Biomass removal by dolphins and fisheries in a Mediterranean Sea coastal area: do dolphins have an ecological impact on fisheries?

• 1. Dolphins are often claimed to compete with fisheries, including through removal of substantial biomass. To calculate the biomass removed by fisheries and the degree of resource overlap with dolphins in a coastal area of Greece, estimates of dolphin abundance based on photographic capture–recapture were combined with an assessment of fishing effort and catch.
• 2. The estimated total biomass consumed annually by local dolphin populations – 15 short‐beaked common dolphins and 42 common bottlenose dolphins – was 15.5 and 89.8 tonnes, respectively. The total biomass removed by the local fishing fleet (307 fishing boats) was 3469.2 tonnes, i.e. about 33 times greater than that removed by dolphins.
• 3. Dolphins removed 2.9% of the total biomass, fisheries 97.1%. Nine purse seiners (representing only 3% of the active fishing fleet) were responsible for 31.9% of biomass removal. Similarity of biomass composition between dolphins and fisheries was expressed by a Pianka index of 0.46 for common dolphins and 0.66 for bottlenose dolphins.
• 4. Overlap differed according to fishing gear. Common dolphin overlap was higher with purse seiners (0.82), and lower with beach seiners (0.31), bottom trawlers (0.11) and trammel boats (0.06). There was virtually no overlap with longliners (0.02). Bottlenose dolphin overlap was higher with trammel boats (0.89) and bottom trawlers (0.75), and lower with longliners (0.38), purse seiners (0.24) and beach seiners (0.18). There was minimal overlap (0.12) between the two dolphin species.
• 5. This study suggests that ecological interactions between dolphins and fisheries in this coastal area have minor effects on fisheries. Conversely, prey depletion resulting from overfishing can negatively affect dolphins. Fisheries management measures consistent with national and EU legislation are proposed to ensure sustainability and to protect marine biodiversity. Copyright © 2010 John Wiley & Sons, Ltd.

     

Masked,diluted and drowned out: how global seafood trade weakens signals from marine ecosystems

Nearly 40% of seafood is traded internationally and an even bigger proportion is affected by international trade, yet scholarship on marine fisheries has focused on global trends in stocks and catches, or on dynamics of individual fisheries, with limited attention to the link between individual fisheries, global trade and distant consumers. This paper examines the usefulness of fish price as a feedback signal to consumers about the state of fisheries and marine ecosystems. We suggest that the current nature of fisheries systems and global markets prevent transmission of such price signals from source fisheries to consumers. We propose several mechanisms that combine to weaken price signals, and present one example – the North Sea cod – to show how these mechanisms can be tested. The lack of a reliable price feedback to consumers represents a challenge for sustainable fisheries governance. We therefore propose three complimentary approaches to address the missing feedback: (i) strengthening information flow through improved traceability and visibility of individual fishers to consumers, (ii) capitalizing on the changing seafood trade structures and (iii) bypassing and complementing market mechanisms by directly targeting citizens and political actors regarding marine environmental issues through publicity and information campaigns. These strategies each have limitations and thus need to be pursued together to address the challenge of sustainability in global marine fisheries.     

Aerial drone technology can assist compliance of trap fisheries

Illegal fishing is a global issue that threatens the viability of fishing industries and biodiversity conservation. Management agencies typically use on‐ground surveillance to monitor and minimise illegal fishing practices, the efficacy of which may be enhanced by integrating emerging remote sensing technology. Affordable drones may contribute to cost‐effective detection of illegal fishing activity and associated gear, although their application has yet to be evaluated in many types of fisheries. Here, the utility of drones for the detection of crab traps and floats set in a shallow estuary was quantitatively tested, and the effects of survey altitudes, cameras and monitor screens on detection rates were determined. It was found that drone flight altitude and float colour influenced the detection rates of common crab trap floats, with infrared cameras improving the detection of floats camouflaged by black paint. However, the type of monitor screen used by the drone operator had no influence on the detection of crab traps. Overall, it appears drones can contribute to cost‐effective compliance in estuarine trap fisheries, and the approach can contribute to evidence‐based standard operating procedures.     

