Incident Leads to Heightened Concern About White Sharks in California
2021 was a relatively active year for shark attacks along the west coast of North America, with five confirmed white shark encounters and one fatality. The most recent incident occurred at Morro Strand on December 24, 2021. 31 year old Thomas Butterfield was discovered by beach walkers face-down and pronounced dead at around 1030 AM. The nature and size of the injury described by emergency responders indicate it was a white shark attack. The shark was later estimated to be 16 feet long by California Department of Fish and Wildlife.
Since 1950, there have been 203 shark incidents* in California involving all species of sharks, at least 180 of which involved white sharks. Of those, 15 were fatal and all of the fatalities involved white sharks.
The previous serious white encounter in California occurred October 3rd, 2021 on a surfer at Salmon Creek State Beach in Sonoma County CA.The man was bitten in the thigh while surfing with friends at Salmon Creek Beach Sunday morning. Fellow surfers helped him to safety before first responders took the surfer, in his 30s, to a nearby hospital. The man identified only as Eric was observed thrashing and struggling and calling for help as other surfers paddled over. The surfers quickly applied a tourniquet from a surfboard leash and helped the victim ashore. He was airlifted to a Santa Rosa hospital where his injuries to his legs are considered serious but he survived.
Salmon Creek is one of the known hot spots for white shark encounters with surfers.
On May 9, 2020, 26 year-old surfer Ben Kelly died from an arterial wound at Manresa Beach near Santa Cruz California resulting from a shark attack. Although not directly identified, given the nature and severity of the wounds, in all probability the species responsible was a white shark (Carcharodon carcharias). Although other species of large shark such as blue shark, salmon sharks and thresher sharks visit this coastal region, they generally avoid humans. White sharks are the most commonly encountered large shark species by humans off the west coast.
Most of the encounters with white sharks along the west coast of North America occur with mature white sharks in the months between August and November. These months we call Sharktober are when the large white sharks return to the coast after an annual migration to forage on seals and sea lions.
Protected in California since 1993, more sightings and close encounters with young sharks are occurring in Southern California. However, actual shark encounters involving bumps and bites are uncommon. According to the of California Department of Fish and Wildlife (CADFW), 190 shark-human encounters have been recorded in state waters between 1950 and 2020. Mr. Kelly makes the 191st incident and the 14th shark related fatality recorded in that period for California.
Since 2000, the California Department of Fish and Wildlife has recorded an average of 1.8 encounters (bite or bump) involving sharks per year, with one fatality every five years. Most encounters do not involve an injury and are considered investigations by the shark.California Department of Fish and Wildlife
White sharks, also called great white sharks (Carcharodon carcharias), are intriguing to many, and a fact of life to ocean goers off the west coast of North America.
According to the Global Shark Attack File conducted by Dr. Ralph Collier of the Shark Research Institute, the last fatality in California before Mr. Kelly occurred in 2012 on surfer Francisco Javier Solario Jr. at Surf Beach near Point Concepcion. That fatality followed another 2 years earlier experienced by a white shark on 19 year-old body boarder Lucas Ransom, also at Surf Beach. Prior to that, the last recorded fatality was triathlete Dave Martin, killed while swimming off Solana Beach, San Diego in 2008.
Previous to that, the last serious incident with a white shark and a human occurred in 2018. Thirteen year old Keane Webre- Hayes was bit by an 11 foot white shark while diving for lobster off Encinitas, San Diego. Keane was released by the shark and rescued, and resumed his ocean activities less than a year later. Two other anomalous incidents occurred with a sub-adult white sharks biting Triathlete Maria Korcmaros while swimming off Corona del Mar Beach in 2016, the first recorded in Orange County. A year later the second event in Orange County occurred while Leanne Ericson was body boarding off San Onofre Beach in 2017. Both women survived and recovered with serious injuries. Together with Keane and marathon swimmer Steven Robles (bitten off Manhattan Beach in 2016), all have joined in support of shark conservation. Hosted by Orange County Register journalist and shark writer Laylan Connelly, the four held a reunion in 2019.
