Showing papers on "Fishing published in 2015"

China's aquaculture and the world's wild fisheries

Abstract: China is the world's largest producer, consumer, processor, and exporter of finfish and shellfish (defined here as “fish”), and its fish imports are steadily rising ( 1 – 3 ) China produces more than one-third of the global fish supply, largely from its ever-expanding aquaculture sector, as most of its domestic fisheries are overexploited ( 3 – 6 ) Aquaculture accounts for ∼72% of its reported domestic fish production, and China alone contributes >60% of global aquaculture volume and roughly half of global aquaculture value ( 1 , 3 )

Recovery potential of the world's coral reef fishes

Abstract: Continuing degradation of coral reef ecosystems has generated substantial interest in how management can support reef resilience(1,2). Fishing is the primary source of diminished reef function globally(3-5), leading to widespread calls for additional marine reserves to recover fish biomass and restore key ecosystem functions(6). Yet there are no established baselines for determining when these conservation objectives have been met or whether alternative management strategies provide similar ecosystem benefits. Here we establish empirical conservation benchmarks and fish biomass recovery timelines against which coral reefs can be assessed and managed by studying the recovery potential of more than 800 coral reefs along an exploitation gradient. We show that resident reef fish biomass in the absence of fishing (B-0) averages similar to 1,000 kg ha(-1), and that the vast majority (83%) of fished reefs are missing more than half their expected biomass, with severe consequences for key ecosystem functions such as predation. Given protection from fishing, reef fish biomass has the potential to recover within 35 years on average and less than 60 years when heavily depleted. Notably, alternative fisheries restrictions are largely (64%) successful at maintaining biomass above 50% of B-0, sustaining key functions such as herbivory. Our results demonstrate that crucial ecosystem functions can be maintained through a range of fisheries restrictions, allowing coral reef managers to develop recovery plans that meet conservation and livelihood objectives in areas where marine reserves are not socially or politically feasible solutions.

Gender and small-scale fisheries: a case for counting women and beyond

Abstract: Marine ecosystem–scale fisheries research and management must include the fishing effort of women and men. Even with growing recognition that women do fish, there remains an imperative to engage in more meaningful and relevant gender analysis to improve socio-ecological approaches to fisheries research and management. The implications of a gender approach to fisheries have been explored in social approaches to fisheries, but the relevance of gender analysis for ecological understandings has yet to be fully elaborated. To examine the importance of gender to the understanding of marine ecology, we identified 106 case studies of small-scale fisheries from the last 20 years that detail the participation of women in fishing (data on women fishers being the most common limiting factor to gender analysis). We found that beyond gender difference in fishing practices throughout the world, the literature reveals a quantitative data gap in the characterization of gender in small-scale fisheries. The descriptive details of women’s often distinct fishing practices nonetheless provide important ecological information with implications for understanding the human role in marine ecosystems. Finally, we examined why the data gap on women’s fishing practices has persisted, detailing several ways in which commonly used research methods may perpetuate biased sampling that overlooks women’s fishing. This review sheds light on a new aspect of the application of gender research to fisheries research, with an emphasis on ecological understanding within a broader context of interdisciplinary approaches.

Fishing amplifies forage fish population collapses

Abstract: Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches.

Explaining participation rates in recreational fishing across industrialised countries

Abstract: On average, 10.52% of the total population was found to fish for recreation across the industrialised world (N = 27 countries), amounting to an estimated 118 million (95% confidence interval 81–154 million) people in North America, Europe and Oceania. Participation rates declined with population density and gross domestic product, indicating a negative effect of urbanisation and post-modernisation on fishing interest. Participation rates also declined with increasing median age, average household size and unemployment rate, suggesting resource limitation to constrain participation in fishing. By contrast, two indicators of the cultural importance of fish (fish landings and per capita fish consumption) and an indicator of perceived need for leisure (weekly working hours) were positively correlated with fishing participation. Based on these findings, which explained 60% of the variance in fishing participation across the industrialised world, reduced fishing interest is to be expected with post-industrialisation. Dedicated management and marketing intervention is needed to reverse the track of diminishing fishing interest in industrialised countries.

