Passive Acoustic Gliders Are Effective Monitoring Tools for Dynamic Management Plans Aimed at Mitigating Whale-Vessel Strikes

Abstract

Dynamic management is intended to mitigate the impacts of human activities on wildlife when and where the activities overlap with at-risk species. Amid an ever-growing maritime industry, we researched the performance of mobile underwater passive acoustic gliders as near real-time monitoring assets for the purpose of whale-vessel strike mitigation through dynamic management. Across 580 glider survey days, 30 near real-time acoustic detections of critically endangered North Atlantic right whales (NARWs) triggered 194 days of mandatory 10-knot vessel speed limits in three Canadian Dynamic Shipping Zones (DSZs). We found a high degree of interannual and seasonal variation in NARW acoustic occurrence and vessel slowdowns in the DSZs. Gliders were more effective than aerial surveillance at triggering slowdowns by a factor of 2–5 during fall and summer but were less effective during spring. Our results provide unambiguous evidence that gliders are effective monitoring platforms that can enhance dynamic ocean management goals globally.