Discards in fisheries - a summary of three decades of research at IMARES and LEI

Discards and the possible ecological and economic effects of discarding are a hot topic in discussions about sustainable fisheries. The perception of the effects of discarding differs between parties and it is influenced by the ecosystem functioning and the state of the species under consideration. This report provides an overview of the current scientific knowledge at IMARES and LEI about discard levels, effects, and discard reduction from an ecological, technical, economic and management perspective. The following Dutch commercial marine wild capture fisheries with active gear are considered: pelagic, beam trawl, otter trawl (demersal fish and nephrops) and shrimp fisheries

The European Landing Obligation. Reducing Discards in Complex, Multi-Species and Multi-Jurisdictional Fisheries

This open access book provides a comprehensive examination of the European Landing Obligation policy from many relevant perspectives. It includes evaluations of its impacts at economical, socio-cultural, ecological and institutional levels. It also discusses the feasibility and benefits of several potential mitigation strategies. The book was timely published, exactly at the time where the Landing Obligation was planned to be fully implemented. This book is of significant interest to all stakeholders involved, but also to the general public of Europe and to other jurisdictions throughout the world that are also searching for ways to deal with by-catch and discard issues

Aanlandingsplicht

De EC heeft verschillende voorstellen gedaan met betrekking tot de vervorming van het Gemeenschappelijk Visserij Beleid. Een van de voorstellen is om vanaf 2014 voor verschillende vissoorten de verplichting tot het aanlanden van alle vangsten in te voeren, ook wel discard ban genoemd. Het ministerie maakt zich zorgen over de gevolgen die dit voorstel kan hebben voor de Nederlandse visserij en heeft IMARES en het LEI gevraagd om extra informatie over discardsvangsten. In dit werkdocument is ingegaan op de hoeveelheid gevangen discards (het deel van de vangst, dat, dood of levend, weer overboord wordt gegooid) per metier en de fluctuatie van de vangst van discards door het jaar heen. De studie is een feitelijke opsomming van de discardsgegevens die bij IMARES bekend zijn. Verder zal de overlevingskans van de gevangen discards centraal staan in dit document. Het ministerie wilde ook graag meer inzicht in de overleving van discards. Een aanlandingsplicht ligt minder voor de hand voor soorten met een hoge overlevingskans. Een literatuurstudie is uitgevoerd die geresulteerd heeft in een korte eerste inventarisatie van de Nederlandse en internationale literatuur over onderzoek naar de overleving van discards. Als laatste is er onderzoek gedaan naar de economische gevolgen in de platvissector voor een discard ban voor alle soorten vergeleken met een discard ban voor alleen de doelsoorten. Er is in deze studie onderscheid gemaakt tussen een discardban voor alle soorten en een discard ban voor de soorten genoemd in het voorstel van de EC

Discard sampling of Dutch bottom-trawl fisheries in 2009 and 2010

In the European Union, the collection of discard data is enforced through the Data Collection Regulation or Framework (DCR/DCF) of the European Commission (EC). To comply with this ruling, approximately ten trips of discard-intensive beam-trawlers are being monitored annually since 1999 (Helmond and Overzee, 2010). In 2009, revisions to the DCF (2008/949/EG), required member states to increase sampling intensity to i) improve the precision of their estimates and ii) the number of sampled métiers. To meet this requirement within an affordable budget, the Institute for Marine Resources and Ecosystem Studies (IMARES, part of Wageningen University and Research) set up a collaborative project between the Dutch fishing industry and the research institute to recruit a ‘reference fleet’ of vessel owners willing to participate in a self-sampling programme. This programme complemented the existing observer programme. In the observer programme, vessels were selected quarterly from a pool of available vessels, whereas in the self-sampling programme, trips were pre-determined from a reference fleet of participating vessels. Missing and/or wrong information precluded the inclusion of 17% and 13% of all self-sampled trips in 2009 and 2010. In total, 9 and 10 observer, and 63 and 132 valid self-sampling trips were completed in 2009 and 2010, respectively. For these remaining valid self-sampled trips, procedures were developed to test whether data quality was comparable with i) other self samples from the reference fleet and ii) comparable observercollected data (i.e. temporally and spatially overlapping trips). In addressing i), there were no unusual patterns in the length frequencies of self-sampled discards of European plaice (Pleuronectes platessa), common dab (Limanda limanda), grey gurnard (Eutrigla gurnardus), and whiting (Merlangius merlangus) in 2009 and2010. In addressing ii), no significant differences in the discard rates of plaice between the two programmes were found. There was no evidence that sampling may have been biased at the vessel level, justifying the decision to present all discard estimates independent of the programme type. While in both programmes the majority of observations were done onboard beam-trawl vessels with mesh sizes ranging between 70 and 99 mm, in the self-sampling programme data from four additional beam- and otter-trawl métiers with two 70-99 and 100-119 mesh size ranges and other target species assemblages (i.e mixed crustaceans and/or demersal fish) were collected. This lead, apart from a considerable increase in sampling effort for some métiers, to an increase in the temporal and spatial spread of sampling. Samples from previously unsampled northern and eastern parts of the North Sea were available. The spatial distribution of sampling locations matched that of the total effort of the fleet for intensively-sampled métiers. In all but two métiers, combined fish and benthos discards exceeded the volume of landings. In contrast, large-mesh beam- and otter trawls (100-119 mm) landed on average more than they discarded. The majority of discards was comprised by benthic (invertebrate ) species such as common starfish (Asteria rubens); sand star (Astropecten irregularis); swimming crab (Liocarcinus holsatus); and serpent star (Ophiura ophiura). Most frequently discarded fish species of no commercial value included: dragonet (Callionymus lyra); grey gurnard (Eutrigla gurnardus); scaldfish (Arnoglossus laterna); and solenette (Buglossidium luteum). Among commercially-valuable fish, common dab (Limanda limanda) and European plaice (Pleuronectes platessa) were the most frequently discarded species