World squid fisheries

Abstract: Some 290 species of squids comprise the order Teuthida that belongs to the molluscan Class Cephalopoda Of these, about 30-40 squid species have substantial commercial importance around the world Squid fisheries make a rather small contribution to world landings from capture fisheries relative to that of fish, but the proportion has increased steadily over the last decade, with some signs of recent leveling off The present overview describes all substantial squid fisheries around the globe The main ecological and biological features of exploited stocks, and key aspects of fisheries management are presented for each commercial species of squid worldwide The history and fishing methods used in squid fisheries are also described Special attention has been paid to interactions between squid fisheries and marine ecosystems including the effects of fishing gear, the role of squid in ecosystem change induced by overfishing on groundfish, and ecosystem-based fishery management

Mapping Fishing Effort through AIS Data.

Abstract: Several research initiatives have been undertaken to map fishing effort at high spatial resolution using the Vessel Monitoring System (VMS). An alternative to the VMS is represented by the Automatic Identification System (AIS), which in the EU became compulsory in May 2014 for all fishing vessels of length above 15 meters. The aim of this paper is to assess the uptake of the AIS in the EU fishing fleet and the feasibility of producing a map of fishing effort with high spatial and temporal resolution at European scale. After analysing a large AIS dataset for the period January-August 2014 and covering most of the EU waters, we show that AIS was adopted by around 75% of EU fishing vessels above 15 meters of length. Using the Swedish fleet as a case study, we developed a method to identify fishing activity based on the analysis of individual vessels’ speed profiles and produce a high resolution map of fishing effort based on AIS data. The method was validated using detailed logbook data and proved to be sufficiently accurate and computationally efficient to identify fishing grounds and effort in the case of trawlers, which represent the largest portion of the EU fishing fleet above 15 meters of length. Issues still to be addressed before extending the exercise to the entire EU fleet are the assessment of coverage levels of the AIS data for all EU waters and the identification of fishing activity in the case of vessels other than trawlers.

Pollution, habitat loss, fishing, and climate change as critical threats to penguins.

Abstract: Cumulative human impacts across the world's oceans are considerable. We therefore examined a single model taxonomic group, the penguins (Spheniscidae), to explore how marine species and communities might be at risk of decline or extinction in the southern hemisphere. We sought to determine the most important threats to penguins and to suggest means to mitigate these threats. Our review has relevance to other taxonomic groups in the southern hemisphere and in northern latitudes, where human impacts are greater. Our review was based on an expert assessment and literature review of all 18 penguin species; 49 scientists contributed to the process. For each penguin species, we considered their range and distribution, population trends, and main anthropogenic threats over the past approximately 250 years. These threats were harvesting adults for oil, skin, and feathers and as bait for crab and rock lobster fisheries; harvesting of eggs; terrestrial habitat degradation; marine pollution; fisheries bycatch and resource competition; environmental variability and climate change; and toxic algal poisoning and disease. Habitat loss, pollution, and fishing, all factors humans can readily mitigate, remain the primary threats for penguin species. Their future resilience to further climate change impacts will almost certainly depend on addressing current threats to existing habitat degradation on land and at sea. We suggest protection of breeding habitat, linked to the designation of appropriately scaled marine reserves, including in the High Seas, will be critical for the future conservation of penguins. However, large-scale conservation zones are not always practical or politically feasible and other ecosystem-based management methods that include spatial zoning, bycatch mitigation, and robust harvest control must be developed to maintain marine biodiversity and ensure that ecosystem functioning is maintained across a variety of scales.

Biodiversity conservation should focus on no-take Marine Reserves: 94% of Marine Protected Areas allow fishing

Abstract: Conservation needs places where nature is left wild; but only a quarter of coastal countries have no-take Marine Reserves. 'Marine Protected Areas' (MPAs) have been used to indicate conservation progress but we found that 94% allow fishing and thus cannot protect all aspects of biodiversity. Biodiversity conservation should focus on Marine Reserves, not MPAs.

