The fishermen believed that the humpback whale, already struggling to shake off a rope cinched to its massive body, would be even more bewildered by a boat ejecting humans into the water.

Nicholas Taron and Sam Synstelien needed a way to communicate a simple message to the whale: We want to free you.

The crew blasted the volume on the radio and transmitted loud messages into the waters off the central California coast as the whale swam in panicked circles, as if tethered to the seafloor.

“We were saying to the whale, ‘We’re your only hope. No one is coming here. You’re either going to let Sam jump on you — or you’re on your own,’ ” Taron told The Washington Post on Friday.

The whale’s life was potentially in danger. Netting and ropes can exhaust and drown giant sea mammals, experts have said, or cause wounds that attract sharks.

Humpback whales can grow as long as 60 feet and weigh up to 40 tons, according to National Geographic. Taron’s boat, by contrast, is 27 feet long.

This particular whale, though, seemed to understand the message it received as it drifted in the water, Taron said.

Some of the ropes caught on the end of the animal’s powerful, notched tail were tied to a buoy. The men cut the lines, and a few slipped free.

But someone still needed to release one last rope tightening on the whale’s back, the men decided.

They had stayed with the whale for more than two hours, Taron said, and radioed the Coast Guard and called the National Oceanic and Atmospheric Administration for help.

It may take awhile for a responding unit to arrive, Taron said a responding Coast Guard official told him over the radio, before asking for the two fishermen’s last coordinate and suggesting they could be “dismissed” from the area.

An unidentified bystander on the radio channel suggested they dive in, Taron said.

But the fishermen are not whale rescuers. They harvest monstrous-looking hagfish, also known as slime eels, for the clouds of ooze they emit.

“We’re totally not qualified for this,” Taron said, referring to rescuing whales that can grow longer than a school bus.

And yet.

Synstelien surveyed the water, the whale and the constricting blue rope. He hesitated for a moment.

“Get it, Sam. Jump on the whale right now and cut it!” Taron yelled, in video he took of the incident and posted Sept. 27.

Synstelien leaped, blade in hand, into the cold water off Morro Bay.

The whale’s blowhole erupted in a dry shriek as Synstelien made his way to its dorsal fin. He climbed aboard, holding the rope on its slick body like a bull rider.

“Get it, get it. Before she dives!” Taron called out.

Synstelien held his grip. The rope was tight and difficult to maneuver under, “like a piece of floss around your arm,” Taron explained.

Synstelien slid his hand in and sliced the rope away. At the same moment, the whale’s tail rose from the water and struck the side of the boat. Taron let out a groan. He had almost dropped his caseless cellphone into the water.

Taron panned to find his partner bobbing nearby. “Did you get it?” he asked.

Synstelien held the knife in his teeth and raised his arms in triumph. “Yeeeah!” Taron roared in the video.

“We were psyched,” Taron recalled. He does not know why a month-old video has only recently gained prominence, though he speculated it circulated on social media until news outlets began to notice.

Officials warned it was perhaps not the right way to deal with a trapped whale.

The incident could have gone a lot worse, said Coast Guard Petty Officer Mark Barney, a spokesman for regional operations.

The whale could have rolled on top of Synstelien, the rope could have tangled him too, or the whale could have crushed him against the boat, Barney said.

“All kinds of things could have gone wrong,” he said.

It has turned tragic for professionals in that actual line of work. Joe Howlett, a Canadian fisherman with 15 years experience freeing entangled whales off the Canadian coast, was killed during one such operation to free a right whale last year.

NOAA, which confirmed the whale was a humpback, appeared to refer to the death and others like it in a statement, saying people have been killed in similar incidents.

The agency said it is relieved there were no injuries, but it is worried the video could give civilians the same idea of undertaking a dangerous mission usually performed by trained responders using specialized equipment.

“Best practice for dealing with an entangled whale is to never get into the water with it, as these animals are very powerful and dangerous in close proximity,” NOAA Fisheries West Coast Region spokesman Jim Milbury said.

“In addition, every entangled whale is not necessarily in imminent danger, meaning that there is time to wait for the authorized responders and not requiring these types of emergency actions. And cutting just the visible lines may not totally free the animal, making it harder for responders to help,” he added.

That danger was not lost on the crew, Taron said. Both he and Synstelien attended years of schooling for a marine transportation license and regularly encounter sea life. The whale was massive, and they understood it could have killed them even while on the boat.

But Taron and Synstelien felt they had to do something. “We were trying to help out a friendly giant,” Taron said.

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