Margaret Shaughnessy stood rib-deep in Mexico's Sea of Cortez rocking an enormous roosterfish in the water, hoping it would swim away and take her fly-fishing infamy with it.

Margaret Shaughnessy stood rib-deep in Mexico's Sea of Cortez rocking an enormous roosterfish in the water, hoping it would swim away and take her fly-fishing infamy with it.

The co-owner of a Medford fly-rod company spent nearly four hours fighting this fish on a prototype 10-weight rod, both to exhaustion.

The only certified scale they had handy topped out at 60 pounds, and her catch maxed it out, which more than doubled the women's world record for a roosterfish taken on a 20-pound tippet.

Based on its length and girth, its real weight could have eclipsed 100 pounds, but it would have had to die to confirm that truth. And Shaughnessy wasn't going to let that happen.

She pressed the fish forward in the water, pushing oxygenated seawater through its gills as her right hand sensed the strength returning to its powerful tail.

"There was just no way we were going to kill that fish," says Shaughnessy, 48, of Medford. "We didn't even discuss it for a second. It was never an option."

With a little more help, the roosterfish swam back to the depths of the sea on June 2, 2013, a triumphant ending to a day that shows that sometimes nothing needs to die to make for a record fish story.

Officially, the fish has been recorded as a 60-pounder in the International Game Fish Association's world-record rolls for women fly-fishers, because the IGFA won't and never will certify records based on estimates.

Shaughnessy will take the 60 pounds and a live roosterfish over a 100-pound carcass 100 times out of 100.

"That record would probably stand for a really long time, if not forever," Shaughnessy says. "I've had people literally mad at me that I didn't kill that fish. I've never killed a game fish. Never will."

The roosterfish and Shaughnessy's epic battle with it made IGFA's 10 "Best Catches" of 2013. That makes her a candidate for its inaugural Anglers' Choice Award in online voting that runs through March.

The fact that it more than doubled the previous record of 29 pounds set in 2012 in Baja, Mexico, is a rarity in itself, says Jack Vitek, the world records coordinator for the Florida-based IGFA.

"All those things, plus the fantastic pictures, make it really impressive," Vitek says. "It's a great record and a pretty cool story."

Shaughnessy says she's just a bystander in this best-catch crowd.

"It's definitely about the fish," she says.

It's always been about the fish in the Shaughnessy household, where Margaret and her husband, James, own and run Beulah Fly Rods while raising two kids and scratching the big-fish itch whenever possible.

In Mexico, it's roosterfish, a popular saltwater target known for their impressive power as well as the "rooster comb" of seven long spines on the dorsal fin, like that on a redleg's head.

The couple have spent a month camping and fishing out of LaPaz yearly since 1985, and she has recently set a handful of women's world fly-fishing records while fishing out of a panga guided by long-time friend Marco Antonio Green Lucero.

Their method of choice is to toss small herring into the ocean to get roosters to respond, then cast streamers into the feeding frenzy in hopes that fast, long strips will entice a big rooster to grab the fly, turn and run.

Shaughnessy used that method to set a women's record with a 21-pounder on 20-pound tippet in 2011, only to see it broken by a 29-pounder a year later. So she set out to get one of at least 30 pounds to reclaim her world record.

Over several days of fishing, she caught roosters of 26 pounds and 28 pounds, but no new record heading into her last day of fishing before returning to Medford.

That afternoon, the trio waited for the regular fleet of roosterfishers to head to port before they motored to their favorite spot and tossed out their live chum. Roosterfish boiled everywhere, but Shaughnessy couldn't get one to bite.

They ran out of herring and went back for another batch, but Shaughnessy was simply feeding roosters and not hooking them.

Down to just a few more herring in the boat's live well, as Shaughnessy stripped her streamer madly through yet another group of uninterested roosterfish, a large shadow ascended from beneath the boat. It grabbed the fly and careened away, instantly chewing into her backing.

"It was a tenacious fish," she says.

The rooster made great runs and they followed, rarely getting close. An hour and then another passed without Shaughnessy gaining ground on her fish.

Fly-fishers never feel like they have the upper hand when they are down to their backing — the braided running line tied to the plastic fly line to give the reel more line capacity.

"It was crazy," she says. "I'd see that knot and I'd think, 'OK, it's almost over.' Then the fish would scream away and you could smell the reel burning."

That knot returned just inside her rod guides, but the fish would not budge for 20 minutes. Finally, it swam in tight circles until it was at the boat with Marco's hand firmly around its tail.

"We were all stunned," Shaughnessy says. "I really couldn't stop screaming. It was such a mix of feelings. Giddiness and exhaustion."

Knowing the fish was a record, they put its enormous head in the live well and motored for shore because the IGFA requires certified weights be taken on land.

Once there, they lifted it with Shaughnessy's IGFA-certified Boga-Grip, which hit the 60-pound limit and stopped.

At 63 inches long and with a 36-inch girth, formulas used for estimating caught-and-released fish put it at 102 pounds, minimum.

"Anyone who knows fishing knows that thing isn't just 60 pounds," Vitek says.

With no better scale at hand, they rushed the fish back to the water for its successful revival.

"It was one of those once-in-a-lifetime things," she says.

So the roosterfish officially stands at 60 pounds. Those who simply scan the IGFA records will never know the long, exhausting way the record came to Shaughnessy and how she let fly-fishing infamy fin away.

"I had my ass kicked by that fish, but in a fun and good way," she says.

Reach reporter Mark Freeman at 541-776-4470 or