Results of testing three types of streamer lines for reduction of seabird bycatch in demersal longline fishery

Abstract

The streamer lines of 3 types are tested and compared: i) the model used in the USA Pacific waters; and ii-iii) two new models made of cheaper materials, more accessible in Russia. One new model is similar to the American one but the lateral orange 1/4” Kraton thermoplastic tubes are replaced by orange twisted polyethylene ropes with the diameter 10 mm. Another new model is similar with the former one but its 6 first longest streamers are single instead of double and 1-4 bunches of the yellow polypropylene packing tape (in 6 tapes of 1 m length) are fixed on them. The testing was realized aboard two mid-tonnage vessels for demersal longline fishery in the Far-Eastern Seas of Russia in July-October 2010 and July-August 2013. In total, 223 control longlines with 2 million hooks were set up. The seabird bycatch and frequency of the bird attacks to the bait did not differ significantly between the new models of streamers and the American model, and considerable distinctions in their running abilities were not found, as well, so the streamer lines of easy accessible and cheap materials, able for assembling directly aboard fishing vessels, could be recommended for Russian fishermen for reducing their maintenance charges. Such streamer lines are offered for application to demersal longline fishery in the Far-Eastern Seas of Russia.