Anthropogenic threats to humpback whales in the Salish Sea: insights from northeastern Vancouver Island

As humpback whale (Megaptera novaeangliae) populations recover from commercial whaling throughout the North Pacific Ocean, these whales are returning to areas where they were rarely encountered or absent for the past four decades. These areas include the coastal waters of northeastern Vancouver Island (NVI) and more recently, the Salish Sea. The return of humpback whales to coastal waters leads to increased overlap between humpback whales and human activities, including vessel traffic and fisheries. We use data from NVI, an area where humpback whale numbers have been increasing over the past ten years, as an example of the effects of this overlap. Data were collected through dedicated research effort, as well as opportunistically from whale watch vessels. Between 2003 and 2013, we documented a total of 176 humpback whales off NVI. The annual number of individual humpback whales sighted off NVI increased from seven individuals in 2003 to a maximum of 71 individuals in 2011. A minimum of eight vessel strikes and five entanglements in fishing gear were witnessed off NVI since 2006. Fishing gear involved in these entanglements included prawn, crab, and seine gear. A further nine entanglement events can be inferred based on scarring and injuries on whales’ bodies. Due to the intense levels of human activity in the Salish Sea, these anthropogenic threats are likely to negatively impact both the endangered humpback whales and the humans using these coastal waters. They may also have implications for the management of humpback whales and fisheries in the Salish Sea