The methodic approaches to the estimating traumatic depth of krill passed through the trawl meshes

Fishing for krill Euphasia superba has been conducting using midwater trawls of different constructions including beam-trawl for several last decades. Not all krill in harvesting zone of midwater trawl got to catch during trawling. Depending on stock structure, size and physiological state of krill individuals some part of them could pass through cover of net bag and escape of catch. In contact with threads of the net bag some of them may receive possibly lethal mechanical damage. Proposed method is applicable for rating of krill traumatic damage, received by it during trawling from cover of net bag, only for fishing with hauling of full net for catch extraction. The analogous rating for fishing with fishpump needs developing of special methods of source material obtaining to set experiments. But, taking into account the fact that trawl constructions used for these variants of fishing process are analogous or insignificantly different from the first, obtained results could be interpolated for them too. Picking of krill individuals, passed through meshes of net bag cover of fishing gear was carried out with specially made net bags-catchers (traps), set onto the cover of net bag of a studies trawl. While hauling, caught in these special bags krill is took out and then put into a special baths with sea water for conducting of aquarium studies to determine its survival.

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