What might cause a biologist to spend three hopeful days on a paddleboard in the Saanich Inlet in the middle of winter? I’d heard rumour of a basking shark sighted in the area, and the slim possibility of seeing one sent me paddling out in the limited daylight. Although I returned from each search with numb toes and not even a glimpse of a dorsal fin, simply the potential of seeing an underwater giant had me buzzing with excitement for days.

These days, it’s extremely rare to catch a glimpse of a basking shark in British Columbian waters. Photo: Seán Molloy

Basking Sharks: A Cause for Excitement

Basking sharks are incredible marine animals that are rarely seen off the coast of British Columbia. They are the second largest fish on earth, growing to over 12 m long! When you think “shark,” you might think of rows of large, pointed teeth – but that description doesn’t apply here. Like humpback whales and manta rays, basking sharks are filter feeders, with large gill rakers that catch and sort the plankton they eat. They swim with their mouths open wide, bringing as much water (and plankton) as possible through gills that are so long, they nearly encircle their heads. They do have multiple rows of teeth, but each tooth is less than a centimeter long.

A basking shark feeds, mouth open to gather and filter plankton. Photo: Alexander Mustard

A Dark History

Fossils show that basking sharks have been swimming the oceans for over 29 million years, yet it took only a few short decades for the Canadian government and commercial fisheries to decimate the north Pacific population.

One hundred years ago, there were hundreds, or perhaps thousands, of basking sharks off the coast of British Columbia. In the mid-1900s these gentle giants were deigned an obstacle to commercial fisheries, due to sharks becoming entangled in fishing nets and damaging gear. Instead of addressing the fishing methods as the issue, the solution was a brutal and terribly effective eradication program led by the Canadian government. The methods of this cull were horrific: as basking sharks fed on plankton at the surface, they were sliced open by a long knife mounted to the bow of the Comox Post, a Canadian Fisheries department vessel. Additional Fisheries patrol vessels were instructed to kill basking sharks with blunt force by ramming them with their bows. Many members of the public held anti-shark mindsets at this time, and basking sharks were shot, harpooned, and otherwise harassed along the coast. At the same time, basking sharks were targeted by fisheries that harvested their massive, oil-rich livers. On top of it all, sharks continued to die by accidental entanglement in fishing gear.

Although government-led killings ceased in 1970, to this day there are only a few basking shark sightings per year off the coast of British Columbia.

A basking shark swims away. Photo: Scubography

Endangered and Unknown

As Joni Mitchell said, you don’t know what you’ve got ’til it’s gone. Several decades after spearheading the slaughter of this species, the Canadian government recognized the importance of basking sharks as a part of the coastal ecosystem. The Pacific population of basking sharks was designated as endangered in 2007, and Fisheries and Oceans Canada has been researching and monitoring the population to protect the few individuals left and assist in their recovery.  

Although the population of north Pacific basking sharks isn’t decreasing at this point, from what researchers can tell, it also hasn’t increased. Basking sharks grow slowly, have few babies, and can live for 50 years. Females are pregnant for between two and a half to three and a half years—the longest pregnancy of any animal with a backbone. These traits mean populations take a long time to recover.

Although eradication programs have long ended, basking sharks are still threatened by entanglement with fishing gear, harassment, and collisions with vessels.

Much about basking sharks remains a mystery to us, including their critical habitat in British Columbian waters. Reporting basking shark sightings to Fisheries and Oceans Canada’s Shark Research Lab (1-877-507-4275) aids in research on their habitat, abundance, and migration patterns. By learning more about these benign behemoths, we can better protect them and the areas they rely on to survive.

Further Reading

https://wildlife-species.canada.ca/species-risk-registry/virtual_sara/files/plans/Ap-BaskingPelerinPacFinal-v01-2020Feb-Eng.pdf.pdf

https://thetyee.ca/Books/2006/12/07/BaskingSharks/

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