Basking shark

 Cetorhinus maximus

Basking shark (Cetorhinus maximus). Photo credit Gregory B. Skomal.

Distribution: Occurs in temperate and boreal waters from the Gulf of Alaska to Gulf of California. A small fishery took place off Monterey Bay between 1924-1950s for fish meal and liver oil; it is still taken as bycatch in the area, although it has not been observed in the CA/OR driftnet fishery. Highly migratory and noteworthy for its seasonal appearance in certain localities and subsequent disappearance. In the eastern Pacific occurs in greatest numbers during autumn and winter off California, but may shift to northern latitudes in spring and summer, along Washington and British Columbia.

Growth and Development:  Litters of about 6 pups, generally born 150-170 cm total length. Basking sharks are one of the largest fish in the sea, second only to whale sharks, and they can reach a maximum size of 45 feet (Miller and Lea 1972) and reach maturity at 570 cm for males and 800 cm females. They are distinguished from whale sharks by their pointy snouts, dark grey to brown color, and gill slits that nearly encircle their head, and they have a huge liver which provides buoyancy, although basking sharks may leap out of the water.

Feeding: Like whale sharks, as well as all of the largest rays and cetaceans, basking sharks are filter feeders foraging near the base of the food-web on krill and other zooplankton. They are often seen skimming the surface in large aggregations, and consequently they have no interest in divers, surfers or swimmers. In winter, they will feed on deep-water plankton concentrations.

Conservation and Management: In response to the apparent decline in local populations, NOAA recently listed the basking shark as a “Species of Concern”. Some reasons for this listing are the apparent reduction in numbers, the lack of a recovery in population size despite around 50 years without being targeted and lack of information on very basic aspects of their biology. For example, we currently don’t know how old basking sharks are when they first reproduce, where they have their young, what the range of their movements are or the structure of their populations. Collecting this type of information will help us to understand how both the environment and human activities influence basking shark numbers as well as aid in the development of a recovery plan for basking sharks off the West Coast of North America. In the mid 1900’s basking sharks were targeted by fisheries or eradication programs that killed a large numbers of individuals. While historically animals were reported in the hundreds and thousands, more recently only a few individuals have been seen in any given year.  

Learn more about the basking shark as a Species of Concern in our detailed fact sheet.



Basking Shark Tagging Research

Basking shark satellite tag 

The Southwest Fisheries Science Center  initiated a study on basking shark off the West Coast to use satellite technology to track the movements of basking sharks and determine how oceanography influences where they go and what they do. The satellite tags will record temperature and depth throughout the track allowing us to look at habitat use. To determine the shark’s locations the tag will both link to GPS satellites when it is at the surface and record light levels which will allow us to estimate latitude and longitude. SWFSC used this Wildlife Computers MK10-PAT, Fast-GPS tag in the study. The tag is attached just below the dorsal fin on the back of the shark and the leader extends away from the shark's body, allowing the tag to float along beside it. When the shark is swimming at the surface, the antenna should break the water's surface and communicate with satellites.




tagging flagJune 6, 2010: NOAA Fisheries Tags the First Basking Shark in the Pacific Ocean

On Sunday, June 6th, 2010, eight miles offshore from San Diego, California, Dr. John Hyde, the supervisor of FRD's Molecular Genetics program, and Owyn Snodgrass, a member of the FRD Large Pelagics Program, successfully tagged a basking shark, the first time this has been done in the Pacific Ocean. Satellite technology will be used to track the movements of basking sharks and determine how oceanography influences where they go and what they do. The tags will record temperature and depth throughout the track allowing us to look at habitat use. To determine the shark’s locations the tag will both link to GPS satellites when it is at the surface and record light levels which will allow us to estimate latitude and longitude.



tagging flagMay 15, 2011: NOAA Fisheries Tags Two More Basking Sharks in the Pacific Ocean

Basking sharks (Cetorhinus maximus) have shown up once again off the coast of Southern California and sportfishermen and private boaters are reporting sightings from Carlsbad to the U.S./Mexico border. On Sunday, May 15, 2011, Dr. John Hyde and Owyn Snodgrass, both members of the FRD Large Pelagics Program, successfully tagged a 20-foot long basking shark four miles off Torrey Pines State beach. The Mk10-AF Transmitting Fast-GPS Tag made by Wildlife Computers (pictured above) is designed to record depth, temperature, and location data. This was the second basking shark tagged in the Pacific Ocean. Unfortunately the tag popped off prematurely and was found on the beach by a surfer in Mission Bay. Regardless of the premature release, the tag still recorded lots of valuable data giving scientists an opportunity to learn more about these mysterious sharks and why they are being seen off the coast of San Diego. Sightings have continued into the month of June and a third tag was deployed by John Hyde and Owyn Snodgrass on June 7th, 2011, five miles off Point Loma. NOAA biologists hope this third tag will stay on the shark for up to 8 months recording its movements and habits.

Watch a video of the second tagging effort.


tagging flagBasking Shark Tag surfaced in February 2012 

Basking sharks used to be abundant off the West Coast but numbers appear to have declined starting in the mid 1900's. In order to develop a recovery plan the U.S. has teamed up with Mexico and Canada to collect basic biological data on basking shark. One goal of that program is to place satellite tags on basking sharks to look at large scale movements. Three sharks have been tagged since 2010.On February 2nd, 2012, one of the satellite-based tracking devices outfitted last year resurfaced near Hawaii after eight months collecting data on the migration of the Basking shark. The San Diego Union Tribune published an article on February 13th that detailed the importance of such an event. The piece, entitled "Shark's journey a first for science,"The previous link is a link to Non-Federal government web site. Click to review NOAA Fisheries Disclaimerfeatured an interview with Heidi Dewar of SWFSC. This is the first demonstration of a link between Basking Sharks in the Eastern and Central Pacific. 


How you can help!

If you see a basking shark while you are on the water and can call from your vessel, please call:

John Hyde at (760) 408-7726 or Heidi Dewar at (858) 546-7023.

If you wish to report a sighting after you have returned to land please provide the date, time and location of the sighting, as well as any comments to (858) 334-2884 or send an email to Heidi.Dewar@noaa.gov.

Any photos or video would also be appreciated and can be sent to:
Heidi Dewar
NOAA Fisheries, SWFSC
8901 La Jolla Shores Dr.
La Jolla, CA 92037

Last modified: 12/8/2015