Comparative analysis of the impact of trawl and longline fishing on the Barents Sea ecosystem

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In the Barents Sea, bottom fish species are harvested by both bottom trawls and longlines. Despite the similar main target fish species for these gears (cod, haddock, halibut) they differ in selectivity. The species and length composition of catches by trawls and longlines is dissimilar. Because of this, fisheries by bottom trawl and longline have a diverse impact on separate fish stocks and the whole Barents Sea fish fauna. Some fish stocks of the Barents Sea are difficult to access by longlining although they are successfully fished by trawling; in contrast, longlines can be used to target fish species that are present in trawls as a bycatch. In fishery both gears intensively affect the bottom biotope and the biocenoses having formed there. A trawl is an active gear towed at the bottom, whereas a longline lies passively on the ground; therefore a trawl undoubtedly has a greater negative impact on bottom biocenoses. However, unlike a longline, a trawl does not have the disadvantage of catching birds. The paper gives a comparative analysis of the impact of bottom trawling and longlining in the Barents Sea on separate elements of its ecosystem. The effect of those gears on bottom biocenoses, fish stocks, and bird communities was analysed.