In this manual we describe the different stages of the fish capture process, highlight how different parts of the gear may influence selection and identify possible design changes which can alter the selectivity of the gear. The intention is to make fishermen, net makers and fisheries managers more aware of the possible modifications that can be made to their gears so that they can design and develop gears with a selective performance suitable for their particular fishery.
The 2013 Common Fisheries Policy introduced a landing obligation on a range of species, bringing more focus on the full accountability of all catches. To investigate the potentials and challenges of these paradigm shifts, a 6-months ‘unrestricted gear’ trial was performed in Denmark in 2015. Twelve trawlers were challenged to test their own solutions to reduce unwanted bycatch and/or choke species, while maintaining profitable. The participating fishers tested different options depending on their fishery and the type of issues they faced individually, and adjusted their test fishery over time through incremental small steps. Nine vessels reduced discard ratio in the test fishery, one showed no dif- ference between test and control fishery, while two vessels displayed an increase in discard ratio. Catch compositions also differed, with fewer “choke species” occurring in the test fisheries and a more valuable size composition. Ultimately, despite smaller landings in multiple vessels, no vessel showed reduction in value-per-unit-effort (VPUE) and one Baltic vessel significantly increased the VPUE. This trial showed that relax- ing technical regulations combined with proper incentives has a potential to provide some flexibility to cope with the landing obligation, where unwanted catches could be reduced to some extent without negative effects on economic viability.
A key challenge for fisheries science and management is the access to reliable and verifiable catch data. In science, the challenge is to collect reliable, precise and traceable data to provide sound advice. In management, the challenge is that catch documentation is necessary to enforce regulations. Currently, catch inspection at sea, self-reporting through e-log and on-board observers are the primary methods to document catches at sea. However, at-sea control and on-board observers are costly and have limited coverage, while self-reporting is susceptible to fraud and provides limited coverage. New cost-effective methods are currently emerging involving Remote Electronic Monitoring (REM) and on-board cameras. Previous studies have tested REM with promising results. However, evaluation of the potential biases of REM is needed before full benefits can be obtained. We deployed REM with on-board cameras on 14 fishing vessels and were able to inspect 56% of 1523 hauls made in the 6 month trial period, using an estimated 582 man-hours of video audit. The results showed an overall good agreement between the fishers self-reported discards and the video inspectors discard estimates. However, there was large variation in precision between individual vessels and species. Additionally, trial setup and process errors were shown to have a large effect on the precision of the video inspectors discard estimates. Nevertheless, despite challenges, REM was evaluated to have the potential to streamline monitoring and scientific documentation in a medium-size fishing fleet.
This study focuses on Danish fishery inspectors and on fishers with Remote Electronic Monitoring (REM) experience, whose opinions are less well known. Their views on the landing obligation and on the use of REM were investigated using interviews and questionnaires, and contrasted to some fishers without REM experience. 80% of fishery inspectors and 58% of REM-experienced fishers expressed positive views on REM. 9 out of 10 interviewed fishers without REM experience were against REM. Participation in a REM trial has not led to antipathy towards REM. Fishery inspectors saw on-board observers, at-sea control and REM as the three best solutions to control the landing obligation but shared the general belief that the landing obligation cannot be enforced properly and will be difficult for fishers to comply with. The strengths and weaknesses of REM in this context are discussed.
Discard bans have been proposed as part of management policies aimed at balanced harvest (BH). Nationwide discard bans exist in several coun- tries, including Chile, the European Union, Norway, and New Zealand. We analysed experiences from these countries to determine whether or not discard bans are in contradiction with BH, based on six aspects: policy objectives, species/sizes applicability, accompanying technical measures, at- sea monitoring and control, and possible impacts. When discard bans are fully implemented, fishing operations change to more selective fishing, typically targeting bigger individuals of main commercial species. This is consistent with the primary objective of many discard policies, i.e. to reduce unwanted catch. In contrast, proponents of BH argue that broader catch diversity, a product of a widespread harvest strategy, should be sought to avoid major impacts on the ecosystem. Our analysis demonstrates that the scope of discard bans is often limited to main commercial species, al- though usually they can be extended to include more ecosystem components. Some of the policies examined also prohibit the use of unwanted catches for human consumption, thus limiting their effective use. However, the implementation of discard bans requires high levels of at-sea mon- itoring and effective control, and/or strong incentives to fish more selectively, neither of which applied in most cases examined. We conclude that if discard bans were set differently, they could contribute to fishery management policies aiming at BH. Their goals should be in line with BH, i.e. to reach a wider global harvest pattern, or at least be established within management regimes that promote high compliance. Finally, the extent to which a discard ban contributes to achieve BH depends also on the relative importance of the ecosystem benthic and megafauna components.
Achieving single species maximum sustainable yield (MSY) in complex and dynamic fisheries targeting multiple species (mixed fisheries) is challenging because achieving the objective for one species may mean missing the objective for another. The North Sea mixed fisheries are a representative example of an issue that is generic across most demersal fisheries worldwide, with the diversity of species and fisheries inducing numerous biological and technical interactions. Building on a rich knowledge base for the understanding and quantification of these interactions, new approaches have emerged. Recent paths towards operationalizing MSY at the regional scale have suggested the expansion of the concept into a desirable area of “pretty good yield”, implemented through a range around FMSY that would allow for more flexibility in management targets. This article investigates the potential of FMSY ranges to combine long-term single-stock targets with flexible, short-term, mixed-fisheries management requirements applied to the main North Sea demersal stocks. It is shown that sustained fishing at the upper bound of the range may lead to unacceptable risks when technical interactions occur. An objective method is suggested that provides an optimal set of fishing mortality within the range, minimizing the risk of total allowable catch mismatches among stocks captured within mixed fisheries, and addressing explicitly the trade-offs between the most and least productive stocks.
