Gary Gilbert had no business catching a monster muskie that measured two inches longer than the state record.

He and his wife, Ann, wanted walleyes. Since Opening Day this year on Mille Lacs, they have caught and released more than 250 of them, including many over 20 inches.

But on June 17, the hot bite had to wait. They launched their boat about noon from the public access in Shaw-Bosh-Kung Bay, south of Garrison. Three miles east of the landing, still motoring to their fishing hole, they saw what looked like a giant walleye, belly up.

“I was feeling kind of bad about it,” Gary said. “I thought, ‘That’s probably the biggest walleye I’ve ever seen.’ ”

Instead, the Becker couple had stumbled upon a decaying 59½-inch muskie. Death blanched its coloring, but its body was fully intact.

“Look at the size of this thing,” Gary remembered saying as the lunker stretched out across the bow of his 18¾-foot-long Lund Pro Guide boat.

Gary and Ann took turns measuring it against Gary’s fishing pole, each pinching the tail the way they thought it should go. Then they snapped photos of the formerly elusive water wolf and returned it to Mille Lacs. At home, they were told by a friend that its length exceeded the state catch-and-release muskellunge record (56⅞ inches) set one year ago on Pelican Lake.

DNR fisheries biologist Steve Mero said Tuesday that the fish could be 18 or 25 years old. That’s because the dead muskie’s right pelvic fin appears clipped in the Gilberts’ photo, he said. According to DNR muskie stocking records, technicians clipped the right pelvic fin of fingerlings before they entered Mille Lacs in 1992 and 1999.

Mero said the fish likely had exceptional growth. It has the same color and build as the Leech Lake strain, he said. “Most muskies, regardless of lake or strain, will never attain these types of lengths,” Mero said.

Jim Wolters, the DNR’s fisheries supervisor in Fergus Falls, said a 55-inch muskie washed up on shore two years ago in Otter Tail County. His staff removed the cleithrum bone from under the gill plate and estimated the creature’s age between 17 and 19 years.

Hearing about the Gilberts’ find, Wolters said Tuesday that few muskies ever get that long.

“I must say that is one of the largest muskies I have heard of lately, dead or alive,” he said.