Have you seen this shark

Have you seen this shark
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Have you seen this shark

Help us monitor the Pacific population of basking sharks

You can help

Keep a lookout for basking sharks when you’re on or near the Pacific Ocean, and report all sightings and incidents to DFO. Your information will help to determine population abundance and distribution.

How to identify a basking shark

First of all, they are big – up to 12 m (40 feet) in length. Look for gill slits that wrap almost entirely around the head, a pointed snout, a large mouth with minute teeth, a large dorsal fin, and a crescent-shaped caudal (tail) fin.

As a basking shark feeds open-mouthed near the surface, you can often see the tip of the snout, the dorsal fin, and the tip of the tail.

Be cautious. Take a photo.

If you see a basking shark and you are on the water, slow down to less than 5 knots and keep 100 m away. Take photographs or videos of your encounter for verification. Good quality photographs of dorsal fins and other distinguishing features (caudal fin, snout) can be used to identify species and even individuals.

Basking sharks are endangered

The basking shark is the second largest fish in the world (after the whale shark), reaching a length of up to 12 m (40 ft).

Basking sharks are filter-feeding giants that primarily eat zooplankton. They can be spotted at the surface in areas of high plankton concentrations, such as fronts where water masses meet, headlands, and around islands and bays with strong tidal flow. With their enormous mouths wide open, they sweep through the clouds of microscopic animals, gathering them up like a sieve.

At one time, there was an abundant Pacific population of these large, peaceful sharks. However, since the 1940s the rate of decline has exceeded 90 per cent.

This dramatic decline is primarily due to a fishery for liver oil (1941-47) as well as an eradication program (1955-1969) which was carried out because of a conflict with commercial fishing. The species is also particularly vulnerable because it has a low rate of reproduction.

What are we doing about this decline

In 2010 the Pacific population of basking sharks was listed as ‘Endangered’ under Canada’s Species at Risk Act (SARA), offering them legal protection. Fisheries and Oceans Canada (DFO) is leading the recovery process for this population with a variety of initiatives.

Recovery strategy and action plan

In 2011, DFO outlined in a Recovery Strategy what needs to be done to arrest or reverse the decline of this species. The Recovery Strategy includes: an assessment of the threats; population and distribution objectives; broad recovery approaches; and a schedule of studies to identify critical habitat. An Action Plan developed in 2020 outlines specific recovery measures to be undertaken by DFO and others to address the threats and achieve the population and distribution objectives

Ongoing research

Collecting data is key to knowing how the population is faring and to learning more about this fascinating shark. Methods for studying basking sharks focus on both individuals and their habitats, and include bio-sampling of live and dead sharks; genetic analyses; tagging for satellite monitoring; boat-based and aerial surveys; habitat modeling; and satellite detection. DFO is also sharing information with researchers worldwide to help us all fill gaps in our knowledge of population structure, abundance, seasonal distribution, and critical habitat.

What we know about basking sharks

Basking sharks live to about age 50. They have a late age of maturity of 12 to 16 years old for males and 16 to 20 years old for females. Females may be pregnant for 30 to 42 months – the longest gestation of any vertebrate! The timing between litters is two to four years, and the litters are small with only five or six pups.

Basking sharks appear infrequently in Canadian Pacific waters. The population size is unknown, but is estimated to be between 321 to 535 individuals.

The Pacific population ranges from Alaska, USA to Baja California, Mexico, and is believed to winter off California. Basking sharks are typically present in Canadian Pacific waters from May to September. There have been recent sightings off Haida Gwaii, the Central Coast, the West Coast of Vancouver Island, and in the Salish Sea.

Calanoid copepods (zooplankton) are a favourite food.

From a boat, the distinctive large gill slits are clearly visible as the shark cruises near the surface.

42 confirmed or reliable sightings in Canadian pacific waters since 1996 (as of May 2021)

To report your sightings or incidents

Go to our website and use our online form

Contact us directly at:

Basking Shark Sightings
Pacific Biological Station
Nanaimo, BC V9T 6N7

Toll-free: 1-877-50-SHARK (1-877-507-4275)
E-Mail: sharks@dfo-mpo.gc.ca

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