SALEM, Ore — An innovative system that replenishes oxygen delivered to rearing ponds is a pioneering effort in fish production at Gnat Creek Hatchery. The new system will help increase yearly production of spring chinook from 850,000 to 1.1 million.
The oxygen supplementation system will also boost the percentage of adult returns from released smolts. By retaining fish at the hatchery for a longer period of time hatchery personnel are able to release higher quality smolts into Young’s Bay and Blind Slough.
The 15 low head oxygen units supply oxygen to each pond and are powered by six small oxygen generators. As water passes through each pond, a new dose of oxygen is added to maintain the appropriate levels for sustaining fish throughout the year – particularly during low water periods.
“When this water passes through a pond of fish, the oxygen is depleted. We replenish the oxygen when the water goes into the second and third ponds,” said Gnat Creek Hatchery Manager Roger Warren. “We are effectively reusing the water two more times after we initially pass it through the first pond.”
The low head oxygen system is more efficient and easier to troubleshoot compared to other systems. Each pond is run separately so if one of the systems breaks down, the rest of the ponds continue to receive oxygen. Other systems are comprised of one big component that provides oxygen for all of the ponds at the same time. If the big component malfunctions, all of the ponds are without oxygen.
The project was made possible by a $108,000 grant from the Oregon Department of Fish and Wildlife Restoration and Enhancement Program. Gnat Creek Hatchery is located 18 miles east of Astoria on Highway 30.