decision-making should be strongly encouraged.

First record of the bluntnose sixgill shark Hexanchus griseus (Bonnaterre, 1788) in the Guatemalan Caribbean Sea

The Guatemalan Caribbean has a deepwater fishing area close to the shore around the Cayman Trench. This study reports the first record of the bluntnose sixgill shark (Hexanchus griseus) from this fishing area. Fishery-independent surveys using longlines at ~430-465 m depth, ~11 km northeast of El Quetzalito fishing village, were conducted in 2022 and 2023. Two bluntnose sixgill sharks were captured during these surveys. The sharks were females with total lengths of 300 and 310 cm, with morphological characteristics consistent with this species. These are the first confirmed records of bluntnose sixgill sharks in the western Caribbean Sea. Expanding coastal fisheries to deeper waters presents an emerging threat to deep-sea chondrichthyans in the region. Therefore, periodic fisheries monitoring is needed to estimate their vulnerability to fishing pressure.

Impact of COVID-19 on fisheries and aquaculture in Kyrgyzstan

COVID-19 has been a major global challenge with multi-dimensional impacts beyond health and well-being. Agricultural food chains have been impacted globally and fisheries and aquaculture value chains are not an exception. This study was undertaken to determine the immediate effects of the COVID-19 pandemic on fisheries and aquaculture in Kyrgyzstan and the coping strategies of stakeholders across the value chain to facilitate necessary transition mechanisms for ensuring sector stability and resilience. Results show that the COVID-19 pandemic resulted in closure of operations and a transition to digital and remote work. Furthermore, there were disruptions in logistics and supply chains due to restriction of movement and border closures. This has led to a loss of livelihoods and employment, loss and lowering of incomes, increased fish prices, loss of access to markets, disruption in access to fish seed and feed supply, lowering of food safety and quality standards in fish, interruptions in monitoring of fisheries and aquaculture activities and disruptions to fisheries and aquaculture education. The situation called for innovative and creative solutions to build and prevail over the adversity, including using new digital platforms to reach consumers and students. In addition, cooperation between all the stakeholders across the value chain is necessary to address the future vision and development of the Kyrgyz fisheries and aquaculture sector.

Experiences in developing empirical harvest strategies for the Indonesian tropical tuna fisheries

Harvest strategies, also referred to as management procedures, are foundational to evidence-based fisheries decision making. Together with closed-loop simulation testing, termed Management Strategy Evaluation, of potential harvest strategies, they are considered to be best practice. However, the use of these approaches is still mostly limited to a small minority of high-value, data-rich stocks in developed economies. The Indonesian tropical tuna fisheries provide a rare real-world experience where formal empirical harvest strategies were being developed for data-limited fisheries within a developing economy as an operational management tool. The Harvest Strategy Framework is a departure from a previously open-access fishery for tropical tuna in Indonesian archipelagic waters. It outlines the necessary actions to operationalize the harvest strategy, including fisheries monitoring, harvest control rules, associated management measures to meet the management objectives, and immediate actions to reduce the levels of catch as a precautionary measure until the harvest strategy is fully implemented. It was developed over a 9-year national consultative process, commencing in 2014 and culminating in the official adoption of the framework in June 2023. This paper outlines key processes and challenges encountered in stakeholder engagement and technical capacity development within the intricate governance context of Indonesia. We argue that the engagement processes have cemented a future direction towards sustainable and best practice fisheries management in Indonesia and the effective co-production process has potential to show the way for other fisheries in coastal developing states who face similar challenges in managing their national and internationally shared stocks.

