Salmon Steward is the official publication of the Pacific Salmon Foundation in British Columbia, Canada
Issue link: http://digital.canadawide.com/i/1182504
salmon Steward magazine 9 R ecent poor health of Southern Resident Killer Whales coupled with declines in their top prey – Chinook – suggests the whales may be lacking an adequate food supply. This summer, the Pacific Salmon Foundation provided a $150,000 grant for research on the availability of Chinook for orcas. The study uses tech from PSF's Salish Sea Marine Survival Project, Canada's Ocean Tracking Network and Kintama Research, and was underwritten by a $5-million contribution made to PSF by the B.C. government. "We wanted to see how their behaviour changes when there are predatory killer whales nearby," explains Scott Hinch, director of UBC's Pacific Salmon Ecology and Conservation Lab. "We studied how fast they were moving and how deep they travelled. We also are using tissue samples and genomic tools to identify which river they came from, how healthy and how much energy the fish had stored in their systems, and what stressors could be affecting their behaviour." This data will complement studies by UBC's Brian Hunt on energy content of Chinook, and by Frances Juanes and PhD student Kelsie Murchy on the impact of underwater noise, as killer whales use sound frequencies to locate fish (see below). All will combine to help ascertain if there is a shortage of Chinook, or if shipping noise is interfering with the whales' ability to hunt. SOUND SCIENCE In 2018, DFO announced $26.6 million in funding to investigate the impact of underwater noise on marine mammals, with Southern Resident Killer Whales a focus on the West Coast. But what about the impact on their favourite meal – Chinook? University of Victoria PhD student Kelsie Murchy is looking for answers with funding through PSF's Salish Sea Marine Survival Project. Noise from marine creatures plays a vital ecological role, but increasingly, human noise has been added to the mix. "We know that some fish species produce sound for different reasons, such as mating calls and to signal aggression," says Murchy. "We also know that salmon can hear. But we don't know if our increasingly noisier waters are affecting their behaviour." Murchy will share resources with the British Columbia Conservation Foundation to conduct her study (p. 7). "BCCF's studies have resulted in a lot of information on timing and mortality of Cowichan Chinook as they migrate up-river to spawn, and the acoustic tags will add key behavioural information," says Murchy. "Acoustic tags can show us if Chinook are slowing down, speeding up, swimming deeper – essentially how they're behaving under different conditions." In her study, Murchy will use underwater speakers to play shipping noise and whale noises, then observe how Cowichan Chinook react. n NOISY WATERS, HUNGRY WHALES Above: Stephen Johnston releases a Chinook caught and tagged in Port Renfrew with researchers from UBC. Left: Kelsie Murchy (right) is sharing data and acoustic tagging resources with the BCCF to study impacts of noise on Cowichan Chinook. Is human-generated distortion keeping killer whales from zeroing in on Chinook? This drone photo of a Southern Resident Killer Whale interacting with Chinook was captured off the mouth of the Fraser River. (2) JAMIESON ATKINSON