This deliverable provides an overview of the various Discard Mitigation Strategies (DMS) that have been analysed and investigated in the various case studies. The DMSs are proposed and examined as case specific approaches to support the implementation of the European Landing Obligation (LO). The DMSs represent potential approaches to reduce unvanted catches through fishing gear technology (WP3) changes in fishing patterns (WP4), by finding efficient solutions for handling unavoidable unwanted onboard (WP5), and through identifying existing a (...)
This deliverable provides an overview of the various Discard Mitigation Strategies (DMS) that have been analysed and investigated in the various case studies. The DMSs are proposed and examined as case specific approaches to support the implementation of the European Landing Obligation (LO). The DMSs represent potential approaches to reduce unvanted catches through fishing gear technology (WP3) changes in fishing patterns (WP4), by finding efficient solutions for handling unavoidable unwanted onboard (WP5), and through identifying existing and novel ways to utilize unwanted catches (WP6).
This deliverable represents thus a synthesis of the work developed in these four “innovation” Work Packages, summarised by region. The technical details of the various approaches can be found in the corresponding deliverables from these WPs and where applicable, in scientific publications.
The work has been diverse, and not all tasks / work package have been performed in each case study. But in every case studies, significant amounts of new knowledge have been developed about the possible technical and tactical approaches to reduce discards and/or to best utilise them in the value chain. A number of approaches are specific to a given issue in a given case study, but there are also many commonalities and some developments are of interest at a much wider scale than the case study.
In the Azores case study, several mitigation measures to the Landing Obligation were assessed for the bottom hook-and-line fisheries. The main technical measures analysed hook size and hook shape. Fishing experiments performed by the DiscardLess team proved that the J-hooks, currently used in the fishery, are better than circle hooks to limit deep-water shark bycatch. The main tactical measures included spatial and vertical/depth avoidance strategies. Spatial avoidance strategies appear of limited potential for blackspot seabream. For deep-water sharks, habitat suitability models showed large distribution, mostly influenced by depth, of most species, and some areas with high number of deep-water sharks. Some areas of high conflict (high number of zero TAC species and high fishing effort) could be identified. The large number of species included within the zero TAC limitation, and the high mobility of some species, render spatial avoidance measures difficult to implement. However,depth avoidance strategies could be more promising. The most promising measure to avoid unwanted catch appears to be the conversion of bottom longlining to handlining., which has also been ongoing for some years. Data collected as part of the DiscardLess project in the Azores were used to support requests for exemptions asked by the Regional Government of the Azores, which were granted in 2018.
In the Eastern Mediterranean Sea (Agean Sea) case study, selectivity analyses have shown that both 40mm square and 50mm diamond meshes, compared to the 40mm diamond, would increase escapement and reduce discards. There seems to be little scope for avoidance strategies. Some feasibility analyses were performed for the use of discards at shore. investigating options for small quantities of unwanted landings in small harbours. Two options were suggested: fishmeal/fishoil and silage, using small mobile production plants. However, the initial investments costs are important and the expected returns are limited.
In the Western Mediterranean Sea (Balearic Islands / Gulf of Lions), the problem of small-sized fish is mainly related to hake, and discard rates for all other species under the LO are low, except for horse mackerel. Most trawlers from the Balearic Islands have already changed to 40 mm square mesh cod-end, but there is still scope for improving the fishery selectivity and avoid juveniles of hake and mackerel by changing the mesh size and shape or introducing other devices such as panels and grids. Spatial management is widely used and supported in the Mediterranean as a strategy to reduce unwanted catches. Fishers highly support the mapping of juvenile hotspots based on scientific knowledge. DiscardLess developed a number of spatial models in this area, and made them available through Apps consultable via Internet. However, forecasting the impact of discard avoidance management on the sustainability of trawler fisheries is challenging, requiring data, time and trained human-resources.
In the Bay of Biscaye case study, most of the work performed by DiscardLess dealt with the use of unwanted catches in the value chain. A catalogue of more than 30 different utllisations was published online, and a systematic approach was developed for a rapid appraisal of which of the possible utilisations might be preferable in a case-by-case approach, depending on the quantity, quality and variability of the expected volumes of unwanted catches, of the existing and required infrastructures and logistics, and of the potential market demand. Some trials were conducted, producing e.g. fish pulp and hydrolysates out of unwanted mackerel and juvenile hake brought to land. Different options for the adequate handling of unwanted catches onboard were proposed, and an automatic system at shore for the identification and classification of unwanted fish that would be landed iced and preserved as normal catches was developed and successfully tested. Some cost-efficient DNA tests for the rapid detection of the presence/absence of a species in a mix were also developed.
