GARRISON, N.D. — From the incubator jars inside to large holding ponds outside, from tiny walleyes emerging from their eggs to giant pallid sturgeon circling massive holding tanks, the Garrison Dam National Fish Hatchery has been experiencing one of its busiest spring seasons on record.
Millions of walleyes, northern pike and perch are being raised under the watchful eye of fisheries biologists. The high volume of young fish is needed to stock a high number of North Dakota lakes that suffered winterkill.
Northerns boom
“This is the most northerns we’ve ever produced in the 17 years that I’ve been here,” said Jerry Tishmack, a fisheries biologist. “The quality has been great. We’ve had up to 86 percent hatching success on pike. That’s double what we normally get. We can’t say for sure on the walleyes yet, but they do look above average.”
Tishmack believes cool weather throughout the northern pike and walleye egg-taking season caused less stress on spawning fish, meaning better eggs were brought to the hatchery. Adult perch were netted and then released into specially equipped outdoor holding ponds at the hatchery, where it is expected they will spawn naturally.
“We put 75 pairs of perch in each of eight ponds that contain netting material,” Tishmack said. “We did an experiment a couple of years ago, and the perch liked spawning on the netting. It worked out real well. They do their thing outside instead of inside the hatchery, where we have to control fungus and other things.
“I’m hoping for 175,000 perch per pond, if the birds don’t eat them all,” he said.
Cormorant threat
Tishmack was referring to fish-eating cormorants that know the address of the hatchery and can be seen sitting near outdoor ponds where young fish are being raised. They are excellent fishermen and can take a toll on fish production. Keeping them away from the ponds can be a full-time job.
Inside the hatchery this past week, millions of newly hatched northern pike were showing signs of seeking food. That meant they were nearly ready to be moved to outdoor ponds to continue their growth.
“It takes about 20 days for the pike to reach 1ΒΌ inches in length,” Tishmack said. “For walleyes to do that, it takes about 30 days. Then they’ll be ready to leave the hatchery and be stocked out.”
Ground alfalfa
The hatchery uses ground alfalfa — 200 pounds every third day — in each of the outdoors ponds to stimulate plankton growth. The alfalfa also serves another purpose.
“It puts a nice, dark color on the ponds, which causes the water to heat up a little bit quicker,” Tishmack said. “Most of your plankton and micro-plankton and macro-plankton eat vegetative matter. So actually, you are coloring your water and feeding your zoo-plankton. It increases the fertility of the ponds.”
The plankton, from microscopic copopods to bloodworms and countless other invertebrates, provides a ready-to-eat food source for newly hatched fish.
Pallid sturgeon
Inside one of the hatchery buildings, five pallid sturgeon could be seen moving slowly through cold water in a large holding tank. The pallids — four males and one female — were the first to have been netted from the lower reaches of the Yellowstone River this spring. Fisheries crews will continue that effort in hopes of bringing more adult pallids to the hatchery, where they will be artificially spawned. The Garrison Hatchery has been a leader in the Pallid Sturgeon Recovery Program aimed at saving pallids in the Missouri and Yellowstone River systems from extinction.
Kim Fundingsland , Grand Forks Herald
Published: 05/18/2009
Subject: Garrison Dam fish hatchery has busy spring. 
Thu May 21, 2009 8:22 am
