Most folks run from sharks. Sean Van Sommeran runs to them.

Since 1990, Van Sommeran has headed the Santa Cruz-based Pelagic Shark Research Foundation, a small but zealous band of dedicated shark lovers who strive to ensure that the ocean’s top predators thrive. The work has landed him a role in many of Northern California’s biggest marine stories, but he won’t be there for the latest one.

Recently, the Pelagic Shark Research Foundation started looking into a broad shark die-off near an upscale bayside development in Redwood City. In less than two weeks, Van Sommeran estimates as many as 50 – perhaps more – leopard sharks washed up dead, an aquatic mystery that he worries won’t be thoroughly investigated.

“The body count’s gone from several to a dozen to dozens to an unknown number,” said Van Sommeran, adding that it’s likely hundreds have been killed but haven’t washed ashore. “In this case, clearly, something has gone wrong.”

But on Wednesday, Van Sommeran was excused from the investigation. Despite being alerted to the situation by the U.S. Coast Guard, Redwood City officials told him they would work exclusively with the Department of Fish and Game in figuring out why dead leopard sharks, which can grow more than five feet, continue to dot the shoreline.

Van Sommeran fumes, saying he won’t stop looking into the situation. He theorizes that a system of lagoons and canals controlled by tidal gates led to stagnated water and depleted oxygen levels, suffocating the sharks. He wants to test both the sharks and water where they’re being found.

“What it amounts to is a huge outdoor aquarium, like Sea World but with less maintenance,” Van Sommeran said.

The situation, he said, is unparalleled, with possible implications for how local officials manage the system of lagoons.

“My concern is that this may have been going on longer and that they’re more concerned with damage control,” said Van Sommeran.

Van Sommeran’s work protecting sharks sometimes causes friction with the pedigreed authorities frequently put in charge of shark inquiries. He says he gets along with field researchers, but often runs onto resistance from top regulators and officials.

“When you go off into the upper management, they don’t like us. We’re unpredictable, and if I see something, I tell you what I see. I guess that’s regarded as a loose cannon,” he said.

Redwood City officials returned calls seeking comment. An email from a Redwood City official to Van Sommeran said the city would rely on the state’s conclusions on why sharks are dying, could not pay for any of the foundation’s work and declined to provide contacts for the city’s water quality testing contractors.

Leopard shark die-offs are not unheard of, and a Department of Fish and Game spokesman said the agency is investigating the matter. A Southern California-based state biologist, Mark Okihiro, is scheduled to arrive on the scene Monday.

The Pelagic Shark Research Foundation has always been a bit off the grid. Van Sommeran speaks with the vocabulary of a scientist but the drawl of a beach regular. His expertise comes from experience rather than formal education, often appearing on the scene through referrals from other groups.

“It’s like volunteer firemen. We just gas up our cars and go,” Van Sommeran said.

For research, he relies on contacts in the marine sciences field, and over the years has supported himself and his research by working as a security guard and other odd jobs. His main employment now is as a caregiver for his ailing mother.

“I was born and raised in Santa Cruz, raised in kind of a mariner background. I was fortunate enough to be on a boat from an early age, and like most kids had a fascination with sharks,” Van Sommeran said.

But founding a group to study sharks had its challenges. Saving seals? Sure. Whales? No problem. Yet getting people to back research into predators (and occasional killers) was another matter.

“They were like, ‘What are you, lame? That’s like protecting syphilis,'” Van Sommeran said.

But with the years came several landmarks, such as helping to get the fishing of basking sharks banned in Monterey Bay. In 2006, he pulled off a rescue of a live whale wrapped in fishing nets near Carmel Point. And in 2008, he found a B-movie monster – the remains of a 31-foot giant squid floating in Monterey Bay, a discovery that brought worldwide attention.

“He’s shark research for the common man,” said UCSC veterinarian Dave Casper, who priased Van Sommeran’s knowledge of sharks. “I don’t think he gets enough respect. I think his personality kind of rubs people the wrong way.”

Casper recalled a story from several years agao, when a fisherman put a rare great white shark that had been entangled in his equipment up for sale on eBay. An scientific outcry ensued, but Van Sommeran talked the fisherman into selling him the shark, which Van Sommeran then turned over to researchers.

“That wouldn’t have happened had it not been for Sean,” Casper said.

Before he was excused from the Redwood City investigation, Van Sommeran was given two specimens by Redwood City to study. A third is stashed in the freezer of a Redwood Shores resident, who did so on Van Sommeran’s request. By Thursday, he’d secured another. He is trying to find someone to test them, along with water quality samples from the lagoons.

Residents’ concerns over the sharks seems to match Van Sommeran’s, and they continues to update him regularly. And the problem seems to be growing rather than going away, with more sharks recently found outside the Redwood Shores development.

On Wednesday, Chris Tarkowski, who regularly walks the shoreline, located Van Sommeran through Google and reported four dead sharks, all found in Foster City northwest of where other sharks have washed up.

“We walk around here all the time and we’ve never seen anything like this,” Tarkowski said.