Showing papers on "Fishing published in 2022"

A Global Overview of Aquaculture Food Production with a Focus on the Activity’s Development in Transitional Systems—The Case Study of a South European Country (Portugal)

Abstract: World aquaculture food production rises every year, amounting, by 2018, to another all-time record of 82.1 million tonnes of farmed seafood, with Asia leading global production. In Europe, although coastal countries present historical fishing habits, aquaculture is in true expansion. Norway, the leading European producer, is the eighth main producer worldwide. Portugal is a traditional fishing country but has invested in the development of aquaculture for the past decade, attaining, by 2018, 13.3 tonnes produced, making Portugal the 16th main producer amongst European Union member states that year. Most Portuguese aquaculture facilities operate in coastal systems, resorting to extensive and semi-intensive rearing techniques. In Portugal, marine food production in transitional systems is particularly interesting as the practice has, worldwide, been continuously substituted by intensive methods. In fact, facilities in transitional systems have developed over time and products gained higher commercial value. Clams and oysters corresponded, together, to over three quarters of total mollusc production in Portugal in 2018, while gilthead seabream and European seabass made up nearly all fish production in coastal environments. The state of aquaculture practices worldwide is reviewed in the present work, providing a particular focus on Portugal, where considerable development of the aquaculture sector is expected.

Trade-offs between bycatch and target catches in static versus dynamic fishery closures

Abstract: Significance The incidental catch of threatened species is still one of the main barriers to fisheries sustainability. What would happen if we closed 30% of the ocean to fishing with the goal of reducing bycatch? Analyzing 15 different fisheries around the globe, we found that under static area management, such as classic no-take marine area closures, observed bycatch could be reduced by 16%. However, under dynamic ocean management based on observed bycatch and closing the same total area but fragmented in smaller areas that can move year to year, that reduction can increase up to 57% at minimal or no loss of target catch. While there have been recent improvements in reducing bycatch in many fisheries, bycatch remains a threat for numerous species around the globe. Static spatial and temporal closures are used in many places as a tool to reduce bycatch. However, their effectiveness in achieving this goal is uncertain, particularly for highly mobile species. We evaluated evidence for the effects of temporal, static, and dynamic area closures on the bycatch and target catch of 15 fisheries around the world. Assuming perfect knowledge of where the catch and bycatch occurs and a closure of 30% of the fishing area, we found that dynamic area closures could reduce bycatch by an average of 57% without sacrificing catch of target species, compared to 16% reductions in bycatch achievable by static closures. The degree of bycatch reduction achievable for a certain quantity of target catch was related to the correlation in space and time between target and bycatch species. If the correlation was high, it was harder to find an area to reduce bycatch without sacrificing catch of target species. If the goal of spatial closures is to reduce bycatch, our results suggest that dynamic management provides substantially better outcomes than classic static marine area closures. The use of dynamic ocean management might be difficult to implement and enforce in many regions. Nevertheless, dynamic approaches will be increasingly valuable as climate change drives species and fisheries into new habitats or extended ranges, altering species-fishery interactions and underscoring the need for more responsive and flexible regulatory mechanisms.

Computer Vision and Deep Learning for Fish Classification in Underwater Habitats: A Survey

Abstract: Marine scientists use remote underwater video recording to survey fish species in their natural habitats. This helps them understand and predict how fish respond to climate change, habitat degradation, and fishing pressure. This information is essential for developing sustainable fisheries for human consumption, and for preserving the environment. However, the enormous volume of collected videos makes extracting useful information a daunting and time-consuming task for a human. A promising method to address this problem is the cutting-edge Deep Learning (DL) technology.DL can help marine scientists parse large volumes of video promptly and efficiently, unlocking niche information that cannot be obtained using conventional manual monitoring methods. In this paper, we provide an overview of the key concepts of DL, while presenting a survey of literature on fish habitat monitoring with a focus on underwater fish classification. We also discuss the main challenges faced when developing DL for underwater image processing and propose approaches to address them. Finally, we provide insights into the marine habitat monitoring research domain and shed light on what the future of DL for underwater image processing may hold. This paper aims to inform a wide range of readers from marine scientists who would like to apply DL in their research to computer scientists who would like to survey state-of-the-art DL-based underwater fish habitat monitoring literature.