The mixed nature of the species targeted by demersal fisheries in the Celtic Sea case study results in numerous challenges with the introduction of the Landing Obligation. It is likely that a combination of improved gear selectivity and the adoption of alternative fishing strategies will be required to avoid some of the unwanted catches, and to maximise on fishing opportunities under the LO. There is certainly no one-size fits all solution, and it is likely that gear and behaviour adaptations will mitigate some, but not all problems with choke species and <MCRS fish. DiscardLess provided resources in the form of the selectivity manual and mapping apps for the Celtic Sea, but further collaborations with industry will be required to ensure that future developments of mapping applications meet the needs of interested stakeholders in appropriate formats and time frames. By sharing information on occurrences of undersize fish or spawning aggregations for example, coupled with the information provided in the maps developed in this project, fishers should be much better equipped to avoid choke species and juvenile fish. A major problem in the Celtic Sea remains that due to quota allocation rules as well as stock status, all Member States encounter choke issues, while TAC is globally undershot for a number of species. There is thus some potential for management measures to help mitigate the impacts of the LO.
In the Eastern English Channel case study as well, the mixed nature of the fisheries results in numerous challenges with the introduction of the Landing Obligation. One of the main obstacle to gear selectivity improvement is the diversity of species (with large differences in size, shape, market value and management regime), which have made attempts to improve gear selectivity little conclusive in the area. Some „challenge“ experiments to test the Landing Obligation in real conditions showed issues in increasing workload and storage capacity onboard. DiscardLess performed numerous interviews and studies dedicated to the mapping of unwanted catches including some user-friendly maps apps. Fishermen engaged in collaboration for designing adequate knowldge plateforms and scenarios given their limited sets of options for changing fishing zones, given the large amount of other usages of the maritime space in the area.
In the North Sea/West of Scotland case study, many different DMS analyses were conducted. but mainly involving desk studies and laboratory experiments rather than actual trials at sea. Major progresses in knowlegde on gear selectivity was brought together and shared, including the publication of numerous factsheets on selective devices and some in-depth analyses of how and why the various elements of a trawls modify selectivity by affecting fish behaviour. Extensive experiments of the use of light were conducted, in order to test the avoidance/attraction reactions of fish to different types of light (color, intensity, flash etc). The results demonstrate some differences in behaviour between different species of fish, which could be a promising avenue for improving catch composition. Several studies were published advancing knowledge on the spatial distribution of choke species and unwanted catches, not least using fine-scale fisheries data coming from different previous Danish pilot trials involving Electronic Monitoring and weighting-packing at sea. Regarding the valoriation of unwanted catches in the value chain, a project was run in collaboration with the harbour of Hanstholm (DK), which established new facilities for the storage and delivery of fish in 2017. At present, most unwated catches and rest raw products are used for feed in the mink farms. The project also foresaw initially the rebuilding of the processing deck of a trawler, but the discard levels in that fishery remain limited and not worth the investment. Finally, a large part of the work performed by DiscardLess in this case study related to the issue of Monitoring, Control and Surveillance. This included both the publication of various studies on experiences and progresses with Fully Documented Fisheries and Electronic Monitoring, and major progresses achieved on the use of DNA technology for the characterisation of species in a mix (e.g. bulk or silage) and the quantification of the relative biomass of each species. This represents a promising break-through for the control and traceability of unanted catches in the value chain.
Alltogether, important progresses in scientific knowledge has been achieved in a number of topics, including e.g. fish behaviour (swimming, escapement and reaction to light), fish mortality and survival, fine-scale spatial distribution of key species, handling and flesh properties of a number of different fish species, DNA characterisation etc. As such, it must be recognised that the landing Obligation has triggered significant advances in fundamental biological, ecological and technological knowledge, way beyond the state of the art at the time of the reform of the Common Fishery Policy in 2013. It is certain that this research activity would not have taken place without the political pressure to reduce discards.
However, in spite of these intense scientific and technical analyses, it is obvious that the discarding issue has not been solved yet. The complexity of the issue is immense, and there are still many technical, economic, social, cultural, psychological, institutional and political barriers that hinder the achievement of the objectives of the landing obligation. There are thus no simple and unique „one-size-fits-all“ technical solutions that would solve all issues and without economic impact. But there are many small steps that can be taken, which individually can contribute to reducing discards.
Box 1: Highlights
Box 2: The Methods/Approaches followed
Box 3: How these results can be used and by whom
These sections by case studies will be made as individual chapters and published on http://www.discardless.eu/where-do-we-work, allowing for a regional synthetic overview of the knowledge available.
This is of interest for all actors in a region, stakeholders and policy makers, in the frame of the regionaliation of the CFP, to(Read More)