Professor Chris Lowe of California State University Long Beach has specialized in studying the white shark population in Southern California and Mexico. Dr. Lowe’s Shark Lab and Stanford Biologists from the Tagging of Pelagic Predators (TOPP) have documented the recovery and movements of these sharks in the Northeast Pacific. White sharks are birthed, or “pupped” in the summer months off Southern California and Baja. These juveniles and young of year sharks frequent warmer shallow waters off the waters between San Diego and Santa Barbara counties and feed on sting rays and other fish.
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Historically, the Northeast Pacific population of white has been overfished commercially and recreationally, and killed in a backlash to the movie Jaws. Shark fishing tournament’s occurred along the coast including in the San Francisco Bay, gill-nets set for swordfish drowned hundreds of juveniles and adult females in Southern California and a commercial fishery at the Farallon Islands nearly wiped out the adult population. In addition to increase legal protection from killing, populations of prey food has increased since protection in 1972 under the Marine Mammal Protection Act. Marine mammals populations such as California Gray Whales have been on the rise, including white shark’s favorite food: the Northern elephant seals.
Protection of shark food and the sharks themselves in 1993 has led to an increasing population, but estimates of the total size vary. A 2011 study by Chapple et. al. estimated the population of sub -adults and adult white sharks in the Central California Assemblage (which includes Guadalupe Island Baja), at only 219 individuals. The authors predicted that the entire adult and subadult population might be around twice that. Another study that included young and juvenile sharks estimated the total population to be greater than 1500 in the Northeast Pacific between British Columbia and Baja California, Mexico. It is believed that most of this population are Young of Year, juveniles and sub-adults.
Southern California serves as the birthing ground and nursing area for young white sharks which consume fish including stingrays. Sub-adults in the ten to twelve foot range transfer their diet to seals and sea lions which have more calories. Eventually these sub-adult sharks head north of Point Conception where seal colonies are more common.
Mature adults undergo a large offshore migration, leaving the favored feeding grounds where seals and sea lions breed such as the Farallon Islands, to an area in the mid N. Pacific east of Hawaii. Called the white shark cafe, the adult sharks are likely feeding on marine mammals and giant squid, and possibly mating. In the late summer and early fall, these sharks come back to forage along the west coast. This is the period of peak human interactions during the months we call Sharktober.
In general white shark’s prefer a temperature between 54 and 75 degrees Fahrenheit, with the adults tolerating colder waters. More sensitive to colder water, young shark typically migrate to water temperatures in the mid to high 60s and 70s F. In 2015 – 2016 a trend of unusually warm waters off the west coast was generated by a high sea surface temperature phenomenon known as “the Blob” followed by an El Niño. Dr. Lowe’s work indicates the sharks that would normally migrate south stayed in the Southern California bight over winter. Attracted by the warmer temperatures, young sharks living in Southern California also traveled north of Point Conception.
This warm water event led to younger sharks inhabiting Monterey Bay and frequenting the area around Santa Cruz, near the site where the most recent incident on Ben Kelly occurred. Current trends in sea surface temperatures are leading to predictions that another cycle of warm water may be developing off the west coast. Whether this will be associated with an increase in white shark encounters in 2020 remains to be seen.
Excluding the last few decades, data on shark attacks was difficult to acquire and was inconsistent. Even the sharks were misidentified in many encounters. Research and follow up of attacks by Dr. Ralph Collier of the Shark Research Committee, Dr. McCosker of the California Academy of Sciences, and Dr. Lowe, as well as staff from the California Department of Fish and Wildlife, has led to more careful investigation and documentation on shark attacks and human interactions since the 1970s. Statistics on species and victim behavior along the west coast of North America are probably the best available in the world. Although data collection methodology and statistical evaluations vary between the SRC and the California Department of Fish and Wildlife (CADFW), the department has published detailed reports on California shark attacks.