Smaller fish species in a warm and oxygen-poor Humboldt Current system

Abstract: Description Species shifts Our anthropogenically warmed climate will lead to a suite of organismal changes. To predict how some of these may occur, we can look to past warm (interglacial) periods. Salvatteci et al. used this approach and looked at a marine sediment record of the Humboldt Current system off the coast of Peru (see the Perspective by Yasuhara and Deutsch). They found that previous warm periods were dominated by small, goby-like fishes, whereas this ecosystem currently is dominated by anchovy-like fishes. Such a shift is not only relevant to ecosystem shifts but also to fisheries because anchovies are heavily fished as a food source and gobies are much less palatable than anchovies. —SNV Fish vertebrae from marine sediments off Peru suggest a shift to smaller species in a warmer world. Climate change is expected to result in smaller fish size, but the influence of fishing has made it difficult to substantiate the theorized link between size and ocean warming and deoxygenation. We reconstructed the fish community and oceanographic conditions of the most recent global warm period (last interglacial; 130 to 116 thousand years before present) by using sediments from the northern Humboldt Current system off the coast of Peru, a hotspot of small pelagic fish productivity. In contrast to the present-day anchovy-dominated state, the last interglacial was characterized by considerably smaller (mesopelagic and goby-like) fishes and very low anchovy abundance. These small fish species are more difficult to harvest and are less palatable than anchovies, indicating that our rapidly warming world poses a threat to the global fish supply.

Rapid evolution in salmon life history induced by direct and indirect effects of fishing

Abstract: Understanding the drivers of evolution is a fundamental aim in biology. However, identifying the evolutionary impacts of human activities is challenging because of a lack of temporal data and limited knowledge of the genetic basis of most traits. Here, we identify the drivers of evolution toward maturity at an earlier age in Atlantic salmon through two types of fisheries-induced evolution acting in opposing directions: an indirect effect linked with harvest of a salmon prey species (capelin) at sea (selection against late maturation) and a direct effect due to net fishing in rivers (selection against early maturation). Because capelin are harvested as an aquaculture feed protein source, we hereby determine an indirect path by which salmon aquaculture may influence wild salmon populations. Description Pressure from both sides It is now well established that human activities impose selection that leads to evolutionary change in wild species. Some of the best examples of this process are from harvested species, especially fishes, and we know that large-scale fishing has led to effects such as early maturation and changes in adult size. Czorlich et al. looked at native populations of Atlantic salmon and found that even indigenous fishing pressure has led to evolutionary change in these populations (see the Perspective by Therkildsen and Pinsky). They also identified an additional indirect source of selection: harvest of salmon prey species at sea. —SNV Evolution toward an earlier age at maturity in wild salmon has been induced indirectly by prey harvest and directly by a size-selective harvest.

Industrialised fishing nations largely contribute to floating plastic pollution in the North Pacific subtropical gyre

Abstract: Abstract The subtropical oceanic gyre in the North Pacific Ocean is currently covered with tens of thousands of tonnes of floating plastic debris, dispersed over millions of square kilometres. A large fraction is composed of fishing nets and ropes while the rest is mostly composed of hard plastic objects and fragments, sometimes carrying evidence on their origin. In 2019, an oceanographic mission conducted in the area, retrieved over 6000 hard plastic debris items > 5 cm. The debris was later sorted, counted, weighed, and analysed for evidence of origin and age. Our results, complemented with numerical model simulations and findings from a previous oceanographic mission, revealed that a majority of the floating material stems from fishing activities. While recent assessments for plastic inputs into the ocean point to coastal developing economies and rivers as major contributors into oceanic plastic pollution, here we show that most floating plastics in the North Pacific subtropical gyre can be traced back to five industrialised fishing nations, highlighting the important role the fishing industry plays in the solution to this global issue.

Global collision-risk hotspots of marine traffic and the world’s largest fish, the whale shark

Abstract: Significance Global vessel traffic is increasing alongside world economic growth. The potential for rising lethal ship strikes on endangered species of marine megafauna, such as the plankton-feeding whale shark, remains poorly understood since areas of highest overlap are seldom determined across an entire species range. Here we show how satellite tracking whale sharks and large vessel movements globally provides a means to localize high-overlap areas and to determine how collision risk changes in time. Our results point to potential high levels of undetected or unreported ship strikes, which may explain why whale shark populations continue to decline despite protection and low fishing-induced mortality. Collision mitigations in high-collision-risk areas appear necessary to help conserve this iconic species.

