Tagging White Sharks ...

Photo is of white shark and beach patrons with bright inflatable beach toys just West (what locals would refer to as North) of the Main Lifeguard Tower at Center Beach, Coronado.

Last Wednesday, my long-time swim buddy, James Murphy, and I went down to check out shark expert Dr. Chris Lowe and his graduate students who were working with Coronado Beach Lifeguards in front of the Main Lifeguard Tower after our morning ocean swim. Since the Spring, we had been hearing about white shark sightings from a wide variety of Coronado watermen from surfers and paddlers to instructors at Naval Special Warfare Center (BUD/S and SWCC) and Coronado Beach Lifeguards. In fact, we encountered two ourselves on our ocean swims one just south (actually east) of the Main Lifeguard Tower at Center Beach and a few days later in June just south (east) of the North Island Fence. At the popup tent in front of the Main Lifeguard Tower, we met with Lowe, his graduate students, Beach Lifeguard Captain, Sean Carey and Coronado Beach Lifeguards as well as our friend and fellow Coronado waterman, Steve Ogles. Lowe and his students were very knowledgeable about sharks and their behavior, which was extremely fascinating. They were also quite candid about what they knew, what they did not know and were trying to find out.

We watched the team of researchers and our Coronado Beach Lifeguards use a drone to spot the sharks and vector the two Coronado Lifeguard craft, a Rescue Water Craft and Inflatable Rescue Boat, to film and hopefully tag the sharks. What was surprising was not only the range of the animals during the morning from the North Island Fence to south (east) of the Main Lifeguard Tower and back several times; but how close the sharks were to beach patrons without their knowledge and how skittish the sharks actually were even at estimates of seven to eight feet (by the experts). Then at about 11:42 a.m., the team tagged the first white shark, a seven-foot female, right off Main Tower; what a thrill! Later as we watched from shore, we saw the team filming another animal and approach for tagging. Suddenly, we saw the triangular fin above the surface and tail boil the water and the shark was gone before the team was able to tag the animal, again very close to Main Tower. They wanted to film the shark first to further identify it by markings as well as determine the sex, (claspers means male, no claspers means female); because once the researcher places the tag, the animal is off like a rocket swimming fast and diving deep. The battery powered tags will last for about two years and have a feature if the animal stops moving for a few days (a sign of death), a buoyed portion will rise to the surface.

Lowe explained white sharks are 3.5 to 5 feet at birth and grow about a foot a year. These juveniles begin hunting immediately but their prey are mostly stingrays and halibut. This explains why I saw so few stingrays this summer during my swims and fewer people getting treated for stingray stings at Main Tower on my beach runs.

The juveniles are also very skittish and dolphins and sea lions will nip at them. Once the sharks are about 10 feet, about the 10 year mark for males and 12 year mark for females, their teeth begin to change from very pointed like puppies and kittens to become broader. They gain girth as the new adults’ hunting patterns change because they can now tackle sea lions and large seals (remember these pinnipeds are very strong and have sharp teeth.)

Lowe said they are trying to learn more about the sharks’ behavior and why they are at one beach for a time, then disappear and are at another beach. This is part of the tagging program. He also explained that the current buoy deployed at Coronado’s Central Beach is old technology that must be manually accessed and downloaded. This means that the data is not timely, but there are buoys available which operate with cell phone technology and can provide much more real time information about the sharks. These buoys also transmit local water conditions such as temperature and current direction every 60 seconds. It appears that when the temperature drops, the white sharks will move south. He said white sharks from Monterey Bay have been observed as far away as the Gulf of California in Mexico. These real time buoys would be a worthwhile investment for the City of Coronado and provide timely data streams for Lowe and his students as well as our Beach Lifeguards. Lowe explained that community education was paramount. He and his graduate students would be happy to get involved with an outreach program to help within our community, especially the children and their parents. There is a greater need for everyone to understand these fascinating animals and make informed decisions based on science not on fear.

Phil Garn is an avid year-round ocean swimmer. Since coming to Coronado in 1983 with the Navy, he has logged thousands of ocean miles and swum a variety of courses from the Coronado Rough Water to the English Channel as well as paddled, kayaked, surfed and dove.

(0) comments

Welcome to the discussion.

Keep it Clean. Please avoid obscene, vulgar, lewd, racist or sexually-oriented language.
PLEASE TURN OFF YOUR CAPS LOCK.
Don't Threaten. Threats of harming another person will not be tolerated.
Be Truthful. Don't knowingly lie about anyone or anything.
Be Nice. No racism, sexism or any sort of -ism that is degrading to another person.
Be Proactive. Use the 'Report' link on each comment to let us know of abusive posts.
Share with Us. We'd love to hear eyewitness accounts, the history behind an article.