Discard sampling of Dutch bottom-trawl and seine fisheries in 2012

In the European Union, the collection of discard data is enforced through the Data Collection Regulation Framework (DCF) of the European Commission (EC). In 2009, revisions to the DCF (2008/949/EG), required member states to increase sampling intensity. To meet this requirement within an affordable budget, the Institute for Marine Resources and Ecosystem Studies (IMARES) 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 and where the fisher’s retained fractions of their discards during some trips. These samples were then purchased off them. This report summarizes data from the discard monitoring programme of Dutch demersal fisheries operating in the North Sea (ICES subarea IV).

In the self-sampling programme in 2012, trips were pre-determined from a reference fleet of 23 participating vessels. In total, 159 trips were sampled, of which 17 trips (11%) were considered invalid due to missing or incomplete information. During the 142 valid self-sampling trips 279 hauls were sampled, typically two hauls per trip. While the majority of samples were taken from beam-trawl vessels with mesh sizes ranging between 70 and 99 mm targeting flatfish, data were collected from nine other metiers as well. These included beam trawls with larger mesh sizes otter trawls (with different target species assemblages) and seines.

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); lemon sole (Microstomus kitt); and solenette (Buglossidium luteum). Among marketable fish, common dab (Limanda limanda) and European plaice (Pleuronectes platessa) were the most frequently discarded species.