Impacts of Fishing Vessels on the Heavy Metal Contamination in Sediments: A Case Study of Qianzhen Fishing Port in Southern Taiwan

Abstract: Routine maintenance of fishing vessels and wastewater discharges are primary sources of heavy metals in fishing ports. Sediment pollution assessment is necessary in fishing port management, including sediment dredging and disposal, sewage treatment facility construction, and pollution source control. In this study, sediment heavy metal contents in Qianzhen Fishing Port, the largest pelagic fishery port in Taiwan, were investigated to assess the contamination levels and related potential ecological risks using multiple sediment pollution indices. Normalization methods were applied to identify the potential sources of heavy metals in fishing port sediments. Results showed that Cu, Zn, Pb, and Cr contents in the sediments of the inner fishing port (averages of 276, 742, 113, and 221 mg/kg, respectively) were 3–5 times greater compared to those along the port entrance and outside, indicating the strong impacts of anthropogenic pollution (EFCu: 5.6–12.5; EFZn: 2.8–4.3; EFPb: 2.4–5.4; EFCr: 1.1–3.2). Copper pollution was more severe, with high maxima contamination factor (CFCu: 15.1–24.8), probably contributed by copper-based antifouling paints used in fishing vessels. The sediments in the inner fishing port are categorized as having considerable ecological risk and toxicity (mERMq: 0.61–0.91; ΣTU: 7.5–11.7) that can potentially cause adverse effects on benthic organisms. Qianzhen Fishing Port sediments can be characterized as high Cu/Fe and Pb/Fe, moderate Zn/Fe, and high total grease content, indicating that the potential sources of heavy metals are primarily antifouling paints and oil spills from the fishing vessels. This study provides valuable data for pollution control, remediation, and environmental management of fishing ports.

Hot spots of unseen fishing vessels

Abstract: Illegal, unreported, and unregulated (IUU) fishing incurs an annual cost of up to US$25 billion in economic losses, results in substantial losses of aquatic life, and has been linked to human rights violations. Vessel tracking data from the automatic identification system (AIS) are powerful tools for combating IUU, yet AIS transponders can be disabled, reducing its efficacy as a surveillance tool. We present a global dataset of AIS disabling in commercial fisheries, which obscures up to 6% (>4.9 M hours) of vessel activity. Disabling hot spots were located near the exclusive economic zones (EEZs) of Argentina and West African nations and in the Northwest Pacific, all regions of IUU concern. Disabling was highest near transshipment hot spots and near EEZ boundaries, particularly contested ones. We also found links between disabling and location hiding from competitors and pirates. These inferences on where and why activities are obscured provide valuable information to improve fisheries management.

OUP accepted manuscript

Abstract: Abstract The western Baltic Sea cod (WBC) stock is at historically low levels, mainly attributed to high fishing pressure and low recruitment. Stable stock assessment metrics suggested recovery potential, given appropriate fisheries management measures. However, changing environmental conditions violate stability assumptions, may negatively affect WBC, and challenge the resource management. The present study explored 42 years of changes in WBC biological parameters. WBC body condition gradually decreased over the last decades for juveniles and adults, with a rapid decrease in recent years when a single cohort dominated the overfished stock. The hepato-somatic index and the muscle weight decreased by 50% and 10% in the last 10 years, respectively, suggesting severely decreasing energy reserves and productivity. The changes in energy reserves were associated with changes in environmental conditions (increase in bottom water temperature, expansion of hypoxic areas during late summer/autumn), and changes in diet composition (less herring). A key bottleneck is the warming and longer-lasting summer period when WBC, trapped between warmed shallow waters and hypoxic deeper waters, have to mobilize energy reserves to account for reduced feeding opportunities and thermal stress. Our results suggest that stock recovery is unlikely to happen by fisheries management alone if environmental trajectories remain unchanged.

