The spawning season
November 7, 2005
Ostensibly, it’s all about trout at the Crystal River Hatchery. But it’s really about the birds and the bees.
From September to February each year, a small crew gives Mother Nature a hand in the production of rainbow trout and cutthroats in numbers that would make any angler giddy.
The hatchery, south of Carbondale, is one of 19 in the state operated by the Division of Wildlife. It produces 11 million trout eggs annually that are reared elsewhere. In other words, some 11 million fish that wind up in waters in Colorado and around the West begin their life at the local hatchery, where men in waders take the guesswork out of what happens naturally between an egg-laden female and an accommodating male.
The hatchery, a popular spot year-round for visitors who wander up and down the outdoor raceways to watch the schooling trout cruise back and forth, is especially popular these days. Groups of schoolchildren and others come to watch the action during spawning season.
The hatchery crew wades into the spillways five days a week to harvest eggs from “ripe” females, or those swollen with eggs.
In the wild, the rainbow and cutthroat strains would spawn in the springtime. In the controlled environment of the hatchery, water temperature and light are manipulated to extend the spawning period and increase the facility’s egg-production capacity. Still, there is no time to waste when the time comes.
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“They [females] ovulate once a year ” you have to be ready when they’re ready,” explained John Riger, wildlife technician and hatchery superintendent at the Crystal River facility. “The males are always ready,” he added with a grin.
The fish are briefly anesthetized in a tub of water to ease in their handling. Gently pressing the underside of a female will force a string of eggs into a bucket. Then, the trout are tossed back into the raceway, where they regain consciousness and resume swimming almost immediately.
Several males are also selected; their milky milt is added to the bucket of eggs in much the same manner.
The hit-or-miss nature of natural reproduction ” in which eggs can be devoured by predators, washed from a river bottom by spring runoff or lost to a host of other circumstances ” is virtually eliminated in the controlled environment of the hatchery.
“They have a reproductive system that’s hugely productive, but inefficient,” Riger said.
In the wild, one-third of 1 percent of the eggs that are laid will become trout that survive to reproduce, according to Riger. At the hatchery, the success rate is 94 percent.
Inside the hatchery, the newly fertilized eggs are delicately incubated in flowing water piped from nearby springs. In just three weeks, the eggs are “eyed” and ready to ship ” a dark spot in the translucent, salmon-colored orbs is the eyes of a trout within. In four weeks, they will hatch.
Most of the eggs are sent elsewhere to be reared. The fry that are kept at the Crystal River Hatchery move to one of its 900-foot raceways when they’re about 2 inches long. There, they grow into brood fish ” ages 2 to 4 for females and age 2 or 3 for males. More females than males are kept on hand. On a day in September, the hatchery had 41,527 fish of various ages in its care, according to Riger’s tally.
So many trout in a concentrated area proves more than tempting for some clandestine hatchery visitors.
Hanging on a bulletin board inside the hatchery offices is a collection of lures and flies pulled from trout after botched attempts to catch and land them. Some of the hatchery crew lives on-site, helping thwart fishing expeditions, but clearly some anglers make the attempt.
“We don’t dare leave a dip net lying around, I tell you,” Riger said.
At the hatchery, with an average water temperature of 50 degrees, a trout will reach 10 inches within a year ” the size of what the DOW considers a “catchable” trout for stocking purposes.
No trout from Crystal River are currently used to stock waters that produce natural trout populations, however. In the spring of 2004, two fish collected in a routine sample at the hatchery tested positive for whirling disease, which decimated the DOW’s trout production in the late 1990s and required an $11 million effort to clean up many of its hatcheries.
The division’s trout production plummeted to about 300,000 catchable fish in 1998. This year, the DOW will plant a projected 2.5 million fish from division hatcheries and private sources.
Whirling disease is a parasitic infection of trout and salmon. Heavily infested fish can become deformed or swim in circles ” hence the disease’s name. Eventually, highly infected young fish may die. The disease has wiped out natural populations of trout in some waters, but it does not affect humans.
The Crystal River Hatchery hasn’t seen another incidence of whirling disease, but has not yet been cleared to produce trout for stocking in wild trout habitat ” the nearby gold-medal Roaring Fork River and the Fryingpan, for example. Trout from the hatchery ” including some sizable fish ” are stocked in habitats where they will only survive for a short period. That typically means urban lakes and reservoirs on the Front Range and far Western Slope, where they are placed specifically so people can catch them.
Eggs cannot carry whirling disease, nor is it transmitted from trout to egg. So, the hatchery continues to raise brood fish specifically for the production of eggs. That will always be the hatchery’s primary role, according to Rich Kolecki, DOW chief of hatcheries, based in Denver.
“We have five brood stations in Colorado, Crystal River being the major one.” he said.
Still, the discovery of whirling disease in the hatchery was both a surprise and a disappointment, Kolecki conceded. Aquatic managers suspect infected irrigation water from the nearby Crystal River somehow infiltrated the hatchery’s clean, spring-fed system.
The DOW is currently beginning what will be at least a 14-month effort to declare the facility whirling disease-free. Specially designated and tagged “sentinel fish,” placed throughout the hatchery, will be tested for the disease.
It could take two-plus years, however, before the hatchery is cleared, according to Kolecki.
In the meantime, Riger said he has overseen the production of roughly 380 million eggs and counting.
When children visit the hatchery, he asks: “How may of you like to fish?” Little hands shoot skyward.
“That’s why it’s important ” what we do,” he said. “Trout can’t reproduce as fast as the millions of us who want to fish and catch them.”