Fred Bennett has been a fisherman for about 60 years and he just stared, perplexed, at a graph supposedly showing a halibut, tagged to track its progress, moving in the water column.

He shook his head in consternation and looked at fellow captain Mike Anderson who has spent more than 40 years on the water.

How is that possible? Bennett wondered.

Anderson was laughing.

It’s not, he said – unless the storied flat fish had been eaten by something, most likely a great white shark.

“The tag was hanging out near the bottom during the day and was near the surface of the water during the night time, plus the tag temperature shot up suddenly and stayed there – pretty clear indications that it was eaten by a shark,” agreed George Maynard, research coordinator at the Cape Cod Commercial Fishermen’s Alliance.

Stumping Bennett and Anderson would be tough. The two spent many years catching halibut, a great-tasting fish that is making fishermen money in Canada, and used to make fishermen money here. But stocks crashed, and for the last 18 years local fishermen have been allowed to land only one fish per trip, and that one has to measure at least 41 inches.

“We don’t have a halibut fishery,” said John Pappalardo, chief executive officer of the Fishermen’s Alliance, at a recent community gathering called “Meet the Fleet” in the Captain Harding House, the Fishermen’s Alliance home base.

The Fishermen’s Alliance is involved in an effort to bring the once lucrative fishery back. Fishermen believe there are a lot more halibut swimming off the Cape than have been counted, particularly since Canada has a robust halibut fishery worth millions of dollars annually, and fish don’t think too much of international boundaries like the Hague Line.

The Fishermen’s Alliance recently created a research staff position for studies like these, and hired Maynard. Working with regional partners including The Nature Conservancy and the School for Marine Science and Technology at UMass Dartmouth, the group is using a federal grant to better understand how many halibut are here and what they are doing. The hope is fishermen soon will be able to add halibut into their business plans.

“We need science to make good public policy,” said Pappalardo.

The study is two-pronged. Fishermen are providing up to 275 halibut samples to assess their age and sexual maturity, which will help scientists figure out when the long-lived fish spawn.

“Thanks to fishermen we have collected more fish in the last year and a half than the federal trawl survey did in the last 10 years,” said Maynard.

The second piece is tagging and releasing live fish. If they aren’t eaten, the satellite tags are designed to pop off in just under a year.

Anderson and Bennett have fond memories of going for the big fish, which is in the flounder family.

“There was a lot of halibut around, it was exciting,” said Anderson, who started fishing on Cape in 1967.

Halibut was fun to catch, he said, adding that they were fighters.

“Very aggressive fish,” said Anderson.

It was a winter fishery, Bennett explained. Come February, fishermen would leave anytime between 11 p.m. and 3 a.m. to get on the grounds. There were generally three people on a boat and the crew would bait on the way out. Some of the most talented could bait 250 hooks in 12 minutes.

“I could never do it,” said Bennett.

“That’s why you were the captain!” said Anderson.

The long lines – there were about 12 to18 feet between each hook – were then put into the water. Since halibut don’t like hard bottom, fishermen would look for “halibut moss” and use wax on the end of their sounding lead. If the wax was cut it meant there were mussels below and therefore no halibut.

This was before boats were packed with electronics. It was also before the Magnuson-Stevens Act, which kept the foreign fleet at least 200 miles offshore.

“When we left at night it looked like Times Square,” said Anderson, because there were so many well-lit big boats offshore.

Even back then, there weren’t a lot of halibut by historic standards; fishermen were catching them on cod trips. The catch had dropped from 5,000 metric tons in the early 1900s to basically nothing.

But their commercial value was sky high.

“If we had 2,000 pounds it would be worth more than all the other fish in the ocean,” Bennett said.

Anderson has some advice for future halibut fishermen. The consummate storyteller remembers leaning over the side of the boat trying to gaff a 300-pound halibut.

“Stupid,” he said, because grabbing a big fish like that would have the unintended consequence of tossing him into the drink. As it turned out, he missed. “It dawned on me, after, that it was probably the best thing that could have happened.”