Satellite nighttime remote sensing promotes the spatially refined monitoring and assessment of offshore fishery

ABSTRACT Offshore small-scale fisheries, constituting 31% of global marine captures, are crucial for the promotion of sustainable fisheries. However, current fishery monitoring, assessments, and management remain incomplete. Nighttime remote sensing provides a critical perspective for monitoring fishery activities. Thus, in this study, a dynamic threshold fishing vessel detection (DTFVD) model was developed to assess and manage the spatiotemporal variations of offshore fisheries. Results demonstrated that the DTFVD model provides superior accuracy in nighttime fishery monitoring and can successfully identify a robust seasonal bimodal distribution of the Yellow-Bohai Sea's fisheries. By analysing the impacts of climate, environmental, and policy factors, this study reveals that ocean dynamics affect the seasonal and geographic distribution of offshore nighttime fisheries by enhancing ocean mixing and ecological processes. The effects of the COVID-19 lockdowns and Chinese summer fishing moratorium on offshore fisheries were also determined by nighttime remote sensing. According to future climate warming predictions, the habitats for the recruited migratory fish population may gradually move northward and disappear under climate risks, leading to the disappearance of suitable fishing areas for nighttime fisheries. Therefore, this study suggests integrating nighttime remote sensing into offshore fishery monitoring and assessment efforts for climate-adapted fishery management strategies.

Supervision of Fishery Resources through Integrated Technology

Fisheries crimes damage ecosystems and fisheries resources in waters or sea areas. Although various efforts have been made to stop criminal acts in the fisheries sector, fisheries supervision is still carried out. Therefore, policies and implementation systems for monitoring criminal acts in the fisheries sector must be considered because the public, apart from authorized supervisory officers, can supervise fisheries. This research focuses on determining policies and implementation of supervision that uses integrated technology. The normative legal research methods used are the statutory and concept approaches. Researchers also collect data and conduct studies through qualitative analysis. Law Number 45 of 2009, concerning Amendments to Law Number 31 of 2004 concerning Fisheries, is the basis for supervision. Another law included in supervision is Law Number 1 of 2014 concerning Amendments to Law Number 27 of 2007 concerning the Management of Coastal Areas and Small Islands. According to this research analysis, integrated technology for fisheries monitoring is new and needs to be taken seriously by various legislative policies.

Regional variability in remotely sensed data with respect to the distribution of some snapper fishes (Family: Lutjanidae) between the Red Sea and the Arabian Gulf

Geographically dissimilar aquatic ecosystems from similar origin promote our comprehensive understanding of the role of abiotic factors in the distribution of biodiversity from one extreme, and they provide outstanding examples of convergent evolution in biological diversity on the other extreme. A new approach to monitoring and management of fisheries and marine ecosystems is required. Sea Surface Temperature (SST) and Chlorophyll-a (Chl-a) concentration are both crucial environmental variables that have significant impacts on marine ecosystems, particularly for fishes and overall aquatic life. These factors play important roles in shaping the health, distribution, behavior, and productivity of marine organisms. In the current study, Modis-aqua daily SST and Chl-a derived data from 2002 to 2022 were loaded into MATLAB, analyzed, and compared between the Arabian Gulf and Red Sea (Egyptian territory). Additionally, the catch of the family Lutjanidae (snapper fish) was recorded in 2002 to determine the distribution of napper fish species and compare production (based on data available from 2002 to 2022) in relation to SST and Chl-a variabilities. According to the current study, Chl-a in the Arabian Gulf showed narrow fluctuations during the winter and spring months, but higher than the Red Sea, and had a significant increase in sea surface temperature (SST) throughout the summer compared to the Red Sea. Spatial and temporal interaction between the means of Chl-a and SST was significantly different (P < 0.01). On the other hand, the results showed that different thermal stresses were experienced by the Arabian Gulf and the Red Sea, as shown by the total positive SST anomaly and by events occurring in different trends. Both the total catch of lutjanid snappers and the species identified by DNA barcoding varied significantly between the two geographical regions. The current work suggests using large-scale, fisheries-independent data to map the main gradients in marine fish community and species abundance and forecast their future distribution in connection to climate change.

