The mysterious basking shark

Basking sharks feeding with their gaping mouth were once a common sight in the Salish Sea, according to Romney McPhie, Recovery Planner and Senior Biologist with the Canadian Department of Fisheries and Oceans Species at Risk Program. The gentle giants are rarely, if ever seen, today.

“The sharks could return to the Salish Sea,” McPhie said, should recovery efforts prove successful. McPhie will be discussing the sharks on Aug. 10 at 7 p.m. at a free Zoom lecture as part of the Whale Museum’s summer lecture series. McPhie said she will be touching on the Basking shark’s remarkable biology, humans’ historical relationship with the animal, its current status, and what be done as a society to help the shark recover.

“Basking sharks used to be extremely common in our waters in the early to mid-20th century, including in inner coastal waters of the Salish Sea,” McPhie said. “However, due to “undesirable” interactions with the salmon fishing fleet, DFO launched an eradication program in the 1960s which – along with a number of other human activities (commercial harvest, incidental catch, sport harpooning) – reduced their numbers dramatically.”

Historically, McPhie continued, Basking sharks were horribly maligned by the media as ‘great brutes’ and salmon-killing monsters. “We now understand that Basking Sharks are truly gentle giants,” McPhie said.

As a result, Basking sharks are now extremely rare on the Pacific Northwest coast. Due to the shark’s slow life history, including their late age at maturity, low fecundity and long gestation period, even if human-caused mortality is zero, the road toward regaining population previous numbers will be long.

McPhie began studying Basking sharks as a Research Biologist with Fisheries and Oceans Canada in 2009. She was responsible for researching and assessing elasmobranchs, which include sharks, skates, and rays, as well as other marine fish species in the Canadian Pacific waters to support stock management and conservation objectives. The Basking Shark was listed as endangered under Canada’s Species at Risk Act in 2010.

“For any species listed as endangered, threatened, or extirpated under SARA, a recovery strategy and action plan(s) are needed, ” McPhie explained. In 2011, a recovery strategy was developed for Basking sharks, and an action plan was developed in 2020. To view both, visit Canada’s Species at Risk Public Registry at https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry.html.

Basking sharks are the second largest fish in the world, after the better-known whale shark (Rhincodon typus), reaching lengths of 10-12 m. Despite their size, these sharks are still able to jump out of the water.

These leviathans are one of only three filter-feeding sharks and the only filter-feeding sharks in local waters. The other two species that filter-feed are the whale shark and the megamouth shark (Megachasma pelagios). They use modified gill rakers to capture zooplankton from the water.

Although filter-feeders, Basking sharks have tiny teeth. The only time they use these teeth, McPhie said, is likely in the uterus, where unborn Basking sharks are nourished by consuming unfertilized eggs. This is called “oophagy”, and is practiced by a number of well-known species including white sharks, thresher sharks, and mako sharks.

Another interesting fact, no one has ever witnessed Basking sharks mate.

“Possible courtship behavior – groups of sharks swimming nose to tail – has been observed in other areas of the world, but as far as I know, mating has not been observed,” McPhie said

Basking sharks play a vital role in the environment by consuming extremely large quantities of zooplankton, similar to large whale species. As such, like whales, they are likely recycling (or distributing) nutrients and enhancing primary productivity in areas where they feed. They are also likely prey to other predators like killer whales (e.g., the offshore ecotype).

The largest current threats to the Basking shark are entanglement, collision with vessels, harassment from marine-based activities, and prey availability, according to The recovery SARA recovery strategy and action plan.

Learning more about these sharks is one key objective, McPhie said. To better inform recovery actions moving forward. Increased public awareness can help increase our collective knowledge, and reduce threats.

“We are asking anyone who is out on the water who spots a Basking Shark to report it to DFO,” McPhie said.

Sightings can be reported in the following ways:

Toll-free: 1-877-50-SHARK (1-877-507-4275)

Email: sharks@dfo-mpo.gc.ca

More information on the DFO Shark Sightings Network can be found here: https://www.dfo-mpo.gc.ca/species-especes/sharks/report-eng.html

The Pacific Sharks Research Center, in Moss Landing, CA, also has a “Spot a Basking Shark” Project: https://mlml.sjsu.edu/psrc/citizen-science/spot-a-basking-shark/

When asked if there is anything she hopes attendees take away from her talk, she said, “Coming away from this presentation, I am hoping that people are as amazed and intrigued and enthusiastic about the Basking Shark as I am!”

McPhie added that she hopes people realize society made huge mistakes when with the Basking Shark. “If we can learn from these mistakes and move forward guided by a commitment to conservation. These creatures have an intrinsic right to exist in our waters, and we have a responsibility to help bring them back,” McPhie said, adding “If you spot a Basking shark, go out and buy a lottery ticket, ‘cause you’re one of the lucky ones!”

Go to https://us02web.zoom.us/j/86896003899 to join the Aug. 10 Zoom meeting.