Preliminary observation about the possibility of Antarctic krill escapement from a trawl net

We observed whether Antarctic krill escaped from the trawl net or not using an underwater video camera attached on the trawl net of Japanese commercial trawler Fukuei-maru (4,350.62 GT) in 2011. To avoid the influence of camera lighting on krill behavior, the observation was conducted during daytime. Few krill appeared to escape from posterior part of trawl net. When the trawl net caught dense krill swarms, krill escaped from anterior part of trawl net. Krill were observed to swim actively after they escaped from the net, suggesting their escapement mortality may be low. In 2012, we are trying to develop a method using LED lighting system at our laboratory for the purpose of filed observation of krill escapement at night and in the deep depth, where sun light does not reach.