Delineating catch quotas for Dutch demersal fisheries: a theoretical pilot study

A reduction of unwanted catches is a key element of the Common Fisheries Policy reform proposal (EC, 2010). To achieve this, a landing obligation (or discard ban) will be introduced, prohibiting the at-sea disposal of quota-regulated species. Instead these catches shall be brought back to shore and counted against a quota, where applicable

Discard Atlas of North Sea fisheries

The results presented in this discard atlas are based on landings and discards data from the official database of the Scientific, Technical and Economic Committee for Fisheries (STECF) of the European Union. Quantities of landings are derived from the national fisheries statistics which are recorded according to the control regulation (Council Regulation 1224/2009). These include logbook or sales slip records of the volume of landing by species and size grade per management area. Under the European Data Collection Framework, detailed biological data of the biomass, length, age, and species compositions of discards from the most important commercial fisheries are collected via national observer- or self-sampling programmes

Discard sampling of Dutch bottom-trawl and seine fisheries in 2011

In the European Union, the collection of discard data is enforced through the Data Collection Regulation or Framework (DCF) of the European Commission (EC). To comply with this ruling, approximately ten trips of discard-intensive beam-trawlers are being monitored annually since 1999 (Helmond and Overzee, 2010). In 2009, revisions to the DCF (2008/949/EG), required member states to increase sampling intensity to i) improve the precision of their estimates and ii) the number of sampled métiers. To meet this requirement within an affordable budget, the Institute for Marine Resources and Ecosystem Studies (IMARES, part of Wageningen University and Research) set up a collaborative project between the Dutch fishing industry and the research institute to recruit a ‘reference fleet’ of vessel owners willing to participate in a selfsampling programme. In the self-sampling programme, trips were pre-determined from a reference fleet of participating vessels. In total, 155 trips were sampled in 2011, of which 27 trips (17%) were considered invalid due to missing or incomplete information. During the 128 valid self-sampling trips 248 hauls were sampled. While the majority of observations were done on board beamtrawl vessels with mesh sizes ranging between 70 and 99 mm targeting flatfish, data was collected from eight other metiers as well. These included beam trawls with other mesh sizes or target species assemblages, otter trawls and seines. This led, apart from a considerable increase in sampling effort for some métiers, to an increase in the temporal and spatial spread of sampling compared to the previous observer-based sampling. Samples from previously unsampled northern and eastern parts of the North Sea were available now. The spatial distribution of sampling locations matched that of the total effort of the fleet for intensivelysampled métiers. Large-mesh beam- and otter trawls (100-119 mm) on average landed more than they discarded. In the other métiers, combined fish and benthos discards exceeded the volume of landings. The majority of discards comprised of benthic (invertebrate) species such as common starfish (Asteria rubens); sand star (Astropecten irregularis); swimming crab (Liocarcinus holsatus); and serpent star (Ophiura ophiura). Most frequently discarded fish species of no commercial value included: dragonet (Callionymus lyra); grey gurnard (Eutrigla gurnardus); scaldfish (Arnoglossus laterna); solenette (Buglossidium luteum); and lesser weaver (Echiichthys vipera). Among commercially-valuable fish, common dab (Limanda limanda) and European plaice (Pleuronectes platessa) were the most frequently discarded species

Praktijk Netwerk Discards Zuid - Verkennend onderzoek aan visies omtrent discardvermindering en overleving van ondermaatse vis

In het kader van de aangekondigde aanlandingsplicht is het thema overleving van discards van belang voor de visserijsector. In het verleden zijn verschillende experimenten gedaan om de overleving te bepalen van ondermaatse vis die tijdens de visserij aan boord komt en wordt teruggezet in zee. Hierbij is gebruik gemaakt van relatief kleine overlevingsbakken waar deze vis in werd gehouden. Tijdens een langduriger proef in 2005 aan boord van het onderzoekingsvaartuig “Tridens” werd geconstateerd dat de sterfte over een langere tijd plaatsvindt. De vraag bleef of dit door de houderij of door het vangproces werd veroorzaakt. In het visserijbedrijf werd betwijfelt of de overlevingswaarden die met de overlevingsbakken gevonden waren juist zijn en men bepleit de ondermaatse gevangen vis uit te zetten in kooien op de zeebodem en dan de overleving te bestuderen. De belangrijkste vraag die ten grondslag lagen aan dit onderzoek waren: Wat is de overleving van discards