Researchers weigh pros and cons of west coast seal cull

By Ian Holmes
August 15, 2018 - 5:34pm

A harbour seal making an appearance on Nanaimo's waterfront. Ongoing research is studying the impact seals play in the Strait of Georgia ecosystem.Kathryn Seymour

NANAIMO — Preliminary results of a study have revealed new information about seals in the Strait of Georgia, which have long been blamed for high mortality rates in west coast salmon.

The Department of Fisheries and Oceans, Pacific Salmon Foundation and University of British Columbia are the key players in an ongoing study tracking how the estimated 35,000 harbour seals in the Strait fit into the ecosystem.

Andrew Thomson, the DFO's regional director for fisheries management, said while seals undoubtedly feast on salmon, research from a variety of sources, including fecal samples, showed salmon make up less than 10 per cent of seals' overall diets.

“It becomes a bit more of a complicated story of what the interaction is of seals on salmon populations,” Thomson said. “They certainly are consuming salmon, but they may also be consuming predators of salmon, so what is the end result?”

Thomson told NanaimoNewsNOW seals in fact primarily eat hake, a fish that preys on salmon, while herring are another staple of their diet.

He said talk of a west coast seal cull has been floated around for many years, but following through on the idea could have unintended consequences.

“Seals are a prey item of transient killer whales, which is of importance to the department to ensure there is a food source for those transients,” Thomson said.

He said the research, based out of the DFO's Pacific Biological Station in Nanaimo, has been ongoing for three-to-four years. Thomson said it's unclear when the work would be complete and findings published.

He said tagging salmon with acoustic tracking devices is intended to offer more certainty on the volume of salmon seals eat.

Dr. Brian Riddell, president and CEO of the Pacific Salmon Foundation, said the research showed seals are skilled hunters who feed effectively in estuaries. He said a concerning feeding habit of seals is the amount of young salmon they consume.

“Approximately 30 per cent of the juvenile Chinook and Coho in the Strait heading out to sea are falling victim to harbour seals,” Riddell said. “That's a significant concern since it's a substantial marine mortality caused by just one predator.”

Riddell said decades ago it was fair game to shoot harbour seals in the Strait, with population numbers around the 7,000 mark in the early 1970s.

While much larger California sea lions also have a presence in local waters, Riddell said they appear to be less prevalent and don't feed on juvenile salmon.

Riddell said if a seal cull is deemed to be a necessary step forward it would have to be done consistently to make a notable impact.

“This is an ongoing program, this is not a one-time event. It requires a commitment of time, effort and planning.”

The First Nations group Aboriginal Equity Partners is among several stakeholders calling on the federal government to implement a seal cull in the Strait of Georgia.


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