From plate to plug: The impact of offshore renewables on European fisheries and the role of marine spatial planning

Abstract: Offshore renewables (OR), such as offshore wind farms, are a key pillar to address increasing energy demands and the global transition to a carbon-free power sector. The transition to ever more occupied marine spaces, often facilitated by marine spatial planning (MSP), increases the conflict potential with free ranging marine sectors such as fisheries. Here, we quantified for the first time the direct impact of current and future OR development on fisheries across European seas. We defined direct impact as the average annual fishing effort (h) overlapping with OR planning sites and applied an ensemble approach by deploying and harmonising various fisheries data to optimise spatial coverage for the European seas. The North Sea region will remain the centre of OR development for a long time, but a substantial increase of conflict potential between these sectors will also occur in other European sea basins after 2025. Across all sea basins, fishing fleets deploying bottom contacting gears targeting flatfish and crustaceans are and will be affected the most by the already constructed and planned OR. Our results provide a solid basis towards an understanding of the socio-economic effects of OR development on European fisheries. We argue that European MSP processes need to adopt common strategies to produce standardised and harmonised socio-economic data to understand implications of OR on free-ranging marine activities such as fisheries.

Managing fisheries for maximum nutrient yield

Abstract: Abstract Wild‐caught fish are a bioavailable source of nutritious food that, if managed strategically, could enhance diet quality for billions of people. However, optimising nutrient production from the sea has not been a priority, hindering development of nutrition‐sensitive policies. With fisheries management increasingly effective at rebuilding stocks and regulating sustainable fishing, we can now begin to integrate nutritional outcomes within existing management frameworks. Here, we develop a conceptual foundation for managing fisheries for multispecies Maximum Nutrient Yield (mMNY). We empirically test our approach using size‐based models of North Sea and Baltic Sea fisheries and show that mMNY is predicted by the relative contribution of nutritious species to total catch and their vulnerability to fishing, leading to trade‐offs between catch and specific nutrients. Simulated nutrient yield curves suggest that vitamin D, which is deficient in Northern European diets, was underfished at fishing levels that returned maximum catch weights. Analysis of global catch data shows there is scope for nutrient yields from most of the world's marine fisheries to be enhanced through nutrient‐sensitive fisheries management. With nutrient composition data now widely available, we expect our mMNY framework to motivate development of nutrient‐based reference points in specific contexts, such as data‐limited fisheries. Managing for mMNY alongside policies that promote access to fish could help close nutrient gaps for coastal populations, maximising the contribution of wild‐caught fish to global food and nutrition security.

Impacts of COVID-19 on the Fisheries and Aquaculture Sector in Developing Countries and Ways Forward

Abstract: Fish is a major source of food and nutritional security for subsistence communities in developing countries, it also has linkages with the economic and supply-chain dimensions of these countries. Burgeoning literature has revealed the adverse impacts of COVID-19 on the fisheries and aquaculture sector, which serves as the major source of income and employment for numerous people globally. This study has employed a systematic literature review of the overall impacts of COVID-19 on the fisheries and aquaculture sector in developing countries using the PRISMA approach. This study reveals that COVID-19 has posed numerous challenges to fish supply chain actors, including a shortage of inputs, a lack of technical assistance, an inability to sell the product, a lack of transportation for the fish supply, export restrictions on fish and fisheries products, and a low fish price. These challenges lead to inadequate production, unanticipated stock retention, and a loss in returns. COVID-19 has also resulted in food insecurity for many small-scale fish growers. Fish farmers are becoming less motivated to raise fish and related products as a result of these cumulative consequences. Because of COVID-19’s different restriction measures, the demand and supply sides of the fish food chain have been disrupted, resulting in reduced livelihoods and economic vulnerability. In order to assist stakeholders to cope with, adapt to, and build resilience to pandemics and other shocks, this study offers policy recommendations to address the COVID-19-induced crisis in the fisheries and aquaculture sector.

