In NE Atlantic and Mediterranean European fisheries, discarding occurs mainly because the catch is of no commercial value, quota caps are reached, and because the potentially commercial species are either below MCRS or are of low commercial value (Catchpole et al. 2005; Tsagarakis et al 2103; Sánchez et al. 2007).

Unwanted catches are detrimental to the productivity of stocks, by killing juvenile individuals before their optimum production potential is achieved (i.e. production forgone). For instance, under the current trawl selection pattern, undersize individuals predominate in the catches of hake and red mullet in the Mediterranean, especially during the periods of recruitment to the bottom (Sala and Lucchetti 2011). In the European Atlantic, high-grading of catches subject to quotas results in discarding smaller individuals, even when they are of legal size, because of market reasons (Catchpole et al. 2005).

Likewise, low selective fishing gears are detrimental to threatened species (marine mammals, sea turtles, seabirds), which are unintentionally caught and released with low chances of survival (Tudela et al. 2005; Snape et al. 2013). An additional ecological effect of discarding practices is the case of seabirds, for example, that have become used to exploit discards as a predictable foraging resource, instead of traditional “natural” food sources, and their populations are suffering artificial increases, which affect the structure of marine communities (inter alia, by interference competition). Also, food subsidies between marine and terrestrial ecosystems can alter entire trophic webs (case of hyperpredation: Arcos et al. 2008, Oro et al. 2013).

Some fishing operations generate important discards of habitat-forming invertebrates by fishing on sensitive habitats (maërl bottoms, sea-grass bottoms, cold corals) (Barberà et al. 2003). On the other hand, from a socio-economic point of view, a fishery without unwanted catches is more efficient in time and labour, because the time to sort out catches decreases significantly (Macher et al. 2008).

European fisheries are transitioning to reducing discards and bringing all catches to land obligatorily (“landings obligation”: Common Fisheries Policy reform, EU Regulation 1380/2013). Given the impossibility to completely avoid unwanted catches and the fact that Common Fisheries Policy will progressively phase out discards of commercial species subject to quota or MCRS (except in cases where high survivorship after discarding is demonstrated) (EU Reg. 1380/2013; Condie et al. 2013a), it is necessary to devise technical/technological solutions, along with economic and social incentives, to gradually eliminate unwanted catches. Combining technical/technological solutions, producers’ and consumers’ awareness, and the economic premium of discards-free fishing has the potential to considerably reduce unwanted catches and facilitate a more ecologically sound harvesting regime.

The complexity of the problem outlined and the necessity of cutting across science and society boundaries make it necessary to follow a multi-actor approach, whereby scientists, fisheries technologists, fish producers and NGOs work collaboratively to provide the scientific and technical basis to achieve the gradual elimination of discards in European marine fisheries. The project’s overall objective is to minimise unwanted catches by incentivising the adoption of fishing technologies and practices that reduce pre-harvest mortality and post-harvest discards, while avoiding damage to sensitive marine species and habitats. The general approach will be to develop and demonstrate technical/technological and socioeconomic solutions that enable and incentivise the fisher to firstly avoid taking unwanted catch and, where this cannot be reasonably or practically achieved, to utilise it productively and sustainably, but without profit to the producer. The solutions for dealing with unwanted catches should be based on, in order of priority, avoidance, selection and utilization. These solutions will be developed and demonstrated in a case-by-case analysis of the main types of European fisheries, using a multi-actor approach (natural scientists – social scientists – fisheries technologists - local fisheries managers – fish producers – fish consumers) working collaboratively on practical solutions that are technologically feasible, environmentally sustainable and economically viable. The gradual elimination of unwanted catches will be achieved under the following conditions:

a)    technical/technological solutions that enable commercial fisheries to minimise unwanted catches are readily available and economically viable, 
b)    there are strong socio-economic incentives to avoid generating unwanted catches,
c)    unwanted catches brought to land (mandatory under CFP reform) do not have an economic value to the producer, and
d)    the producer has non-monetary incentives to bring all unwanted catches to land.

Fisheries with no unwanted catches will be beneficial to European economy and environment because:

a)    they will enhance the productivity of EU fisheries by reducing the mortality on juvenile fraction of commercial stocks, and align with EU policies and international commitments;
b)    commercial stocks with balanced demographic structure are more resilient to environmental pressure (Hidalgo et al. 2011) and their catches fetch higher price because of larger size (Colloca et al. 2013);
c)    labour costs will be reduced by decreasing the time of sorting on board, especially for bottom trawl fisheries (Macher et al. 2008); and
d)    threatened species and sensitive habitats will suffer less fisheries impact (Kaiser et al. 2003). However, the reduction of discards should not impact negatively on marine fauna, such as seabirds, that have become dependent on discards for their survival, especially endangered species (Bicknell et al. 2013; Votier et al. 2013).