Water is piped down the center of these jars then flows up from the bottom. This action, combined with a clay treatment applied in the field, keeps the eggs in suspension and prevents clumping. Hatchery biologists monitor the eggs closely as incubation advances. Water flows are checked to ensure constant but controlled movement. Water temperatures and oxygen content are also routinely checked.
Dead eggs rise to the top of the jars and are siphoned off each day.
At 60 degrees, hatching generally occurs on the eighth or ninth day of incubation. As the fry break out of their egg cases, they swim and are carried upward by the water into large circular holding tanks where they are held for two to four days. Then, they are ready for stocking. Some fry are stocked in hatchery ponds to be raised to fingerling size and stocked later in the summer. Specially designed hatching jars are used to regulate hatching procedures and increase survival rates.