Small bones, big impact on fish harvesting regulations

HOMER, Alaska (KTUU) — Summer is the season in which many Alaskans look to fill the freezer while scientists spend their days in the field collecting data from some of the daily catches.

An otolith bone under microscope shows the bands that form each winter, which researchers use to tell a fish's age. (KTUU)

"We went out for halibut and we came back with halibut," sport angler Fred Coffifield said. He, his wife and a few family members spent Thursday fishing out of Homer.

The Alaska town filled with natural beauty proudly promotes itself as the "halibut capital of the world." But it's not just anglers looking to win the derby or prepare their best Halibut Olympia who seek the denizens of the deep.

Kerri Foote is a fishery technician with the Department of Fish and Game. Her job is to collect halibut and rockfish carcasses. During her shift, she visits fillet tables on the Homer Spit, takes the donated fish and measures the length, records the sex, and removes the otolith -- a bone from the fish's ear.

"It allows us to ask the question of how many fish we can take from a fishery every given year," said Martin Schuster, a fisheries biologist with Fish and Game.

Otoliths show researchers the age of a fish through a series of dark bands formed during each winter. "That age data is really useful to predict how many fish are going to be available in the future," Schuster said.

Halibut otoliths are sent off to be part of the International Pacific Halibut Commission's database. Schuster said the organization has one of the oldest fishery data sets on record, with information dating back to the early 1900s.

Just off the Spit, rockfish otoliths are studied at the Fish and Game office in Homer. The bone is cut in half, baked and covered with mineral oil in the lab and studied under microscopes.

Once the bones have been processed and reviewed, the biologists send the information to managers with Fish and Game. "Without knowing what fish are doing out of the water, it's really difficult to assess what kind of regulation do you want to put on a fishery in the following years," Schuster said.

The fishery technicians are working to collect data for the research project in Homer, Seward, Kodiak, Valdez, Whittier, and Ninilchik.

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