Abstract

There are 31 marine mammal and 2 sea turtle species that occur in the waters of British Columbia (BC), Canada, of which 13 populations are protected under the Species at Risk Act (SARA). Population recovery is often hindered by a lack of understanding of the environmental and human factors affecting these animals (e.g., physical and noise disturbance, vessel strikes, entanglements, disease outbreaks). In January 2008, Fisheries and Oceans Canada (DFO) officially established the BC Marine Mammal Response Network (BCMMRN) to provide a consistent framework for tracking and responding to strandings, entanglements and other marine mammal and sea turtle incidents, within BC's nearshore waters and along its 27,000 km of coastline. The network is a collaboration involving federal, provincial, and municipal governments, researchers, conservation and wildlife rescue groups, and the general public. In 2009, there were 480 unique cases of dead or distressed marine mammals reported to the BCMMRN. This is a 275% increase over the average annual number of cases reported between the inception of SARA in 2003 and the establishment of this coast-wide program in 2008. The majority of reported cases were investigated verbally, with further response actions as determined by regional priorities. A total of 41% of all cases involved on-scene responses comprised of: 109 live animal assessments, 104 rehabilitation cases, 82 external carcass examinations, 61 necropsies, 10 disentanglements, and 2 on-site euthanizations. Over half of all cases (56%) were reported during summer months (July-September). The increased number of reports coincides with a seasonal influx of migrating whales and increased vessel traffic and fishing effort in BC waters. The southern region of the province recorded 69% of all cases: 26% South Vancouver Island, 23% Lower Mainland, and 20% East Vancouver Island. Southern BC contains the majority of the province's human population and boating intensity, therefore this region is expected to yield a higher number of reports by the general public. Pinniped reports comprised the majority of cases (79%), which is likely due to the large seal and sea lion populations in BC waters and their proximity to populated areas. Harbour seals were the most commonly reported species (42%). Cetacean reports represented 19% of all cases, with humpback whales (32%) and killer whales (24%) being the most frequently reported. These species are the primary focus of whale watching activities and their distribution often overlaps with fishing activities resulting in increased incidents and entanglements. Reported human-related interactions (HI) accounted for 30% of all cases, half of which were confirmed through investigations. Almost half (48%) of the overall HI reports involved some form of entanglement, while 32% were attributed to disturbance (i.e., close approach, feeding, touching, swimming-with, or shooting). There were 11 reported vessel strikes, 5 of which involved baleen whales. Efforts to increase coast-wide reporting of marine mammal and sea turtle incidents, combined with proper incident data collection and management, will help to better assess marine mammal and sea turtle threats in BC waters--an important step towards effective population recovery, threat mitigation and overall species management.

Acknowledgements

The authors would like to thank the entire BCMMRN membership for their reporting, response, investigative, and analytical contributions to the program. Special thanks to Eva Stredulinsky for her considerable efforts in collating and mapping 2009 data.