Fuel consumption of global fishing fleets: current understanding and knowledge gaps

Abstract: Compared to a century ago, the world's fishing fleets are larger and more powerful, are travelling further and are producing higher quality products. These developments come largely at a cost of high-fossil fuel energy inputs. Rising energy prices, climate change and consumer demand for ‘green’ products have placed energy use and emissions among the sustainability criteria of food production systems. We have compiled all available published and unpublished fuel use data for fisheries targeting all species, employing all gears and fishing in all regions of the world into a Fisheries and Energy Use Database (FEUD). Here, we present results of our analysis of the relative energy performance of fisheries since 1990 and provide an overview of the current state of knowledge on fuel inputs to diverse fishing fleets. The median fuel use intensity of global fishery records since 1990 is 639 litres per tonne. Fuel inputs to fisheries vary by several orders of magnitude, with small pelagic fisheries ranking among the world's most efficient forms of animal protein production and crustaceans ranking among the least efficient. Trends in Europe and Australia since the beginning of the 21st century suggest fuel use efficiency is improving, although this has been countered by a more rapid increase in oil prices. Management decisions, technological improvements and behavioural changes can further reduce fuel consumption in the short term, although the most effective improvement to fisheries energy performance will come as a result of rebuilding stocks where they are depressed and reducing over-capacity.

Effectively managing angler satisfaction in recreational fisheries requires understanding the fish species and the anglers.

Abstract: Whenever satisfied anglers are an important objective of recreational fisheries management, understanding how trip outcomes influence satisfaction reports is critical. While anglers, generally, pre...

Rethinking length-based fisheries regulations: the value of protecting old and large fish with harvest slots

Abstract: Managing fisheries using length-based harvest regulations is common, but such policies often create trade-offs among conservation (e.g. maintaining natural agestructure or spawning stock biomass) and fishery objectives (e.g. maximizing yield or harvest numbers). By focusing harvest on the larger (older) fish, minimumlength limits are thought to maximize biomass yield, but at the potential cost of severe age and size truncation at high fishing mortality. Harvest-slot-length limits (harvest slots) restrict harvest to intermediate lengths (ages), which may contribute to maintaining high harvest numbers and a more natural age-structure. However, an evaluation of minimum-length limits vs. harvest slots for jointly meeting fisheries and conservation objectives across a range of fish life-history strategies is currently lacking. We present a general age- and size-structured population model calibrated to several recreationally important fish species. Harvest slots and minimum-length limits were both effective at compromising between yield, numbers harvested and catch of trophy fish while conserving reproductive biomass. However, harvest slots consistently produced greater numbers of fish harvested and greater catches of trophy fish while conserving reproductive biomass and a more natural population age-structure. Additionally, harvest slots resulted in less waste in the presence of hooking mortality. Our results held across a range of exploitation rates, life-history strategies and fisheries objectives. Overall, we found harvest slots to represent a valuable option to meet both conservation and recreational fisheries objectives. Given the ubiquitous benefits of harvest slots across all life histories modelled, rethinking the widespread use of minimum-length limits is warranted.

Mitigating unaccounted fishing mortality from gillnets and traps

Abstract: Gillnets and traps often are considered to have fewer holistic environmental impacts than active fishing gears. However, in addition to the targeted catches, gillnets and traps still cause unwanted mortalities due to (i) discarding, (ii) ghost fishing of derelict gear, (iii) depredation, (iv) escaping or dropping out of gear, (v) habitat damage, and potentially (vi) avoiding gear and predation and (vii) infection of injuries sustained from most of the above. Population-level concerns associated with such ‘unaccounted fishing mortalities’ from gillnets and traps have been sufficient to warrant numerous attempts at mitigation. In this article, we reviewed relevant research efforts, locating 130 studies in the primary literature that concomitantly quantified mortalities and their resolution through technical modifications, with the division of effort indicating ongoing concerns. Most studies (85) have focused on discard mortality, followed by ghost-fishing (24), depredation (10) and escape (8) mortalities. The remaining components have been poorly studied (3). All problematic mortality components are affected by key biological (e.g. species), technical (e.g. fishing mechanisms) and/or environmental (e.g. temperature) factors. We propose that these key factors should be considered as part of a strategy to reduce impacts of these gears by first assessing modifications within and then beyond conventional configurations, followed by changes to operational and handling practices. Justification for this three-tiered approach is based not only on the potential for cumulative reduction benefits, but also on the likely ease of adoption, legislation and compliance.

A statistical framework to explore ontogenetic growth variation among individuals and populations: a marine fish example

Abstract: Growth is a fundamental biological process, driven by a multitude of intrinsic (within-individual) and extrinsic (environmental) factors, that underpins individual fitness and population demographics. Focusing on the comprehensive information stored in aquatic and terrestrial organism hard parts, we develop a series of increasingly complex hierarchical models to explore spatial and temporal sources of growth variation, ranging in resolution from within individuals to across a species. We apply this modeling framework to an extensive data set of otolith increment measurements from tiger flathead (Platycephalus richardsoni), a demersal commercially exploited fish that inhabits the warming waters of southeast Australia. We recreated growth histories (biochronology) up to four decades in length from seven fishing areas spanning this species' range. The dominant pattern in annual growth was an age-dependent, allometric decline that varied among individuals, sexes, fishing areas, years, and cohorts. We found ev...