Risk by Activity
Of the 105 attacks (among all shark species) that have been reported by the CA Department of Fish and Wildlife since 2000, the largest group of victims were surfers, with 64 incidents, compared to 17 kayakers. Eight of the victims were swimmers, six were divers, and another six were paddleboarders. The remainder were an outrigger canoe, windsurfers, fishers, and boogie boarders. These incidents are all considered unprovoked. However, kayakers as second largest and growing category, were participating in fishing, or had bait or fish onboard which offers an additional attractant and could be argued are at least partially provoked.
The use of drones and social media have increased our awareness of sharks swimming off the California coastline, but a Stanford study published in 2015 indicates the risk of a shark attack off the west coast has decreased significantly.
Shark Inhabited Waters
Although white shark sightings have been higher in recent years, the number and risk of aggressive encounters is still very low. The Stanford study, published in Frontiers in Ecology and the Environment in 2017, finds that despite increasing records of shark attacks, mostly by white sharks in California, the individual attack risk has dropped by more than 91 percent during the past six decades.
Risk of Encounter by Activity
A 2015 Stanford study indicates that in the highest risk group, surfers, have a 1-in-17 million chance of being bitten by a white shark in California.Francesco Ferretti et al Frontiers in Ecology and the Environment
The study determined that the risk by other ocean activities include:
- Scuba divers are 6,897 times more likely to be hospitalized for diving-related decompression sickness than for white shark bites.
- Ocean-goers are 1,817 times more likely to drown than die from a shark attack.
- Scuba divers have a 1-in-136 million chance of being bitten.
- Surfers have a 1-in-17 million chance of being bitten.
Over 80% of recorded shark fatalities along the west coast are north of Point Conception.
Surfers, swimmers and divers in the region called the Red Triangle have the highest risk of an encounter with a white shark. Over 1/3 of all white shark attacks along our coastline have been recorded in the region bounded between Big Sur to the south, the Farallon Islands to the west and Point Arena to the North. The odds of an encounter with a large white shark are higher in the months we call Sharktober, between September and November when the large adults return from their migration to feed on marine mammals nearshore.
Besides trading in the surf board for golf clubs, surfers can reduce their risk by choosing when and where they surf. The best way to avoid a shark encounter is to avoid locations and seasons where risk is highest, the study’s authors advise. For example, the riskiest time and place for California surfers is October and November in Mendocino County. That risk can be reduced 25-fold if you surf in March, and more than 1,600-fold if you surf in March between San Diego and Los Angeles.
Co-existing with sharks
White sharks are increasing off our coastline, and scientists believe that is a good thing since it is a sign of ecosystem recovery.
Sharks play a vital role in marine ecosystems, and benefit prey populations and even humans by increasing ecosystem health. There is hope that through increased awareness, better data and warning systems we will minimize shark encounters. Individuals can also take responsibility to reduce a shark encounter. Shark Stewards has developed suggestions that west coast beach goers can take so both humans and sharks can swim unharmed.
How to Reduce Your Risk of a White Shark Encounter
Shark encounters and fatalities vary by activity, but there are steps we can take to avoid becoming a victim to a shark attack.
Report a Sighting: Shark Watch
See a shark? Add to the observation database by send out a tweet or instagram tagging SharkStewards and #SharkWatch. We will record the observation and share.
A first estimate of white shark, Carcharodon carcharias, abundance off Central CaliforniaTaylor K. Chapple, Salvador J. Jorgensen, Scot D. Anderson, Paul E. Kanive, A. Peter Klimley, Louis W. Botsford, Barbara A. BlockBiol Lett. 2011 Aug 23; 7(4): 581–583. Published online 2011 Mar 9. doi: 10.1098/rsbl.2011.0124PMCID: PMC3130246
Burgess GH, Bruce BD, Cailliet GM, Goldman KJ, Grubbs RD, Lowe CG, et al. (2014) A Re-Evaluation of the Size of the White Shark (Carcharodon carcharias) Population off California, USA. PLoS ONE 9(6): e98078. https://doi.org/10.1371/journal.pone.0098078
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