Seventy years of tunas, billfishes, and sharks as sentinels of global ocean health

Abstract: Fishing activity is closely monitored to an increasing degree, but its effects on biodiversity have not received such attention. Using iconic and well-studied fish species such as tunas, billfishes, and sharks, we calculate a continuous Red List Index of yearly changes in extinction risk over 70 years to track progress toward global sustainability and biodiversity targets. We show that this well-established biodiversity indicator is highly sensitive and responsive to fishing mortality. After ~58 years of increasing risk of extinction, effective fisheries management has shifted the biodiversity loss curve for tunas and billfishes, whereas the curve continues to worsen for sharks, which are highly undermanaged. While populations of highly valuable commercial species are being rebuilt, the next management challenge is to halt and reverse the harm afflicted by these same fisheries to broad oceanic biodiversity. Description Conservation works Tuna and billfishes are large species that have long been targeted by fisheries, whereas sharks, which are also large fishes, have tended to be considered as by-catch or nontarget species. Juan-Jorda et al. used an approach that monitors yearly changes in the International Union for Conservation of Nature Red List status to estimate population status for these three groups (see the Perspective by Burgess and Becker). After almost three decades of decline, tuna and billfishes have begun to recover because of proactive fisheries management approaches. Sharks, however, which have received much less conservation attention, have continued to decline. These results both reinforce the value of conservation and management and emphasize the need for immediate implementation of these approaches for sharks. —SNV The IUCN Red List index tracks the recovery of tunas and billfishes as the status of undermanaged sharks continues to decline. INTRODUCTION Recent biodiversity assessments show unprecedented loss of species, ecosystems, and genetic diversity on land but it remains unclear how widespread such patterns may be in the oceans. There is an urgent need to develop surveillance indicators to track the health of ecosystems in the marine realm, including changing extinction risk of marine species. These will allow evaluation of progress toward achieving global goals and commitments established by the Convention of Biological Diversity (CBD) and Sustainable Development Goals (SDGs) to halt and reverse marine biodiversity loss. RATIONALE Highly monitored oceanic fisheries comprising iconic predatory tunas, billfishes, and sharks yield an opportunity to support the development of linked sets of pressure and ecological state indicators capable of measuring progress toward global biodiversity and sustainability targets. We derived a continuous Red List Index (RLI) based on International Union for Conservation of Nature (IUCN) Red List categories and criteria for tracking yearly changes in extinction risk of oceanic tunas, billfishes, and sharks over the past 70 years to assess the health of oceanic biodiversity. Furthermore, by assessing the sensitivity and responsiveness of the RLI (state indicator) to fishing mortality (pressure indicator) and assessing the alignment between the most recent Red List status and fishery exploitation status of tunas, billfishes, and shark populations, we offer decision-makers a robust set of linked pressure-state indicators for tracking biodiversity loss and recovery in oceanic ecosystems. RESULTS We find that since 1950, the global extinction risk of oceanic predatory fishes has continuously worsened as a result of rising and excessive fishing pressure, up until the late 2000s when management actions reduced fishing mortality, allowing for recovery of tunas and billfishes. However, sharks remain undermanaged and their extinction risk continues to rise. Our findings reveal a core problem and ongoing challenge in the management of oceanic multigear and multispecies fisheries. Whereas target species are increasingly sustainably managed to ensure maximum yields, the functionally important shark species being captured incidentally by the same fisheries continue to decline as a result of insufficient management actions. Furthermore, our study also connects annual changes in global extinction risk with changes in fishing mortality over the last 70 years, demonstrating how the global RLI trajectory of oceanic predatory fishes is highly sensitive and responsive to fishing mortality. CONCLUSION Although halting biodiversity loss by rebuilding highly valuable commercial tuna and billfish species has been achieved, the next challenge is to halt declines in shark species by setting clear biodiversity goals and targets as well as implementing science-based conservation and fishery management measures and international trade regulations. Unless an effective mitigation hierarchy of management actions to reduce shark mortality is urgently implemented (and adapted to the complexity of each fishery and shark species), their risk of extinction will continue to increase. Furthermore, we demonstrate a high alignment and complementarity between the current population-level Red List status and fishery exploitation status of tunas, billfishes, and sharks, when applied at the same scale. Although we do not propose that the RLI be used to manage fish populations, this strong alignment eliminates any technical barrier for use of the RLI by policy-makers for tracking CBD and SDG targets. Global Red List Index (RLI) of oceanic predatory fishes for tracking progress toward global biodiversity and sustainability targets. (A) The global population-level RLI (state indicator) closely tracks changes in fishing mortality (pressure indicator) for 52 oceanic tuna, billfish, and shark populations over the last 70 years, thus providing decision-makers with a linked set of pressure-state indicators for tracking the health of oceanic biodiversity. The population-level RLI was reversed in 2008 following a reduction in fishing mortality after implementation of fisheries management measures in tuna regional fisheries management organizations. The horizontal gray line denotes F/FMSY =1, FMSY being fishing mortality (F) which produces the maximum sustainable yield (MSY). (B) Global continuous species-level RLI of tunas, billfishes, and oceanic sharks (seven, six, and five species, respectively) tracking yearly changes in extinction risk over 70 years and the global episodic RLI of oceanic sharks and rays (21 and 10 species, respectively) estimated in 1980, 2005, and 2018. An RLI value of 1 indicates that a given taxa qualifies as least concern (that is, not expected to become extinct in the near future), whereas an RLI value of zero indicates that all taxa have gone extinct.

