Effects of fishing rope strength on the severity of large whale entanglements

This study investigated the impact of rope polymer type, breaking strength and diameter in relation to the injury severity of entangled baleen whales, primarily North Atlantic Right whales (Eubalaena glacialis). Fishing gear removed from live and dead entangled whales from the US East Coast and Canadian Maritimes region between 1994 and 2010 were included in this study. Average tested breaking strength of removed rope was 2,616 bs, 26% below strength at manufacture. Median rope diameter was 3/8 in. The breaking strength of ropes was significantly higher for right (4,338 mean lbs) and humpback (3,8520 mean lbs) whales compared to smaller minke whales (2,353 mean lbs). Stronger ropes (7,664 lbs) entangled adult right whales when compared to juveniles (mean 3,446 lbs) and all humpback whales (mean 3,906 lbs). Study results suggest that if ropes with breaking strengths of 1,700 lbs or less were used, the number of life-threatening whale entanglements could be reduced by at least 72%.