Great White Shark Duke at Tomales Point in 2011

This great white shark, nicknamed “Duke,” was spotted at Tomales Point in 2011. It was a massive 17-foot animal with the distinctive fin markings that allow researchers to tell one from another. Photo courtesy Paul Kanive

The great white shark population off Northern California's coast is healthy and growing, researchers say. Such conclusions were drawn from a study that occurred, in part, off of the Coastside.

Researchers from the Monterey Bay Aquarium, Stanford’s Hopkins Marine Station and Montana State University tracked sharks in “the red triangle,” a swath of sea stretching between Monterey Bay, the Farallon Islands and Bodega Bay, known for having a high concentration of white sharks.

To estimate population size, researchers put a small amount of seal meat in the water to create a scent, then use a seal-shaped decoy to attract white sharks. They photograph the sharks, track and identify each of them through differences in the shark’s dorsal fin.

“Fin patterns are like a fingerprint, and some of these sharks we know so well we can identify them immediately when they come to the surface,” said Paul Kanive, a marine ecologist with Montana State University and lead author of the study.

Using this method, the research team identified 266 adult and young great whites in 2018, an increase from the 219 counted in 2011 when the study began.

Surfers, swimmers and ocean bathers should not start humming the ominous two-note “Jaws” theme just yet. The chances of having a hostile encounter with a shark are still very low. More people in the United States have died from falling into sand holes, according to data collected by the University of Florida.

In fact, a stable white shark population off the coast is actually a good sign for the region. It indicates that there is a thriving marine ecosystem along the Coastside. An increase in sharks in recent years means ocean conditions are improving.

“Great white sharks are apex predators. In any system, it takes a strong foundation of the overall ecosystem to support an apex predator,” said Kanive. “A healthy population of white sharks means a healthy population of the seals and sea lions they eat, which means that the lower levels on the food chain, like fish, are healthy too.”

The researchers expect that the increase in white sharks can be attributed to the 1994 law prohibiting white shark fishing and the 1990 bans on the use of gill and trammel nets in California. More prey resulting from the Marine Mammal Protection Act in 1972 may have helped to bolster the population as well.

“The white shark has experienced over 25 years of protection,” said Kanive. “You can no longer target the white shark or possess any fins or jaws or teeth, both on a state and federal level.”

A parallel study indicated that juvenile great white shark populations in California have migrated northward as climate change warms ocean waters.

Despite the findings, the white shark remains classified as a vulnerable species by the International Union for Conservation of Nature — a fact that makes tracking the creatures all the more vital. However, funding for research is scarce. Kanive hopes to raise money to continue to monitor the white shark populations off of the California Coast.

Because the white shark has a life span of up to 70 years, collecting data over an extended period is important to accurately assess population dynamics.

“Our research is established. It's a long-term population study, which is fairly rare in this day and age, but it's something that can be done efficiently, effectively, and on a reasonable budget,” said Kanive.

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