DEL MAR — Early Friday morning, student researchers Patrick Rex and Lauren Faulkner donned Neoprene wetsuits and 30-pound scuba tanks, preparing to depart from Del Mar Lifeguard headquarters into the ocean water to gather data on their research subjects — sharks.
Rex and Faulkner, part of a team of graduate students with the Shark Lab at California State University Long Beach, are studying the relatively new local aggregation of juvenile white sharks, which first appeared in Del Mar in 2019 and has moved slightly south toward Torrey Pines State Beach in recent months.
Under the leadership of Shark Lab director Dr. Chris Lowe, the team has tagged just over 200 animals in the aggregation, including around 65 just in the past year, on bi-weekly trips down to Del Mar.
This past weekend, Rex and Faulkner dived down to retrieve electronic receivers, which log each instance that a tagged shark swims nearby, download the data on a lifeboat, and then dive back down to return the receiver to its spot.
“They’re giant ears listening to see if sharks are around,” Rex said, describing the receivers. “What we’ve found is that the sharks are very close to shore — within 100 yards is where they spend 50% to 75% of their time during the day.”
The juveniles, those under 9 or 10 feet in length, are believed to be drawn to the area’s warm, shallow waters, which provide safety from large predators, and end up staying because of the food sources, said Lowe.
However, sharks usually don’t stay in this region for long, and the lab is working to determine what makes this area a hot spot.
“If they’re gonna spend a ton of time there, they have to be eating,” Lowe said. “We know they’re eating stingrays, and those rocky reefs have quite a few fish associated with them. I think that’s the reason why they stay, and the reasons they go there, to begin with, are for warm water and safety.”
Of course, these warm waters are also enjoyed by many swimmers, surfers and paddle-boarders throughout the year. Drone footage captured by the lab has determined that each day at the beaches of Del Mar and Torrey Pines State Park, at least one swimmer or surfer is enjoying the water in close proximity to a young white shark.
Tagging the sharks themselves is a process that takes under a minute to do, depending on the shark’s temperament. A member of the Shark Lab team will locate a shark using a drone, while others approach the shark in a lifeboat and insert the tracker tag just below its dorsal fin using a long metal pole.
Faulkner said the process is briefly uncomfortable for the shark but does not cause lasting harm. It’s not unlike the pain of an ear piercing, especially since their bodies are primarily cartilaginous.
“The tags, I like to think of as a little earring,” Faulkner said.
The tags then “ping” off the signal of the dozens of Bluetooth receivers placed both inshore and offshore, allowing researchers to see how often specific sharks — with names in the database like “WS-22-44” identifying the 44th shark tagged in 2022 — are in the area.
Some sharks have “pinged” over 100 times, indicating that they spend a lot of time swimming back and forth along Del Mar’s beaches. Others have only been detected a handful of times, which could mean they are not spending much time in the area.
According to Lowe, the aggregation does not comprise a fixed number of the same sharks but includes sharks frequently coming and going. At this point, Lowe expects this aggregation to remain in the area through the winter.
Sharks making headlines
While these sharks mostly lie under the radar on a daily basis, they have made headlines in San Diego County in recent weeks. In late October, an 8-foot-long shark killed by fishing equipment washed ashore in Torrey Pines, and a swimmer in Del Mar suffered a nonfatal bite, believed to be from a juvenile great white, just days later on Nov. 4.
The Shark Lab has been involved in responding to both incidents. Working closely with the California Department of Fish and Wildlife, the lab is testing DNA from the bite wound to determine whether it was a white shark and, if so, what size.
The individual, Lyn Jutronich, was around 200 yards from shore near 17th Street when she saw a shark clamp onto her thigh, shake her once, and then release her and swim away, she described to KGTV. Jutronich was able to make it back to shore with her swim partner and receive treatment at a hospital.
Lowe hypothesizes that this may have been an “investigatory bite” by a juvenile white shark, which could have mistaken Jutronich for a sea lion. He does not think it likely that the shark was acting out of aggression due to having its space invaded since they have seen humans and sharks coexisting close by in the waters for years.
“That leads me to think a shark made a mistake, and we don’t see that too often,” Lowe said. “Obviously, these things are disconcerting, and we never want to see anybody hurt by a wild animal, but our data shows that people and sharks are interacting daily in these areas — literally every single day, and sometimes dozens of times a day. When you think about the fact that this is the first bite with this aggregation … that’s pretty remarkable.”
Rex noted that the bite earlier this month was the first in Southern California since 2018. Despite the rarity of these events, many people believe that sharks are a constant danger, something the lab tries to dispel through education efforts.
Over the summer, the lab held “Shark Shacks” at local beaches throughout Southern California, including several throughout San Diego County, where the public could learn about these marine animals.
Over time, Rex said, they have seen community members become more receptive to the aggregation and appreciate them as they do other types of local wildlife.
“What we do in the lab is a lot of outreach … we try to bring education to the beaches,” said Rex. “It’s a lot of work, but it’s very rewarding too, and it’s been interesting seeing the changes in the community.”
More significant than the threat of sharks to humans, Rex said, is the danger of humans to the local sharks due to targeted fishing practices. Since the aggregation has appeared, several sharks have been discovered trailing large hooks and long fishing lines, which can eventually kill them.
“Within one week of us finding that aggregation, 40% [of the sharks] had signs of fishing injury,” Lowe said.
Currently, it is difficult to hold fishermen using this equipment accountable since they can claim they were not deliberately targeting white sharks.
However, a new state law is set to take effect at the beginning of 2023, which will prohibit anglers from using shark bait, lures or chum to attract white sharks or use them within one nautical mile of a shoreline where white sharks are known to be present.