A filmed underwater confrontation between an environmentalist who wants to shut down the aquarium-fish industry in Hawaii and a collector who gathers the fish and sells them for a living has put a spotlight on a long-running conflict over the business.

The video shot off the west coast of Hawaii Island shows a collector quickly swimming about 30 to 40 feet toward a diver who is filming them and ripping out her air-supply regulator. A snorkeler watching from above filmed the scene with another camera.

The state Department of Land and Natural Resources, which oversees state waters, said it is investigating "complaints by two parties involved in an incident" but declined to provide details.

Rene Umberger, whose regulator was ripped out of her mouth, said she followed her training and calmly retrieved the regulator, gave it a gentle first breath to test if it was functioning and resumed breathing.

"Doing something like that to someone — you potentially cause them to die," said Umberger, who leads a Maui-based group called For the Fishes. "I was shocked."

The act could have killed a less experienced diver, said Umberger, who said she has been a dive instructor for 30 years and has been on more than 10,000 dives.

Umberger said an enforcement officer from the Department of Land and Natural Resources told her the aquarium collector had filed a complaint against her for harassment. She hasn’t been served with the complaint, Umberger added.

The state hasn’t charged the aquarium fish collector with any violations. The activists, who released the video this week, identified him as Jay Lovell.

His telephone number isn’t listed, and he couldn’t be reached for comment. But his brother Jim Lovell, who also collects aquarium fish, said the activists were harassing divers and provoked an incident.

"From what I understand, Jay was getting scared of what going on," Jim Lovell said. His brother was trying to do his job, he said.

Makani Christensen, an Oahu scuba spear fisherman who said he spoke to the brothers, said activists are trying to disrupt the work of fishermen.

"The fish go away. You can’t work under the stress when you have eight different divers around you," Christensen said.

Hawaii’s aquarium fish collectors reported catching more than 550,000 specimens worth $1.1 million in 2009, according to a state report published in 2010. The value of the actual catch, however, may be two to five times that amount, the report said.

The two most commonly captured species are yellow tang, which, as its name indicates, is bright yellow, and goldring surgeonfish, which are blue, yellow and rusty red with white stripes.

Fishermen off the Kona coast, where the incident occurred, account for 75 percent of the aquarium fish caught in Hawaii. Aquarium fish collecting is legal off Kona, but fisherman must avoid certain places and collect only certain species. The incident occurred in Keawaiki Bay, where collecting is allowed.

Some environmentalists are passionate about stopping aquarium fishermen, saying the trade strips coral reefs of fish that eat algae and otherwise support a healthy marine ecosystem.

Robert Wintner, executive director of the Snorkel Bob Foundation, said his group set out to document what the fish collectors were doing on the dive.

Wintner spent five years lobbying Hawaii lawmakers for legislation to control or ban the aquarium trade, but none of the bills passed. The campaign is now shifting to documentation, he said.

Wintner has enlisted the help of the Sea Shepherd Conservation Society, which is best known for attacking Japanese whaling vessels off Antarctica, to help.

"Underwater is under the radar. Our entire objective is to bring a little sunshine on this, bring these facts to surface," he said.

Kona coast environmentalist Tina Owens, who has campaigned against overfishing for decades, said the incident is not typical of the area. Tensions between environmentalists and fishermen have eased significantly since fishing regulations were established under the West Hawaii Fishery Management Council, she said.

Sixteen or 17 years ago, "it used to be pretty wild" with collectors threatening tourists and fishermen threatening to "blow collectors out of the water," she said.

"Way back when, I was getting death threats and stuff like that — and now I have lunch with some of these guys," said Owens, who is executive director of the Lost Fish Coalition.