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By BILLY SINGLETON
Daily News Staff Writer
Thursday marked a key step in the life cycle of summer coho salmon produced at the Southern Southeast Regional Aquaculture Association’s Whitman Lake Hatchery: spawning.
Hatchery workers killed and spawned about 300 female cohos over the course of the day, producing roughly 630,000 eggs. Those eggs will be grown at the Whitman Lake Hatchery, released as smolt from Whitman Lake and elsewhere, and go on to support Southeast Alaska’s sport and commercial coho fisheries.
The fish that SSRAA spawned on Thursday had been produced at Whitman Lake and were released into the ocean in May 2017. Between 2,000 and 2,500 of those fish survived and successfully returned to one of the hatchery’s raceways this summer.
“They come right up the ladder and swim into the pond,” Whitman Lake Hatchery Manager Jay Creasy explained. “... Their nose basically tells them where to go.”
The returning fish were the first group of summer cohos released by the hatchery. Creasy said that the return was somewhat lower than he had hoped.
The summer coho resided in the hatchery’s raceways for a couple of months as they prepared to spawn. SSRAA began spawning those fish the week before last.
On Thursday, eight SSRAA employees fired up their spawning station at Whitman once more to spawn an additional 300 female salmon.
The spawning station is an outdoor, assembly line style setup beside the hatchery’s raceways and fish ponds.
The cohos were lifted out of their raceway by a device called an Archimedes’ screw — a large rotating screw used for lifting water and, in this case, fish.
The fish flopped down a chute into a tub of anesthetizing solution. When they were sufficiently knocked out, Creasy checked the bellies of each female to determine whether it was ready to spawn. Those that are ready were killed and passed along to the next station.
The salmon that were “green,” or not yet ready, were thrown back in the raceway to spawn another day. All males are typically ready by this stage — some are used and some thrown back in order to maintain equal numbers of males and females.
Hatchery workers in gloves and full rain gear then cut open the female salmon and deposited their eggs into a plastic bin. The eggs of one female were mixed with milt from two males. Each female produces 2,100 eggs on average.
Throughout the process, workers continually rinsed their clothes, gloves, knives and fish with a disinfectant iodine solution in order to prevent the spread of any bacteria or diseases to the eggs.
The bin containing the fertilized eggs then went to one of the hatchery’s incubation rooms, where another worker rinsed them to remove any potential contaminants and placed them in trays for incubation.
When the remaining eggs are deposited, Whitman Lake’s supply of summer coho eggs in incubation will total about 1.4 or 1.5 million, though Creasy noted on Thursday that these numbers are hard to predict as the average number of eggs per salmon tends to vary.
SSRAA plans to grow the resulting fish at the Whitman Lake and Burnett Inlet hatcheries. Creasy estimated that around 90 percent of the eggs will survive until they become coho smolts and are ready for release.
The smolts will be released in spring 2020. More than a million of the coho smolts are planned to be released at Neck Lake on Prince of Wales Island. Around 200,000 will be released from Whitman. Those released at Whitman in 2020 will return again for use as broodstock, and the cycle will begin again.
Also on Thursday, employees of SSRAA’s Research & Evaluation Department tested the female cohos for bacterial kidney disease, or “BKD.”
Whitney Crittenden, a lab employee, explained that the disease is naturally occurring but can spread rapidly when fish are concentrated in hatchery raceways. For that reason, the Alaska Department of Fish and Game requires testing.
The workers removed small samples of each female fish’s kidney and marked their containers. The samples will be frozen and shipped to a Fish and Game lab in Juneau for testing. The eggs belonging to any fish with high levels of the disease will be dumped out to limit the spread of the disease.
“And BKD — this isn’t something that people need to worry about,” Crittenden added. “It doesn’t affect humans at all. It’s just something that fish get. They have their bugs just like we do.”
Asked if there is a sense of accomplishment in seeing the fish he took as eggs several years ago complete a life cycle and return as fully grown fish, Creasy said on Friday that he doesn’t feel too sentimental about the individual fish. Rather, his focus is on doing the best job he can.
“As far as naming all the fish or rejoicing upon their return, I don’t see that happening so much,” Creasy said. “… It’s more of a feeling of accomplishment that you did a good job with these fish. When you feel like you did the best job you could, that’s rewarding.”