Winners and losers in a world where the high seas is closed to fishing

Abstract: Fishing takes place in the high seas and Exclusive Economic Zones (EEZs) of maritime countries. Closing the former to fishing has recently been proposed in the literature and is currently an issue of debate in various international fora. We determine the degree of overlap between fish caught in these two areas of the ocean, examine how global catch might change if catches of straddling species or taxon groups increase within EEZs as a result of protection of adjacent high seas; and identify countries that are likely to gain or lose in total catch quantity and value following high-seas closure. We find that <0.01% of the quantity and value of commercial fish taxa are obtained from catch taken exclusively in the high seas, and if the catch of straddling taxa increases by 18% on average following closure because of spillover, there would be no loss in global catch. The Gini coefficient, which measures income inequality, would decrease from 0.66 to 0.33. Thus, closing the high seas could be catch-neutral while inequality in the distribution of fisheries benefits among the world's maritime countries could be reduced by 50%.

Effects of Ocean Acidification on Temperate Coastal Marine Ecosystems and Fisheries in the Northeast Pacific

Abstract: As the oceans absorb anthropogenic CO2 they become more acidic, a problem termed ocean acidification (OA). Since this increase in CO2 is occurring rapidly, OA may have profound implications for marine ecosystems. In the temperate northeast Pacific, fisheries play key economic and cultural roles and provide significant employment, especially in rural areas. In British Columbia (BC), sport (recreational) fishing generates more income than commercial fishing (including the expanding aquaculture industry). Salmon (fished recreationally and farmed) and Pacific Halibut are responsible for the majority of fishery-related income. This region naturally has relatively acidic (low pH) waters due to ocean circulation, and so may be particularly vulnerable to OA. We have analyzed available data to provide a current description of the marine ecosystem, focusing on vertical distributions of commercially harvested groups in BC in the context of local carbon and pH conditions. We then evaluated the potential impact of OA on this temperate marine system using currently available studies. Our results highlight significant knowledge gaps. Above trophic levels 2–3 (where most local fishery-income is generated), little is known about the direct impact of OA, and more importantly about the combined impact of multi-stressors, like temperature, that are also changing as our climate changes. There is evidence that OA may have indirect negative impacts on finfish through changes at lower trophic levels and in habitats. In particular, OA may lead to increased fish-killing algal blooms that can affect the lucrative salmon aquaculture industry. On the other hand, some species of locally farmed shellfish have been well-studied and exhibit significant negative direct impacts associated with OA, especially at the larval stage. We summarize the direct and indirect impacts of OA on all groups of marine organisms in this region and provide conclusions, ordered by immediacy and certainty.

The seascape of demersal fish nursery areas in the North Mediterranean Sea, a first step towards the implementation of spatial planning for trawl fisheries.

Abstract: The identification of nursery grounds and other essential fish habitats of exploited stocks is a key requirement for the development of spatial conservation planning aimed at reducing the adverse impact of fishing on the exploited populations and ecosystems. The reduction in juvenile mortality is particularly relevant in the Mediterranean and is considered as one of the main prerequisites for the future sustainability of trawl fisheries. The distribution of nursery areas of 11 important commercial species of demersal fish and shellfish was analysed in the European Union Mediterranean waters using time series of bottom trawl survey data with the aim of identifying the most persistent recruitment areas. A high interspecific spatial overlap between nursery areas was mainly found along the shelf break of many different sectors of the Northern Mediterranean indicating a high potential for the implementation of conservation measures. Overlap of the nursery grounds with existing spatial fisheries management measures and trawl fisheries restricted areas was also investigated. Spatial analyses revealed considerable variation depending on species and associated habitat/depth preferences with increased protection seen in coastal nurseries and minimal protection seen for deeper nurseries (e.g. Parapenaeus longirostris 6%). This is partly attributed to existing environmental policy instruments (e.g. Habitats Directive and Mediterranean Regulation EC 1967/2006) aiming at minimising impacts on coastal priority habitats such as seagrass, coralligenous and maerl beds. The new knowledge on the distribution and persistence of demersal nurseries provided in this study can support the application of spatial conservation measures, such as the designation of no-take Marine Protected Areas in EU Mediterranean waters and their inclusion in a conservation network. The establishment of no-take zones will be consistent with the objectives of the Common Fisheries Policy applying the ecosystem approach to fisheries management and with the requirements of the Marine Strategy Framework Directive to maintain or achieve seafloor integrity and good environmental status.

