Shark populations are slowly increasing in Long Island Sound, but the species showing up in greater numbers pose little known risk to swimmers, according to state and marine science experts. That's a relevant point as Greenwich's Long Island Sound beaches head into the final weeks of summer.

Connecticut Department of Energy and Environmental Protection marine fisheries biologist David Molnar said Friday, Aug. 21, that populations of brown sharks (also known as sandbar sharks), dusky sharks and sand tiger sharks are rising in the Sound, based on data collected through DEEP's new coastal shark reporting app. The app allows anglers, boaters and charter captains to log sightings.

"These shark species do not feed on humans, attack humans," Molnar told CT Public. "They're primarily fish eaters."

Molnar pointed to two drivers behind the increase: fisheries management rules that protect sharks, and warming water temperatures in the Sound. More than 700 brown sharks were reported in Connecticut waters in the year leading up to August 2026, according to DEEP data. Sandbar sharks are a protected species in the state, and anglers who accidentally hook one must release it.

The species had nearly vanished from these waters decades ago. DEEP officials say the sandbar shark has made a significant recovery after years of very low abundance in the 1970s, 1980s and 1990s.

In an Aug. 4 WTNH report on growing brown shark numbers near the Connecticut River, Molnar said the animals "are expanding their range" due to warmer waters. "They are cold-blooded animals; they like the warmer water," he said at the time.

David Cochran, senior director of fish and invertebrates at Mystic Aquarium, echoed the reassurance. He said the risk of a harmful encounter is very low and advised beachgoers to simply give any shark they see space.

"They're not out there marauding and looking for anglers or swimmers or anything like that," Cochran said. "They're just out there living their lives."

Cochran added that more sharks actually signal a healthier Sound ecosystem, because top predators indicate a strong prey population supporting the broader food web. As for great whites, he said they can enter Long Island Sound but rarely linger because there isn't enough prey to sustain them.

Residents who spot a shark while boating or fishing can report it through DEEP's coastal shark reporting app, available online through ArcGIS Survey123.