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A day in the life of a basking shark

Basking Shark


Have you ever stopped to think about your daily routine? Maybe you start your day with a big breakfast, or a jog through the neighborhood.  Most sharks have routines, too.  But a basking shark’s day is anything but ordinary.

When the Southwest Fisheries Science Center first initiated a study on basking sharks off the coast of California a year ago, they were not sure what they would find.

“The basking shark was recently listed as a Species of Concern by NOAA,” said Heidi Dewar, a fisheries research biologist for the NOAA Southwest Fisheries Science Center. “These sharks are rarely seen, but physically tagging them with a satellite device was one of the key parts of the study. We knew it would be a challenge.”

Tagging sharks with satellite technology allows scientists to track their

movements and determine how oceanography influences where basking sharks go and what they do. In the spring of 2010, 11 basking sharks were

spotted off the coast of San Diego, California. Three have been tagged this year, the first basking sharks ever tagged in the Pacific Ocean. 

Nine days after one of the sharks was tagged, the tag fell off and was recovered on a San Diego area beach.  The tag provided scientists with a detailed look at the way this basking shark used its environment. What NOAA scientists found is that the shark does not rely on daylight versus night to shape its behavioral patterns, as with most other sharks. The picture (bottom right) of one day’s worth of data from the tag revealed that the basking shark dove more than 50 times to depths up to 160 feet.

“Based on other research, we knew that basking sharks were unpredictable, but we had yet to confirm this for the Pacific Ocean,” said Dewar. “Having this

Basking Sharks routine graphClick on the graph to view full size.

information helps us to characterize their Pacific habitat and we can better understand trends in population.”

Synchronized swimming

The reasons this shark dipped and dove so much may have everything to do with food. Basking sharks eat mainly plankton and they have a particular love for copepods (pictured right) that are carried by ocean currents. To keep up with the shifts in copepods, basking sharks shift their behavior, too.

Copepods are far more complex than their size would suggest. They will actually change their behavior if they sense that too many of their neighboring copepods are being eaten. If the basking sharks want to eat, they must adjust to keep up with their prey.

Scientists need your help

It is hard to believe that scientists need help finding one of the largest fish in


the ocean. But so few basking sharks remain in the waters off California that researchers are hoping the general public can assist by reporting any sightings.  Scientists will then tag and track these animals to learn more about their behavior and distribution. 

If you see a basking shark while you are on the water, please call (760) 408-7726 or (619) 743-9004. If you wish to report a sighting after you have returned to land, please provide the date, time, and location of the sighting at either (858) 334-2884 (Southern California) or (831) 771-4438(Central California, north of Morro Bay). You can also email us at Photos or video are appreciated.

For more information see: The previous link is a link to Non-Federal government web site. Click to review NOAA Fisheries disclaimer   The previous link is a link to Non-Federal government web site. Click to review NOAA Fisheries disclaimer previous link is a link to Non-Federal government web site. Click to review NOAA Fisheries disclaimer

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