Evidence of discrete yellowfin tuna (Thunnus albacares) populations demands rethink of management for this globally important resource.

Abstract: Tropical tuna fisheries are central to food security and economic development of many regions of the world. Contemporary population assessment and management generally assume these fisheries exploit a single mixed spawning population, within ocean basins. To date population genetics has lacked the required power to conclusively test this assumption. Here we demonstrate heterogeneous population structure among yellowfin tuna sampled at three locations across the Pacific Ocean (western, central, and eastern) via analysis of double digest restriction-site associated DNA using Next Generation Sequencing technology. The differences among locations are such that individuals sampled from one of the three regions examined can be assigned with close to 100% accuracy demonstrating the power of this approach for providing practical markers for fishery independent verification of catch provenance in a way not achieved by previous techniques. Given these results, an extended pan-tropical survey of yellowfin tuna using this approach will not only help combat the largest threat to sustainable fisheries (i.e. illegal, unreported, and unregulated fishing) but will also provide a basis to transform current monitoring, assessment, and management approaches for this globally significant species.

Understanding the sources and effects of abandoned, lost, and discarded fishing gear on marine turtles in northern Australia

Abstract: Globally, 6.4 million tons of fishing gear are lost in the oceans annually. This gear (i.e., ghost nets), whether accidently lost, abandoned, or deliberately discarded, threatens marine wildlife as it drifts with prevailing currents and continues to entangle marine organisms indiscriminately. Northern Australia has some of the highest densities of ghost nets in the world, with up to 3 tons washing ashore per kilometer of shoreline annually. This region supports globally significant populations of internationally threatened marine fauna, including 6 of the 7 extant marine turtles. We examined the threat ghost nets pose to marine turtles and assessed whether nets associated with particular fisheries are linked with turtle entanglement by analyzing the capture rates of turtles and potential source fisheries from nearly 9000 nets found on Australia's northern coast. Nets with relatively larger mesh and smaller twine sizes (e.g., pelagic drift nets) had the highest probability of entanglement for marine turtles. Net size was important; larger nets appeared to attract turtles, which further increased their catch rates. Our results point to issues with trawl and drift-net fisheries, the former due to the large number of nets and fragments found and the latter due to the very high catch rates resulting from the net design. Catch rates for fine-mesh gill nets can reach as high as 4 turtles/100 m of net length. We estimated that the total number of turtles caught by the 8690 ghost nets we sampled was between 4866 and 14,600, assuming nets drift for 1 year. Ghost nets continue to accumulate on Australia's northern shore due to both legal and illegal fishing; over 13,000 nets have been removed since 2005. This is an important and ongoing transboundary threat to biodiversity in the region that requires attention from the countries surrounding the Arafura and Timor Seas.

Understanding fishing-induced extinctions in the Amazon

Abstract: Science and policy worldwide are influenced by predictions from bioeconomic theory that fishing cannot lead fish populations to extinction because fishing effort inevitably moves away from depleted resources. Yet such predictions contradict evidence of fishing-induced extinctions and in particular a model, called 'fishing-down', that explains historical reductions in mean size of harvested species in tropical multispecies fisheries through the gradual depletion and extinction of large-bodied species. 2. This study analysed data on fisheries for Arapaima spp., the most historically important and overexploited fishes of the Amazon Basin, to evaluate whether they supported bioeconomic or fishing-down predictions. The evaluation was based on census data on arapaima populations and interview data from 182 fishers with respect to fishing practices and management regulations, which were collected in 81 fishing communities covering 1040km 2 of Amazonian floodplains. 3. Arapaima populations were found to be 'depleted' in 76% of the fishing communities, 'overexploited' in 17%, 'well-managed' in 5%, and 'unfished' in only 2%. Population densities were zero (i.e. locally extinct) in 19% of the communities. Twenty-three per cent of the fishers in each community harvested arapaima regardless of population status. Similarly, the percentage of the catch in compliance with the size regulation did not vary with population status, but compliance with the season regulation in communities with 'overexploited' or 'depleted' populations (72%) was lower than in communities with 'well-managed' or 'unfished' populations (97%). 4. These results support fishing-down predictions that fishing pressure continues to occur even when fish populations are depleted. The fishing-down process appeared to occur because of low gear selectivity and larger body-size of target species as well as high species value and low fishing costs. These results and available data elsewhere suggest that fishing-induced extinctions are more common than previously thought, endangering biodiversity and ecosystem functioning. Such extinctions are probably going unnoticed because high levels of illegal fishing, geographic heterogeneity, and data scarcity make their identification difficult. Copyright # 2014 John Wiley & Sons, Ltd.