Fish spawning aggregations: where well‐placed management actions can yield big benefits for fisheries and conservation

Marine ecosystem management has traditionally been divided between fisheries management and biodiversity conservation approaches, and the merging of these disparate agendas has proven difficult. Here, we offer a pathway that can unite fishers, scientists, resource managers and conservationists towards a single vision for some areas of the ocean where small investments in management can offer disproportionately large benefits to fisheries and biodiversity conservation. Specifically, we provide a series of evidenced‐based arguments that support an urgent need to recognize fish spawning aggregations (FSAs) as a focal point for fisheries management and conservation on a global scale, with a particular emphasis placed on the protection of multispecies FSA sites. We illustrate that these sites serve as productivity hotspots – small areas of the ocean that are dictated by the interactions between physical forces and geomorphology, attract multiple species to reproduce in large numbers and support food web dynamics, ecosystem health and robust fisheries. FSAs are comparable in vulnerability, importance and magnificence to breeding aggregations of seabirds, sea turtles and whales yet they receive insufficient attention and are declining worldwide. Numerous case‐studies confirm that protected aggregations do recover to benefit fisheries through increases in fish biomass, catch rates and larval recruitment at fished sites. The small size and spatio‐temporal predictability of FSAs allow monitoring, assessment and enforcement to be scaled down while benefits of protection scale up to entire populations. Fishers intuitively understand the linkages between protecting FSAs and healthy fisheries and thus tend to support their protection.     

The global contribution of forage fish to marine fisheries and ecosystems

Forage fish play a pivotal role in marine ecosystems and economies worldwide by sustaining many predators and fisheries directly and indirectly. We estimate global forage fish contributions to marine ecosystems through a synthesis of 72 published Ecopath models from around the world. Three distinct contributions of forage fish were examined: (i) the ecological support service of forage fish to predators in marine ecosystems, (ii) the total catch and value of forage fisheries and (iii) the support service of forage fish to the catch and value of other commercially targeted predators. Forage fish use and value varied and exhibited patterns across latitudes and ecosystem types. Forage fish supported many kinds of predators, including fish, seabirds, marine mammals and squid. Overall, forage fish contribute a total of about $16.9 billion USD to global fisheries values annually, i.e. 20% of the global ex‐vessel catch values of all marine fisheries combined. While the global catch value of forage fisheries was $5.6 billion, fisheries supported by forage fish were more than twice as valuable ($11.3 billion). These estimates provide important information for evaluating the trade‐offs of various uses of forage fish across ecosystem types, latitudes and globally. We did not estimate a monetary value for supportive contributions of forage fish to recreational fisheries or to uses unrelated to fisheries, and thus the estimates of economic value reported herein understate the global value of forage fishes.     

Strengthening the synergies among global biodiversity targets to reconcile conservation and socio‐economic demands

1. Most of the world's nations adopted the 20 Aichi global biodiversity targets to be met by 2020, including the protection of at least 10% of their coastal and marine areas (Target 11) and the avoidance of extinction of threatened species (Target 12). However, reconciling these biodiversity targets with socio‐economic demands remains a great dilemma for implementing conservation policies.
2. In this paper, Aichi Targets 11 and 12 were simultaneously addressed using Brazil's exclusive economic zone as an example. Priority areas for expanding the current system of marine protected areas within the country's eight marine ecoregions were identified with data on threatened vertebrates under different scenarios. Additionally, the potential effects of major socio‐economic activities (small? and large‐scale fishing, seabed mining, and oil and gas exploration) on the representation of conservation features in proposed marine protected areas were explored.
3. Areas selected for expanding marine protected areas solely based on biodiversity data were different (spatial overlap from 62% to 93%) from areas prioritized when socio‐economic features were incorporated into the analysis. The addition of socio‐economic data in the prioritization process substantially decreased opportunity costs and potential conservation conflicts, at the cost of reducing significantly (up to 31%) the coverage of conservation features. Large? and small‐scale fisheries act in most of the exclusive economic zone and are the major constraints for protecting high‐priority areas.
4. Nevertheless, there is some spatial mismatch between areas of special relevance for conservation and socio‐economic activities, suggesting an opportunity for reconciling the achievement of biodiversity targets and development goals within the intricate Brazilian seascape by 2020 and beyond.

