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Massive rockfish caught in Southeast Alaska much younger than thought

Ben Anderson
Rockfish, depicted here with bamboo grass in an 1840 illustration by Utagawa Hiroshige, can live more than 100 years. A big rockfish caught recently in Southeast Alaska was thought to approach 200 years old, but results have come back that peg the fish's age at only 64. Utagawa Hiroshige illustration

State scientists have determined that a hulking rockfish -- weighing nearly 40 pounds and measuring nearly 3-1/2 feet long -- caught by Seattle angler Henry Liebman in the waters off Sitka, is much younger than its size would seem to indicate. Initially, many were hopeful that the massive fish could set an age record at more than 200 years old. But using age-indicating ear bones in the fish called otoliths, the Alasak Fish and Game Mark, Age and Tag Laboratory in Juneau determined it to be only 64 years old.

Instead of predating the U.S. purchase of Alaska from Russia, the rockfish was barely old enough to have seen Alaska reach statehood.

According to Troy Tydingco, Sitka area manager with the state Department of Fish and Game, the rockfish, a specific species called a shortraker, fell well short of the overall rockfish age record of 205 years set by a rockfish of another species known as a rougheye. The oldest-known shortraker rockfish has come in at 175 years of age.

"This fish was so big, so there was a potential for it to also be an old fish," Tydingco said. "I think everybody was surprised it was so young."

The fish's age was measured using those otoliths, which grow with the fish and can indicate age much like the rings on a tree. Tydingco said that the otoliths can become a bit unreliable as a fish gets far advanced in age, though that would be less of a problem with a fish of only 64 years old, which he described to National Public Radio as pretty "run of the mill" in terms of rockfish age.

Despite the surprising news about the fish's age, there's no denying it was a heck of a catch. Tydingco said the shortraker catch was a record for a recreationally-caught member of the species, though commercial fishing operations might turn up larger ones from time to time. He said that the angler, as far as he knew, took the fish home to eat and left the carcass with the fishing charter operator. That's where Fish and Game retrieved the otolith bones from, and the University of Alaska may now be interested in obtaining the skeleton.

So how did the fish manage to grow so huge in just six decades? Well, that remains a bit of a mystery.

"I would guess that the genetics and a good environment had something to do with it," said Tydingco.

Many people, reading news articles that the fish might be up to two centuries old, were a bit outraged that Liebman wouldn't have returned the big rockfish to the sea. But rockfish, which spend much of their lives at depths that can exceed 1,000 feet, have an organ known as a swim bladder that expands as the fish moves toward the surface. If it comes up quickly, as with a fishing line, the bladder can rupture and the fish could die. Liebman, fishing at that depth, likely had no idea what kind of monster he had at the end of his line.

Contact Ben Anderson at ben(at)alaskadispatch.com