By becoming a member of the BC Wild Killer Whale Adoption Program you will be directly supporting research on wild killer whales. Continuing research will lead to a better understanding of the whales, their place in the ocean ecosystem, and the conservation measures necessary to protect them.

The Blackfish Sounder 

Annual newsletter of the BC Wild Killer Whale Adoption Program

The Blackfish Sounder is the annual Members-Only eight-page newsletter of the BC Wild Killer Whale Adoption Program that is sent to anyone who joins the program by adopting a whale.  Through a mix of news and feature stories, The Blackfish Sounder keeps members up-to-date on what we currently know about killer whales - in B.C. and around the world - and what we hope to learn in the future.  See the article below for a sampling from this year's issues (printed in September 2011).

 

Life's a Grind for Offshore Orcas 

Resident killer whales eat fish and transients prey on marine mammals. But what do offshore killer whales eat? We now have a pretty good idea—and it helps explain a mystery that has puzzled researchers for years.

The “ah-ha” moment came on a 2008 field trip off the northern tip of Haida Gwaii. By chance, Fisheries and Oceans Canada (DFO) researchers John Ford and Graeme Ellis came across a group of five foraging offshore killer whales and decided to follow. They soon noticed a chunk of oily, pinkish-grey tissue pop to the surface.

“We recognized it as a piece of liver,” says Ford. Over the next eight hours, 11 more blobs popped up, some quite large. Occasionally, a whale would grab a blob and take it underwater. “They appeared so far apart in time and distance that we felt most came from different prey animals,” says Ford.

Samples were collected from all of the blobs. Genetic analysis revealed that the blobs were indeed shark liver and came from one species—sleeper shark. And they came from at least nine individual sharks.

Now, fast-forward to 2009 when Alaskan researcher Craig Matkin encountered about 100 offshores in Prince William Sound. They too were leaving a blob trail. Over three hours, Matkin collected seven samples. Again, more shark livers, this time from seven different sleeper sharks.

Sleeper sharks are poorly-studied deep-water fish that are commonly found off the continental slope. They can reach lengths of up to seven metres and are made up of about 30 per cent liver. “About 80 per cent of that is fat,” says Ford, “making them a rich source of food for the whales.”

Is this enough evidence to say that sleeper sharks are a regular menu item for offshore killer whales? Here’s where the plot thickens.

Over the course of killer whale studies off B.C., encounters with offshores have been few and far between. But individuals that have stranded and died have shown an odd feature—their teeth are worn down, often to the gum line with exposed pulp cavities. Even in young animals.

“We never see this in residents or transients,” says Ford, “so we deduced they must be eating something very different.”

Such as sharks. “You just have to touch shark skin to see how it’s like sandpaper,” he says. “Plus, killer whale teeth have a very thin layer of enamel. Once that’s gone, the teeth can probably erode very quickly.”

Together, the evidence strongly suggests that offshore killer whales are shark specialists, says Ford. “It’s been a bit of a detective story, but all the pieces seem to fit.”

 

 

Back Issues of the Blackfish Sounder

Adobe Acrobat Reader is required to view back issues

Blackfish Sounder no.1 - 1993

Blackfish Soudner no.2 - 1994

Blackfish Sounder no.3 - 1995

Blackfish Sounder no.4 - 1996

Blackfish Sounder no.5 - 1997

Blackfish Sounder no.6 - 1998

Blackfish Sounder no.7 - 1999

Blackfish Sounder no.8 - 2000

 

The Blackfish Sounder is the annual Members-Only newsletter of the BC Wild Killer Whale Adoption Program.  Please login to view the current issue and the full collection of past issues of the Blackfish Sounder