漁業者への聞き取り調査から見る日本の沿岸漁業とウミガメの関係

抄録

A nationwide interview survey was conducted from 2009 to 2013 to evaluate the state of sea turtle bycatch in Japanese coastal fisheries. A total of 1,074 fishermen and other industry representatives were interviewed at 175 sites, and 2,087 responses regarding the various fishing methods used were collated. Bycatch frequency of more than 5-10 sea turtles annually per operation was reported in large and small pound net, gill net, bottom trawl, boat seine, surround net, rod and line, and trawl fisheries. The highest bycatch frequency was reported from large pound net fisheries, especially in the Pacific coast of Shikoku, followed by the East coast of Ki-i Peninsula. However, bycatch frequency among large pound net fisheries varied widely by operation. Bycatch mortality rate in large pound nets were also divided, with 30 of 40 valid respondents reporting low or nearly 0% mortality rate, while 5 respondents reported high or nearly 100% mortality rate. Small pound nets also demonstrated a relatively high bycatch frequency, although lower than large pound nets. The findings of this study suggest that the priority for addressing sea turtle bycatch in Japan should be placed on individual large pound nets with high sea turtle mortality. However, mitigation measures for coastal fisheries bycatch should be developed to ensure fish landings, especially since sea turtle nesting activities in Japan are increasing and exhibiting recovery from past trends.