Cool temperatures delayed the annual channel catfish egg harvest at Kansas Department of Wildlife, Parks and Tourism but the catch was still pretty good.
Several million eggs were gathered about two weeks later than normal because the temperature didn't get to the desired 74 degrees for egg laying until the start of the second week in June, said Brett Houdyshell, KDWPT hatchery biologist.
Water temperature plays a critical part of the egg laying process for channel catfish and other species as well.
Six ponds of the 87 ponds at KDWPT are dedicated to the spawning process with another eight dedicated to catfish holding ponds. In the spring when the temperature gets to 74 degrees, hatchery biologists will place from 25 to 30 15-gallon steel cream cans in the ponds in the warmest layer of the water.
The cream cans are very old and have a variety of business names on them but they are the favored method of providing a nesting area for the breeding catfish.
Catfish go though their breeding cycle one time a year so it is important for the biologists to be ready to go when the time is right.
The cans are anchored to the bottom of the pond and they are checked a week after they are set into position. Catfish seek a dark area they can defend to lay eggs and the cream cans fill the requirement.
Catfish that are five and six years old are used for breeding. When they get too big for the cream cans they are transferred to the Kids fishing pond at KDWPT headquarters.
Once the female has laid the eggs the male will move in the can to keep predators, like crawfish, away from the eggs. He also chases the female out because she would eat the eggs if she stayed, Houdyshell said.
The eggs are called spawn and are clumped together in a mass on the lip of the can. They are a bright yellow when first laid but change color to a dark red as they develop. Each female produces from 18,000 to 24,000 in one spawn. It takes about 12,000 eggs to make a pound.
When the eggs are ready for harvest, the biologist will harvest the eggs in five gallon buckets and transfer them to the hatchery.
The eggs are then weighed and placed in one-eighth inch hail mesh baskets in special long tanks filled with water. Above each basket is a metal paddle the moves back and forth continuously to provide oxygen to the spawn. Without this movement, the eggs would die, Houdyshell said.
The water temperature is raised from 74 degrees to 78 degrees so the eggs will hatch two days earlier. Earlier hatching means fewer problems with fungus and bacteria.
When the eggs hatch, the baby fish, called fry, simply fall through the bottom of the basket to the bottom of the trough.
The fry are collected and moved to 37 gallon rearing tanks that are 10 feet long and one foot wide. Each rearing tank holds from 180,000 to 190,000 fry.
They are fed a ground up fish product that is 52 percent protein.
Fry are left in the rearing tank for eight days then returned to the ponds where they will stay for two years until they reach half a pound. They will then be transferred to the various lakes around the state as needed.
The total hatching process takes 22 days.
Each year KDWPT biologists evaluate the fish populations at state lakes and if a population falls below a certain level they will request replacement fish from the hatchery. This year the hatchery received requests for a total of 2.25 million fry.
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