Hind-casting the quantity and composition of discards by mixed demersal fisheries in the North Sea

PloS One
Michael R Heath, Robin M Cook

Abstract

Many commercial fisheries seek to maximise the economic value of the catch that they bring ashore and market for human consumption by discarding undersize or low value fish. Information on the quantity, size and species composition of discarded fish is vital for stock assessments and for devising legislation to minimise the practice. However, except for a few major species, data are usually extremely sparse and reliant on observers aboard a small sample of fishing vessels. Expanding these data to estimate total regional discards is highly problematic. Here, we develop a method for utilising additional information from scientific trawl surveys to model the quantities of fish discarded by the commercial fisheries. As a case-study, we apply the model to the North Sea over the period 1978-2011, and show a long-term decline in the overall quantity of fish discarded, but an increase in the proportion of catch which is thrown away. The composition of discarded catch has shifted from predominantly (∼80%) roundfish, to >50% flatfish. Undersized plaice constitute the largest single fraction of discards, unchanged from the beginning of the 20th century. Overall, around 60% of discarded fish are rejected on the basis of size rather than fo...Continue Reading

References

Feb 20, 2004·Nature·Stephen C VotierDavid R Thompson
Jul 25, 2009·Statistics in Medicine·David LunnNicky Best
Oct 15, 2009·Statistics in Medicine·Jon Wakefield
Oct 15, 2009·Statistics in Medicine·Martyn Plummer
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Feb 1, 2011·Current Biology : CB·Nigel Williams
Oct 19, 2013·Ecology Letters·Daniel OroAlejandro Martínez-Abraín
May 14, 2014·Nature Communications·Michael R HeathDouglas C Speirs

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