This is the reference document of the Workshop on "The discard ban and its impact on the Maximum Sustainable Yield objective on fisheries" of 16th June 2016, organised by the Committee on Fisheries (COMPECH) and the Policy Department B (PECH Research) of the European Parliament.
It is structured in three parts:
Landing obligation (LO) has become a core element on the Common Fisheries Policy (CFP). In this work a bioeconomic simulation tool is used to anticipate the effects of LO in a particular fleet that by its nature is likely to be highly affected by its implementation. These effects are measured in terms of biologic, economic and fleet indicators. Results show how LO has a negative short term effect in the economic performance of the fleet (the bad). That the exemption and flexibilities foreseen in the CFP alleviate, in the short term, the effects of the choke species and the redistribution effects created (the good). Furthermore, results show that there are private incentives to improve the selectivity and to reduce the discard levels of the fleets. It is concluded how a breeding ground for a more sustainable and productive system is created (very good).
The article looks at the effect the introduction of the landing obligation has had on EU fisheries for the last year. It tries to answer these questions: is the landing obligation on its way to reaching its goal? Has unwanted catch been reduced (and probably fishing mortality too)? It also makes some considerations over the effect that the introduction of the landing obligation had on ICES work as the main provider of advice on fishing opportunities in Europe.
A global assessment of fishing patterns and fishing pressure from 110 different Ecopath models, representing marine ecosystems throughout the world and covering the period 1970 – 2007, show that human exploitation across trophic levels (TLs) is highly unbalanced and skewed towards low productive species at high TLs, which are around two TLs higher than the animal protein we get from terrestrial farming. Overall, exploitation levels from low trophic species were <15% of production, and only 18% of the total number of exploited groups and species were harvested >40% of their production. Generally, well-managed fisheries from temperate ecosystems were more selectively harvested at higher exploitation rates than tropical and upwelling (tropical and temperate) fisheries, resulting in potentially larger long-term changes to the ecosystem structure and functioning. The results indicate a very inefficient utilization of the food energy value of marine production. Rebuilding overfished components of the ecosystem and changing focus to balancing exploitation across a wider range of TLs, i.e. balanced harvesting, has the potential to significantly increase overall catches from global marine fisheries.
Since “balanced harvest” was proposed in 2010 as a possible tool in the operationalization of the Ecosystem Approach to Fisheries (EAF), the concept gained extensive international attention. Because maintaining ecosystem structure and achieving maximum sustainable yields have become two of the key international legal obligations in fisheries management, balanced harvest is as topical as ever. An international workshop on balanced harvest, organised by the IUCN Fisheries Expert Group at FAO headquarters in 2014, reviewed the progress in the field and discussed its prospects and challenges. Several articles in this theme set, mostly based on presentations from the workshop, discuss ecological, economical, legal, social, and operational issues surrounding the key management goals. Progress is being made on understanding of the theoretical underpinnings of balanced harvest and its practical feasibility. Yet, a fundamental debate on the concept of balanced harvest continues. In order to move the EAF forward, we anticipate and encourage further research and discussion on balanced harvest and similar ideas.
Under the ecosystem approach to fisheries, an optimal fishing pattern is one that gives the highest possible yield while having the least structural impact on the community. Unregulated, open-access African inland fisheries have been observed to sustain high catches by harvesting a broad spectrum of species and sizes, often in conflict with current management regulations in terms of mesh and gear regulations. Using a size- and trait-based model, we explore whether such exploitation patterns are commensurable with the ecosystem approach to fisheries by comparing the impacts on size spectrum slope and yield with the different size limit regimes employed in the Zambian and Zimbabwean sides of man-made Lake Kariba. Long-term multispecies data under fished and unfished conditions are used to compare and validate the model results. Both model and observations show that the highest yields and low structural impact on the ecosystem are obtained by targeting small individuals in the community. These results call for a re-evaluation of the size-based management regulations that are ubiquitous in most fisheries.
Conventional fisheries management encourages highly selective fishing patterns for various purposes, such as increase relative yield, reduce unwanted by‐catch, protect various species or sizes and rebuild ecosystems. Recent empirical and theoretical studies, however, show increasing evidence that selective removals of targeted components have unintended adverse effects on stocks, fish communities and the ecosystem. Based on case studies from artisanal African freshwater fisher ies, and results from dynamic size‐based models, this chapter supports the renewed suggestion that an application of a more balanced fishing pattern will mitigate adverse effects and enhance food security better than increased selectivity. Contrary to common belief, small‐scale unregulated artisanal fisheries, with a high diversity of seasonally adapted fishing methods, are probably the closest empirical examples we have of an optimal exploitation pattern with the least disruptive effects on the structure of the ecosystem. As such, they are among the best examples of an ecosystem approach to fisheries that we have.
In this report (In Danish) we gather knowledge and experience from fishing gear selectivity trials conducted in Danish waters over the last decade. The primary focus is on the by-catch of cod in trawl fisheries, but information has been collected for several other commercial species. It is thus possible to identify gears that can be used in cases where other species shall be avoided. In addition to a description of results from the different trials, the catalogue contains predictions for size selection in a wide range of mesh sizes, -shapes and -openings for several species central to the Danish fishery.