Hatchery salmon make ultimate sacrifice for species’ survival
October 1, 2011
By Tom Corrigan
NEW — 6 a.m. Oct. 1, 2011
There are steps in the process that may not be pretty, but it’s all aimed at aiding in the survival of Pacific salmon.
In hopes of eventually releasing millions of young salmon back into local waters, workers and volunteers at the Issaquah Salmon Hatchery harvest nearly 2,000 mature chinook and coho salmon annually. They also take in kokanee from Lake Sammamish.
The chinook and coho check into the hatchery via Issaquah Creek. This year, the first fish arrived Aug. 23. Those tabbed to help with ushering in a new generation don’t check out.
Some people are surprised to learn mature salmon are killed for artificial breeding purposes, admitted Darin Combs, hatchery manager. Visitors can watch the fish being collected and processed. Combs said somewhat surprisingly to him, adults have the strongest negative reactions. Children aren’t as offended, sometimes asking to see the fish remains. The important thing to remember, Combs said, is that all salmon — males and females — die after spawning.
The first salmon to reach the hatchery are chinooks. Biologically driven to go upstream to spawn, the fish only have one way to go once they reach the facility, Combs said, and that is up the hatchery fish ladder and into holding ponds. The first harvest of male and female chinooks is completed in late September.
“You have to get your hands on the fish,” Combs said. “So you get in the water in your waders and you grab the fish by the tail one at a time.”
“Ripe” females are detected by the feel of their bellies. If the fish is ready for harvesting, the female’s eggs will be loose and the fish may even release a few of those eggs during handling. The test for males is much the same. Combs said the key again is to squeeze their bellies. If a fish releases the milky substance known as milt, it is ready for harvesting. Overall color and condition of fish can also be a signal, though Combs said it’s not the most reliable. Although it sounds somewhat odd, generally, a healthy looking, silver-colored fish is not going to be ready.
Fish deemed ripe for spawning are processed in one of two ways. The first is to strike the fish by hand using a bit of equipment that strongly resembles an old-fashioned police billy club, said hatchery foreman John Kugen.
The other method involves pneumatic machinery into which the fish are fed and dealt a blow to the head. The remains are then moved to what’s called the spawning table that sits next to the holding ponds. Pressure is applied by hand to each individual salmons’ abdomen. Eggs and milt are collected and, for now, preserved separately. The breeding materials are later mixed together, with the resulting fry kept in long troughs or in more modern vertical stacks. Early on in their lives, Combs said the young fry are kept out of the public eye as they simply are too fragile.
The breeding troughs are pretty much what they sound like: elongated cement pools in which young fish are kept. Both Kugen and Combs said the stack equipment is far more efficient. The youngsters are placed in what look like plastic drawers stacked one on top of the other in metal frames. Kugen said the stacks hold more fish and use less water than the traditional troughs.
In the case of the coho, after collecting 1.1 million eggs, Kugen said the Issaquah Hatchery aims for 450,000 “planting smolts” — fish that will be released in to the wild. Other cohos are given to various co-ops such as sports groups or used for the hatchery’s famous Salmon in the Classroom program.
The planting goal regarding chinook is about 2 million smolts from 2.3 million eggs. Young coho are guests of the hatchery for about 21 months from the time they are taken as eggs to the time they are released as smolts. Chinook are let loose much sooner; they are gathered in late September to early October and released the following spring.
Besides the smolts, the hatchery lets loose from the holding ponds about 1,000 chinook and the same number of coho to travel further up the creek, hopefully to spawn and die naturally.
What happens to the remains of the fish that gave their all for the survival of their species? Most know the basics of salmon reproduction, how the fish will return from the salt water of the ocean to the fresh water river or creek where they were born. What might not be as well known is that the trip is a fatal one for the fish even if they don’t spawn.
“Once they enter the fresh water, they start to die,” Combs said. “They don’t look very good after a while.”
By the time they are ready to be harvested for reproduction, they are often pale and thin, literally falling apart. The hatchery donates a certain amount of harvested salmon that remains edible to local food banks. The rest goes to a private seafood handler, which pays a fee for the fish. Not suitable for human consumption, those fish are turned into fertilizer or pet food.
Kugen added that before the remains go anywhere, they are run through a metal detector in order to search for any fish tags that might be present. The tags are a way of tracking fish born in other hatcheries. Usually, the Issaquah Hatchery doesn’t end up with too many fish born elsewhere, Kugen said, but they still need to keep track of the so-called strays. As are all hatchery fish, the removal of an adipose fin, a very small fin on the back of the fish, marks Issaquah fry.
As for the kokanee, Combs said the hatchery’s efforts are part of a plan to hopefully restore the fish to Lake Sammamish.
“The population there really is in trouble,” Combs said.
Adult salmon are caught in the lake using nets, Kugen said. They are brought back to the hatchery, where eggs and milt are harvested. Raising fry in the hatchery results in a much higher survival rate than if the fry were returned immediately to Lake Sammamish. Still, raising lake kokanee in the hatchery presents one major problem.
Salmon imprint into their memory banks whatever waterway they are born in; that is the water they will try and get back to as adults when they are ready to spawn. Issaquah Creek is the main water source for the Issaquah hatchery. If eggs from Lake Sammamish were hatched in water from the creek, the resulting fry would later try to reach Issaquah Creek instead of some of the other waterways that feed into the lake.
To solve the problem, the hatchery uses equipment known as remote sight incubators. The eggs and milt are introduced into special buckets that contain water from whatever creek conservation officials want the fry to return to as adults. Kugen said the program has worked extremely well, with a fry survival rate of 97 percent. Last year, from some 16,000 eggs, the Issaquah hatchery was able to release between 14,000 and 15,000 fish into Lake Sammamish.
Finally, the hatchery also works to raise rainbow trout, releasing about 30,000 a year into Pine and Beaver lakes. Kugen said the hatchery holds onto a few thousand every year until the fish get, as he put it, “nice and fat.” Local fishermen have been known to follow the trucks from the hatchery to one of the two lakes in order to try their hand at catching the prize-sized trout.
“That’s a very popular program,” Kugen said of the trout farming.