Towards an enhanced management of recreational whale watching: The use of ecological and behavioural data to support evidence-based management actions

Recognition of the potential disturbance from whale-based tourism has stimulated the discussion of whether whale watching remains ‘no take’. Here we use observations and passive acoustic surveillance of tourism activities of foraging gray whales (Eschrichtius robustus) on the west coast of Vancouver Island to better understand the pressures on whales that are repeatedly subject to aerial and vessel-based viewing. Pressure from the fleet was greatest for low prey years, whereby fewer whales were subject to a greater number of encounters with whale watching vessels. The pressure on operators for close encounters was also greater during these years. The acoustic recordings found that whale watching vessels shaped the soundscape, with a distinct diurnal pattern. Acoustic reactions by the whales were also noted. Cow-calf pairs showed increased calling rate in the presence of vessels in the feeding bay, with calling rate of single foraging whales increasing as vessel number, particularly those engaged in whale watching, increased. These responses have implications for energetics, communication success. The implications of acoustic disturbance from whale watching has yet to be well defined, but it is only one of many stressors that gray whales are subject to. The results of this study lead us to argue for greater evidence-based management of whale watching; restrictions on encounters; noise emission limitations; requiems for the whales, and a greater interpretative component for passengers. The aggregate and cumulative effects of disturbance should also be emphasized in vessel-whale interaction guidelines, with the most vulnerable individuals removed from the viewing resource altogether.