Towards climate-smart, three-dimensional protected areas for biodiversity conservation in the high seas

Abstract: Marine species are moving rapidly in response to warming, often in different directions and with variations dependent on location and depth. Given the current impetus to increase the area of protected ocean to 30%, conservation planning must include the 64% of the ocean beyond national jurisdictions, which in turn requires associated design challenges for conventional conservation to be addressed. Here we present a planning approach for the high seas that conserves biodiversity, minimizes exposure to climate change, retains species within reserve boundaries and reduces conflict with fishing. This is developed using data from across four depth domains, considering 12,932 vertebrate, invertebrate and algal species and three climate scenarios. The resultant climate-smart conservation areas cover 6% of the high seas and represent a low-regret option that provides a nucleus for developing a full network of high-seas marine reserves. Protecting the ocean from increasing threats requires the development of high-seas marine reserve networks. An approach that optimizes biodiversity, minimizes climate change exposure and reduces fisheries conflict enables low-regret climate-smart conservation areas to be identified.

Resist‐accept‐direct (RAD) considerations for climate change adaptation in fisheries: The Wisconsin experience

Abstract: Decision- makers in inland fisheries management must balance ecologically and socially palatable objectives for ecosystem services within financial or physical constraints. Climate change has transformed the potential range of ecosystem services available. The Resist- Accept- Direct (RAD) framework offers a foundation for responding to climate- induced ecosystem modification; however, ecosystem trajectories and current practices must be understood to improve future decisions. Using Wisconsin's diverse inland fisheries as a case study, management strategies for recreational and subsistence fisheries in response to climate change were reviewed within the RAD framework. Current strategies largely focus on resist actions, while future strategies may need to shift toward accept or direct actions. A participatory adaptive management framework and co- production of policies between state and tribal agencies could prioritise lakes for appropriate management action, with the goal of providing a landscape of diverse fishing opportunities. This knowledge co- production represents a process of social learning requiring substantial investments of funding and time.

Impact of Ocean Warming, Overfishing and Mercury on European Fisheries: A Risk Assessment and Policy Solution Framework

Abstract: Previous studies have shown that multiple-environmental stressors are expected to have significant and geographically differential impacts on the health and abundance of marine species. In this paper, we analyze the combined impacts of ocean warming, overfishing and mercury pollution in European waters by projecting the impacts of climatic and non-climate drivers on marine species in European waters. Our findings suggest that the impacts vary widely depending on different species and their mean temperature tolerance (MTT). We find for instance, that more than 5 temperate benthopelagic species including, bobtail squids (Sepiida) frogfishes (Lophius) great Atlantic scallop (Pecten maximus) red mullet (Mullus barbatus barbatus) and common octopus (Octopus vulgaris) are affected (i.e., weakens their resilience to climate change) by the increase in sea surface temperature (SST) under RCP 8.5 in 2050 and 2100. Mercury contamination was estimated to increase in some species (e.g., ∼50% in swordfish), exceeding mercury consumption guideline thresholds (>1 mg/kg). This negative impact may limit the capacity of fisheries and marine ecosystem to respond to the current climate induced pollution sensitivity. An implication of our study is that the international community should strengthen a global ban on mercury emissions under the mandate of the Minamata Convention, comparable to the United Nations framework for persistent organic pollutant emission sources. Ongoing global efforts aimed at minimizing carbon footprint and mercury emissions need to be enhanced in concert with a reduction in fishing intensity to maintain effective conservation measures that promote increased resilience of fisheries to climate change and other stressors.