Using fisheries-dependent data to investigate landings of European lobster (Homarus gammarus) within an offshore wind farm

Abstract The need for alternative strategies to assist in the monitoring and sustainable management of fisheries’ resources is becoming increasingly important. In recent years, greater utilization of fishers’ knowledge has been advocated as a potentially valuable source of data that could be applied to fisheries management issues. In the current study, we addressed this by investigating the landing per unit effort (LPUE) of European lobster (Homarus gammarus) from within an offshore wind farm using a fisheries-dependent commercial fishing logbook. The logbook was provided by a single fisherman who targeted lobsters within the wind farm between 2015 and 2022 using single pots deployed in association with individual wind turbines. Generalized linear mixed modeling was used to investigate changes in LPUE over temporal scales and as the result of the presence of scour protection at turbine locations. LPUE was found to be significantly higher at turbine locations where scour protection was present compared to those turbines where it was not. Predictions from modeling suggested LPUE was nearly 1.5× greater at turbines where scour protection was present. Significant differences in mean monthly and yearly LPUE were detected with this variation likely to reflect seasonal changes in lobster activity and the effect of introducing fishing into a previously unfished area. This work highlights the potential for fishing logbooks to be applied in fisheries management. Our results also demonstrate potential fishing opportunities arising from the development of offshore wind farms and the potential for these opportunities to be enhanced.

Prvi popis hrskavičnjača Crne Gore temeljen na kombinaciji monitoringa gospodarskog ribolova i građanske znanosti

Chondrichthyans are considered a highly threatened marine species, due both to the intense fishing pressure they have experienced in the world’s Oceans over several decades, and other threats, such as habitat loss, climate change and marine pollution. A rapid decline in their populations could trigger significant negative changes in marine ecosystems, highlighting the need for improved conservation measures. This study analyzes the current state of this group in the waters of Montenegro (in the southeastern Adriatic Sea). The first national checklist is provided here, comprising of 44 species, with information on their occurrence frequencies in Montenegrin fishery catches. The dataset used consists of 1469 records obtained from 281 field samplings conducted as part of the official monitoring of commercial fisheries (DCF-DCRF) aswell as 1222 records derived from citizen science. The latter contributed significantly in documenting a greater number of species, particularly those considered threatened or rare in the region, and/or overlooked by DCF-DCRF monitoring. The frequency of species in Montenegrin catches is described based on the percentage of their records in the total number of records originating from local fisheries. The obtained results indicate that only 16% of the species recorded in Montenegro are commonly present in country’s catches, while 66% are either rare or not observed in local fishery. The creation of the country’s first checklist might contribute to overcoming drawbacks in national legislation and protection measures, notably by reporting the presence of endangered species in national marine waters.

Fisheries data management systems inthe NW Mediterranean: from data collection to web visualization.

The European Union Data Collection Framework (DCF) states that scientific data-driven assessments are essential to achieve sustainable fisheries. To respond to the DCF call, this study introduces the information systems developed and used by Institut Català de Recerca per a la Governança del Mar (ICATMAR), the Catalan Institute of Research for the Governance of the Seas. The information systems include data from a biological monitoring, curation, processing, analysis, publication and web visualization for bottom trawl fisheries. Over the 4 years of collected data (2019-2022), the sampling program developed a dataset of over 1.1 million sampled individuals accounting for 24.6 tons of catch. The sampling data are ingested into a database through a data input website ensuring data management control and quality. The standardized metrics are automatically calculated and the data are published in the web visualizer, combined with fishing landings and Vessel Monitoring System (VMS) records. As the combination of remote sensing data with fisheries monitoring offers new approaches for ecosystem assessment, the collected fisheries data are also visualized in combination with georeferenced seabed habitats from the European Marine Observation and Data Network (EMODnet), climate and sea conditions from Copernicus Monitoring Environment Marine Service (CMEMS) on the web browser. Three public web-based products have been developed in the visualizer: geolocated bottom trawl samplings, biomass distribution per port or season and length-frequency charts per species. These information systems aim to fulfil the gaps in the scientific community, administration and civil society to access high-quality data for fisheries management, following the Findable, Accessible, Interoperable, Reusable (FAIR) principles, enabling scientific knowledge transfer. Database URL https://icatmar.github.io/VISAP/(www.icatmar.cat).