     

Key biodiversity areas as globally significant target sites for the conservation of marine biological diversity

• 1. Recent approaches to the planning of marine protected area (MPA) networks for biodiversity conservation often stress the need for a representative coverage of habitat types while aiming to minimize impacts on resource users. As typified by planning for the Australian South‐east Marine Region, this strategy can be manipulated by political processes, with consequent biased siting of MPAs. Networks thus created frequently possess relatively low value for biodiversity conservation, despite significant costs in establishment and maintenance.
• 2. Such biases can be minimized through application of the data‐driven and species‐based concept of key biodiversity areas (KBAs).
• 3. By mapping locations of threatened species and populations that are highly aggregated in time or space, the KBA process allows marine sites of global biodiversity significance to be systematically identified as priority conservation targets. Here, the value of KBAs for marine conservation planning is outlined, and guidelines and provisional criteria for their application provided.

Copyright © 2008 John Wiley & Sons, Ltd.     

The sceptical optimist: challenges and perspectives for the application of environmental DNA in marine fisheries

Application of environmental DNA (eDNA) analysis has attracted the attention of researchers, advisors and managers of living marine resources and biodiversity. The apparent simplicity and cost‐effectiveness of eDNA analysis make it highly attractive as species distributions can be revealed from water samples. Further, species‐specific analyses indicate that eDNA concentrations correlate with biomass and abundance, suggesting the possibility for quantitative applications estimating abundance and biomass of specific organisms in marine ecosystems, such as for stock assessment. However, the path from detecting occurrence of an organism to quantitative estimates is long and indirect, not least as eDNA concentration depends on several physical, chemical and biological factors which influence its production, persistence and transport in marine ecosystems. Here, we provide an overview of basic principles in relation to eDNA analysis with potential for marine fisheries application. We describe fundamental processes governing eDNA generation, breakdown and transport and summarize current uncertainties about these processes. We describe five major challenges in relation to application in fisheries assessment, where there is immediate need for knowledge building in marine systems, and point to apparent weaknesses of eDNA compared to established marine fisheries monitoring methods. We provide an overview of emerging applications of interest to fisheries management and point to recent technological advances, which could improve analysis efficiency. We advise precaution against exaggerating the present scope for application of eDNA analysis in fisheries monitoring, but also argue that with informed insights into strengths and limitations, eDNA analysis can become an integrated tool in fisheries assessment and management.     

Tropical invertebrate response to marine reserves varies with protection duration,habitat type,and exploitation history

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The unintended consequences of simplifying the sea: making the case for complexity

Many over‐exploited marine ecosystems worldwide have lost their natural populations of large predatory finfish and have become dominated by crustaceans and other invertebrates. Controversially, some of these simplified ecosystems have gone on to support highly successful invertebrate fisheries capable of generating more economic value than the fisheries they replaced. Such systems have been compared with those created by modern agriculture on land, in that existing ecosystems have been converted into those that maximize the production of target species. Here, we draw on a number of concepts and case‐studies to argue that this is highly risky. In many cases, the loss of large finfish has triggered dramatic ecosystem shifts to states that are both ecologically and economically undesirable, and difficult and expensive to reverse. In addition, we find that those stocks left remaining are unusually prone to collapse from disease, invasion, eutrophication and climate change. We therefore conclude that the transition from multispecies fisheries to simplified invertebrate fisheries is causing a global decline in biodiversity and is threatening global food security, rather than promoting it.     

Designation and management of large‐scale MPAs drawing on the experiences of CCAMLR

With the adoption of the United Nations Law of the Sea came the need for effective worldwide control of marine fisheries. Initially centred on single species, the tasks have extended to ecosystem‐based management through the concept of marine‐protected areas into habitats and biodiversity. These diverse requirements have placed enhanced responsibilities on fisheries management organizations. Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) has successfully developed effective management measures for the Southern Ocean but has encountered difficulties in establishing marine‐protected areas. Key to the success of CCAMLR has been the establishment of conservation measures on clearly defined topics through decision making by consensus. It is argued that the problems that CCAMLR has encountered in establishing marine‐protected areas centre on the range of features, in terms of stakeholder interests, to be afforded protection allied to problems with the consensus process. In this paper, the approaches of CCAMLR in converting the conceptual framework of treaty language into practical management measures using consensus are discussed in relation to the manner in which marine‐protected areas might be established within other fisheries management organizations. It is concluded that the most effective approach is as a composite of strictly focussed conservation measures the sum of which cover all facets of a marine‐protected area. This approach has the further advantage that individual components can be changed without opening the whole legal instrument to re‐negotiation.     