The role of diversification in dynamic small-scale fisheries: Lessons from Baja California Sur, Mexico

Abstract: Globally, small-scale fisheries are critical for livelihoods and food security yet face increasing uncertainty and variability from processes such as overfishing, globalization, and climate change. Enhancing the number of options for human response through increased access to marine resources, diverse livelihood approaches, and generalist fishing strategies may attenuate the negative effects of change and disturbance. My research explores the relative importance of diversification strategies for achieving resilient small-scale fishing communities and cooperatives of Baja California Sur, Mexico. Specifically, interview data and long-term catch and economic data were used to develop an economic metric of resilience, in addition to income diversification indices, for fishing cooperatives. Fishing cooperative characteristics and environmental conditions were then evaluated as possible predictors of cooperatives’ relative ability to diversify. I found that while diversification was important for risk mitigation and stabilizing income, the ability of cooperatives to specialize during favorable conditions may be important for poverty reduction and wealth accumulation. Thus, the flexibility to move across fishing strategies given changing environmental conditions is important for the adaptive capacity of small-scale fishing cooperatives. My findings will contribute to a better understanding of the institutional arrangements that promote a resilient small-scale fishery, and therefore, will be invaluable for practitioners of small-scale fisheries.

Driving small-scale fisheries in developing countries

Abstract: Small-scale fisheries (SSFs) engage the vast majority of the world’s fishers but are struggling to keep pace with coastal populations, and stocks are declining to levels that threaten reproductive capacity. The provision of food and livelihoods to low-income fishers into the future will be unlikely without radical changes to fisheries policy. We draw on repeating analogies of driving a car to illustrate fundamental reforms needed for driving (managing) small-scale fisheries. SSFs will continue to be unsustainable by relying too heavily on output controls (the ‘brake’). Managers need to move away from routinely using moratoria (i.e. the ‘handbrake’) as a management measure, although these measures may be needed as a last resort. Scientists (‘backseat drivers’) must engage more directly with fishery management agencies to understand their constraints and needs. Resource managers must come to terms with regulating fishing inputs (the ‘accelerator’) by imposing limited-entry rules, vessel limitations or short fishing seasons in addition to sensible output controls. Reforms to resource management will need to entail unpopular measures if small-scale fisheries are to deliver sustained benefits to fishing communities into the future.

Electrotrawling: a promising alternative fishing technique warranting further exploration

Abstract: In trawl fisheries, beam trawls with tickler chains, chain mats or bobbin ropes are used to target flatfish or shrimp. High fuel consumption, seabed disturbance and high discard rates are well-known disadvantages of this fishing technique. These shortcomings are increasingly gaining international public and political attention, especially with the upcoming discard ban in Europe. The most promising alternative fishing technique meeting both the fisherman's aspirations, and the need for ecological progress is pulse fishing with electrotrawls. Here, the mechanical stimulation by tickler chains or bobbins is replaced by electrical stimulation resulting in reduced bottom contact, fuel costs and discards. Although a significant amount of research has been done on electrotrawls and their impact on marine organisms, most data were published in very diverse sources ranging from local non-peer-reviewed reports with a limited distribution to highly consulted international peer-reviewed journals. Therefore, there is a clear need for a comprehensive yet concise and critical overview, covering and summarizing all these data and making these available for the scientific community. This article aims to meet the above goals by discussing the working principle of electric fields, the history of electrotrawls and their current application in the North Sea and impact on marine organisms. It is concluded by elaborating on the opportunities and challenges for the further implementation of this alternative fishing technique.