Illegal, Unreported, and Unregulated Fishing in Southeast Asia: Trends and Actors

executive summary: This essay identifies trends and actors involved in illegal, unreported, and unregulated (IUU) fishing in two of Southeast Asia's regional seascapes (the South China Sea and the Sulu-Sulawesi Seascape), explores the political and socioeconomic factors that enable IUU fishing, and offers recommendations to governments and other stakeholders. main argument IUU fishing threatens the food, ecological, and economic security of coastal communities in Southeast Asia's seascapes. The region is home to incredible marine biodiversity that supports commercially important fish stocks. However, IUU fishing, poor fisheries management, and bad governance—coupled with environmental degradation and a lack of monitoring, control, surveillance, and enforcement capacity—leave these stocks in a precarious position. The clandestine nature of IUU fishing can also attract crimes of convergence, including forced labor and trafficking of humans, arms, drugs, and wildlife. To counter IUU fishing, national governments in Southeast Asia should take steps to improve cooperation, build cohesiveness, and share data and relevant information with each other and with regional organizations. Likewise, the Association of Southeast Asian Nations and regional fisheries management organizations should take a greater leadership role to facilitate data and information sharing between Southeast Asian governments. policy implications • Cooperative and joint stock assessments in the South China Sea and the Sulu-Sulawesi Seascape by governments, scientists, NGOs, and other stakeholders, with a focus on transboundary stocks, would significantly improve the monitoring and management of fisheries. • To bridge gaps in enforcement capacity, fisheries enforcement authorities should work with nontraditional partners, including local communities and trusted nations in the Indo-Pacific, such as the U.S., Australia, Japan, and the Republic of Korea. • Southeast Asian coastal states should work together to settle remaining maritime boundary disputes they have with each other and develop a cohesive regional bloc that strengthens their collective commitment to the UN Convention on the Law of the Sea and efforts to combat IUU fishing. • National governments and law enforcement should increase their capacity and technical capabilities to stop labor and human rights abuses on the water and in seafood processing facilities by working with NGOs, survivors, and other relevant stakeholders with expertise in the field.

Spatio-temporal patterns of the multi-day fishing in the Indian Ocean off Sri Lanka, and their importance for fisheries monitoring, control and surveillance

In the present study, an attempt was made to investigate temporal and spatial patterns of multi-day fishing in the Indian Ocean off Sri Lanka to elucidate how such patterns related to fishing methods of multi-day fishing vessels targeting different pelagic fish species. In the analysis, 269,564 fishing operations from 37,349 fishing trips of multi-day fishing vessels during 2019 and 2020 were used. Based on the standardized fishing effort of the three major fishing methods (i.e., longlining, drift gillnetting and ring netting), species-wise catch per unit effort (CPUE) was determined for each fishing operation.The CPUE values of the three fishing methods were grouped for fishing locations in three major basins of the Indian Ocean, and according to three monsoonal seasons having varying influences of cyclones. Accordingly, 269,564 fishing operations were summarized into 77 datasets during the study period. The mean CPUE values (kg per fishing operation) were 257.3 for longlining, 163.3 for drift gillnetting and 1642.7 for ring netting. The patterns of the data matrix were investigated using the self-organizing map routine of the Artificial Neural Network. Accordingly, based on the occurrence of target species, data were classified into six clusters from which spatio-temporal patterns of fishing operations could be visualized. Ring netting was predominantly concentrated in the equatorial region and to a lesser extent in the Bay of Bengal region, with a temporal occurrence during all three seasons. Longline fishing was also predominant in the equatorial Indian Ocean region with the majority registered in the non-cyclone period. Most drift gillnet fishing operations were concentrated in the equatorial region and the Arabian Sea region, especially during the northern Indian Ocean cyclone period. These results would provide important pieces of information for the management of pelagic fish species through monitoring, control and surveillance (MCS) of the fishery.