A fresh look at inland fisheries and their role in food security and livelihoods

The role of inland fisheries in livelihoods, food security and sustainable development is often overshadowed by the higher profile interest in ocean issues. Whilst inland fisheries' catch and contribution to global nutrition, food security and the economy, are less than that of marine fisheries, global‐level comparisons of fish production obscure considerable livelihood impacts in certain countries and sub‐national areas. To highlight these contributions, this paper synthesizes recent data and innovative approaches for assessing such livelihood contributions and their importance in countries with limited access to ocean resources and aquaculture. Inland fisheries are crucial for many socially, economically and nutritionally vulnerable groups of people around the world, but the challenges in monitoring inland fisheries preclude a complete understanding of the magnitude of their contributions. This situation is rapidly improving with increasing recognition of inland fisheries in development discourses, which has also encouraged research to enhance knowledge on the importance of inland fisheries. We review this work, including collated information published in a recent Food and Agriculture Organization report, to provide an up to date characterization of the state of knowledge on the role of inland fisheries.     

An interview‐based approach assessing interactions between seals and small‐scale fisheries informs the conservation strategy of the endangered Mediterranean monk seal

1. Small‐scale fisheries may pose a serious threat to the conservation of marine mammals. At the same time various factors have led to the decline of small‐scale fisheries, often making them unsustainable. Current rates of biodiversity loss and the reduction of fish stocks and fisheries dictate a thorough understanding of fisheries‐related issues and the implementation of effective management actions.
2. The Mediterranean monk seal is one of the most endangered marine mammals on Earth; its survival in the eastern Mediterranean Sea is threatened by negative interactions with fisheries. A nationwide questionnaire survey among fishers and port police authorities was carried out in Greece to describe the main characteristics of small‐scale fisheries, and to understand the nature and assess the magnitude of negative interactions between the monk seal and these fisheries. Questionnaire information was verified by a second round of interviews during landings.
3. The main attributes of the fishers, their fishing boats, and their practices were characteristic of the small‐scale fisheries sector. Overfishing was considered the main reason for fish‐stock reduction, and negative interactions with marine mammals was considered the main issue for the fishing sector.
4. Monk seals were present, caused damage, and got accidentally entangled in fishing gear throughout Greece. Damage to fishing gear was recorded mainly during spring and summer, and on average affected 21% of all fishing trips and 1% of nets deployed during a fishing trip.
5. Based on these results, the implementation of general and specific nationwide fishery management and conservation actions are proposed. These actions are mainly aimed at improving fish stock status, changing the behaviour of the fishers, and mitigating seal–fishery interactions in Greece, while promoting the recovery of the Mediterranean monk seal in the eastern Mediterranean Sea.

     

Conservation of aquatic invertebrates: concerns,challenges and conundrums

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Fish conservation in freshwater and marine realms: status,threats and management

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Ecoviability for ecosystem‐based fisheries management

Reconciling food security, economic development and biodiversity conservation is a key challenge, especially in the face of the demographic transition characterizing many countries in the world. Fisheries and marine ecosystems constitute a difficult application of this bio‐economic challenge. Many experts and scientists advocate an ecosystem approach to manage marine socio‐ecosystems for their sustainability and resilience. However, the ways by which to operationalize ecosystem‐based fisheries management (EBFM) remain poorly specified. We propose a specific methodological framework—viability modelling—to do so. We show how viability modelling can be applied using four contrasted case‐studies: two small‐scale fisheries in South America and Pacific and two larger‐scale fisheries in Europe and Australia. The four fisheries are analysed using the same modelling framework, structured around a set of common methods, indicators and scenarios. The calibrated models are dynamic, multispecies and multifleet and account for various sources of uncertainty. A multicriteria evaluation is used to assess the scenarios’ outcomes over a long time horizon with different constraints based on ecological, social and economic reference points. Results show to what extent the bio‐economic and ecosystem risks associated with the adoption of status quo strategies are relatively high and challenge the implementation of EBFM. In contrast, strategies called ecoviability or co‐viability strategies, that aim at satisfying the viability constraints, reduce significantly these ecological and economic risks and promote EBFM. The gains associated with those ecoviability strategies, however, decrease with the intensity of regulations imposed on these fisheries.     

