Reducing the Mortality and Serious Injury of North Atlantic Right Whales in the Gulf of Maine

Abstract

The North Atlantic right whale (Eubalaena glacialis) is one of the most critically endangered baleen whales. The most pressing threat to this declining population is entanglement. The Atlantic Large Whale Take Reduction Team recommended measures to reduce the entanglement risk to right whales in fixed gear fisheries in the Gulf of Maine. The central recommendation was to reduce the breaking strength of vertical lines used in these fisheries. We collected data on the breaking strength of unmodified line and lines modified with weak points to develop options for Maine fishermen to reduce entanglement risk to right whales. Our study had three goals: (1) develop a baseline dataset of breaking strength for ropes used in Maine; (2) determine the efficacy of five weak point options in reducing the breaking strength of line to the breaking strength target of 1700 pounds of force (lbsf); and (3) examine if a time tension line cutter (TTLC) could be used as a physical weak point. We tested 140 pieces of straight line and 950 weak point samples. As expected, straight line samples were stronger than those with a weak point. All weak points reduced the breaking strength of each type of line, but no weak point option was successful in reducing all samples to 1700 lbsf. The TTLC could be used as a physical weak point in the fishery, but further studies should be conducted on its ease of use for fishermen. Two of the weak points tested effectively reduced breaking strengths across all rope types, but our results suggest the Maine lobster fishery will require a variety of solutions to reduce risk to right whales.