Artisanal fishery with surface gillnets and megafauna strandings

Bycatch is an issue of worldwide relevance involving conflicts between conservation and fishery interests. In Brazil, this conflict has been highlighted in relation to the regulation of small-scale fishery with surface gillnets. To promote management and transformation of this conflict, we analyzed the relationship between catch unloadings from small-scale fishing with surface gillnets and strandings of marine megafauna. We used fishery monitoring data and beach monitoring data in São Paulo between 2015 and 2021, relating to Chelonia mydas, Caretta caretta, Lepidochelys olivacea, Pontoporia blainvillei and Sotalia guianensis. The analyses included (i) overview of catches unloadings from small-scale fishing with surface gillnets and strandings that resulted in the death of each of these species over the course of the year; (ii) correlation tests between those variables for the northern, central, and southern regions; and (iii) performing regression analyses for municipalities within these regions, exhibiting statistically significant positive correlations. The fisheries harvest period was found not to overlap with the stranding distribution. In correlation tests, only strandings of C. mydas in the northern and southern regions, S. guianensis in the southern region and P. blainvillei in the central region showed relationships with fishing landings. The regression analysis was significant for C. mydas and S. guianensis. At the municipal level, the results were statistically significant for C. mydas in São Sebastião, Ubatuba, Ilha Comprida and Cananéia and for S. guianensis in Cananéia. However, the regression explained a small part of the mortality and other impact factors were pointed out. Non-prohibitive management measures, participatory studies, and direct methods for evaluating the interaction between fisheries and megafauna associated with environmental factors should be implemented, along with analyses on other impacts on megafauna.

A composite fishing index to support the monitoring and sustainable management of world fisheries

Overfishing has severe social, economic, and environmental ramifications. Eliminating global overfishing is one of the United Nations’ Sustainable Development Goals (SDGs). The SDGs require effective policy and progress monitoring. However, current indicators are issue-specific and cannot be utilized to measure fisheries efficacy holistically. This study develops a comprehensive index that takes into account the inputs, outputs, and ecological implications of fisheries. These components are then merged to form a single composite fishing index that evaluates both total fishing pressure on the ecosystem and historical patterns. The global fishing intensity grew by a factor of eleven between 1950 and 2017, and geographical differences emerged. The fishing intensity of developed countries peaked in 1997 and has since fallen due to management, but developing countries’ fishing intensity has increased continuously over the whole research period, with quasi-linear growth after 1980. Africa has experienced the most rapid expansion in fishing activity and now has the highest fishing intensity. This index takes a more comprehensive and objective look at fisheries. Its worldwide spatial–temporal comparison enables the identification of similar temporal trends across countries or regions, as well as areas of uneven development and hotspot sites for targeted policy action.

Twenty years of monitoring reveal overfishing of bony fish stocks in the coastal national park Banc d’Arguin, in Mauritania

Abstract Along Africa’s western coast, many local communities rely on the ocean for their livelihood. Over the last decades, introductions of new fishing techniques along with globalizing trade have strongly changed local fishing practices. The Parc National du Banc d’Arguin (PNBA) in Mauritania had for centuries been subjected to an artisanal, low‐impact, fishery. This fishing was exclusively oriented towards migratory bony fish species, mullet (Mugil cephalus) and meagre (Argyrosomus regius). Since the 1980s, these species have been replaced by illegal catches of internationally traded elasmobranchs (sharks and rays) and by non‐migratory and relict species (resident) such as tilapias (Sarotherodon melanotheron) and catfishes (Arius sp.). To date, most monitoring and management efforts have been dedicated to evaluating changes in elasmobranch populations and less focus has been on bony fish species. Data from a fishery monitoring programme are used to analyse the trends in effort, catch and catch per unit of effort of bony fish species by fitting non‐parametric generalized additive models to capture changes in the fish community over the last 20 years. Mullet and meagre became overfished early on, and the contribution of resident species (tilapias and catfishes) increased in the catches. Together with a pattern of increased effort on the traditionally targeted species, such a change in the catch could reflect a change in the fish community. These results call for the implementation of sustainable fishing practices within PNBA. We propose the need to implement closures of fisheries during the species’ breeding periods as well as the use of biological reference points such as the size at first capture and maximum sustainable yield targets for resident species.