Global marine yield halved as fishing intensity redoubles

There is widespread concern and debate about the state of global marine resources and the ecosystems supporting them, notably global fisheries, as catches now generally stagnate or decline. Many fisheries are not assessed by standard stock assessment methods including many in the world's most biodiverse areas. Though simpler methods using widely available catch data are available, these are often discounted largely because data on fishing effort that contributed to the changes in catches are mostly not considered. We analyse spatial and temporal patterns of global fishing effort and its relationship with catch to assess the status of the world's fisheries. The study reveals that fleets now fish all of the world's oceans and have increased in power by an average of 10‐fold (25‐fold for Asia) since the 1950s. Significantly, for the equivalent fishing power expended, landings from global fisheries are now half what they were a half‐century ago, indicating profound changes to supporting marine environments. This study provides another dimension to understand the global status of fisheries.     

The status of marine biodiversity in the Eastern Central Atlantic (West and Central Africa)

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Does MPA mean ‘Major Problem for Assessments'? Considering the consequences of place‐based management systems

Marine protected areas (MPAs) have been increasingly proposed, evaluated and implemented as management tools for achieving both fisheries and conservation objectives in aquatic ecosystems. However, there is a challenge associated with the application of MPAs in marine resource management with respect to the consequences to traditional systems of monitoring and managing fisheries resources. The place‐based paradigm of MPAs can complicate the population‐based paradigm of most fisheries stock assessments. In this review, we identify the potential complications that could result from both existing and future MPAs to the science and management systems currently in place for meeting conventional fisheries management objectives. The intent is not to evaluate the effects of implementing MPAs on fisheries yields, or even to consider the extent to which MPAs may achieve conservation oriented objectives, but rather to evaluate the consequences of MPA implementation on the ability to monitor and assess fishery resources consistent with existing methods and legislative mandates. Although examples are drawn primarily from groundfish fisheries on the West Coast of the USA, the lessons are broadly applicable to management systems worldwide, particularly those in which there exists the institutional infrastructure for managing resources based on quantitative assessments of resource status and productivity.     

The contribution of cephalopods to global marine fisheries: can we have our squid and eat them too?

Cephalopods are a key component of marine food webs, providing sustenance for myriad marine species. Cephalopods are also of increasing economic importance as evidenced by the rapid rise in their global landings over recent decades. If fisheries continue on this trajectory, conflicts may transpire among cephalopod and finfish fisheries, particularly in ecosystems where cephalopods are highly valuable both directly as a landed commodity and indirectly as prey for other harvested species. We provide the first measure of the ecosystem services that cephalopods contribute to fisheries in 28 marine ecosystems, both as a commodity and an ecological support service. We also evaluate how current demands on cephalopods compare to mid‐20th century conditions. We find that cephalopod contributions to fisheries vary widely, but are substantial in many ecosystems. Commodity and supportive services provided by cephalopods contributed as much as 55% of fishery landings (tonnes) and 70% of landed values ($USD). The contribution of cephalopods as a commodity was generally greatest in the coastal ecosystems, whereas their contribution as a supportive service was highest in open ocean systems. Further, the commodity and supportive services provided by cephalopods to fisheries landings increased in most of the coastal ecosystems between the mid‐20th century (years 1960–70) and contemporary periods (years 1990–2004), indicating the rising demand for cephalopods. Current demands have no historical precedent and ecosystems in which cephalopods are highly exploited as a targeted resource and as an ecological support service should be further evaluated to prevent the unsustainable development of marine fisheries within them.