Evaluating the suitability and performance of entanglement mitigation devices for fixed gear fisheries in Atlantic Canada

Abstract

Entanglement in fishing gear is inhibiting the recovery of North Atlantic right whales (Eubalaena glacialis). Low breaking-strength (LBS) modifications have the potential to reduce severity of entanglements. The first part of this thesis aims to assess if LBS components have sufficient strength to withstand conditions in the Newfoundland and Labrador snow crab (Chionoecetes opilio) fishery by documenting tensions while hauling. Results showed that tension regularly exceeded the 771 kgf LBS threshold when hauling traps, suggesting that they are not suitable for this fishery. The second part involved assessing time-tension line cutters (TTLCs), a double-threshold (time and tension) entanglement mitigation device. Due to their use of hydraulic fluid and the known effect of temperature on its viscosity, a controlled laboratory experiment reflecting the conditions of Atlantic fisheries was conducted to evaluate the effect of temperature on time to cut (TTC). Results revealed that for every unit increase in temperature (1°C), time to cut was reduced by 0.759 min. Additionally, extreme TTC values at the lowest temperature tested showed further development and testing are needed. This thesis presents several novel methods and findings with direct application to one of Canada’s most economically important fisheries and the innovation of entanglement mitigation devices.