Lake Trout Broodstock Clear Waivers and Head North
BY DOUG ALOISI, GENOA NFH
The first year class in what is hoped to be a long line of wild originated broodstocks cleared their last fish health exam in the newly renovated quarantine facility at the Genoa National Fish Hatchery (NFH). The Genoa hatchery runs a wild fish quarantine facility, which brings the eggs of wild fish into the hatchery and quarantines them from the general fish populations housed at the hatchery. The fish are then tested for diseases that affect both hatchery and wild fish to determine if they are "clean" from those communicable diseases. This process takes a total of 18 months, and three fish health examinations.
Collecting the broodstock to develop a new brood line of fish that genetically represents the wild population is no easy task. Over 100 fish are collected at a time, usually over the range of the fish's spawning season, which can be as long as two months. Then the eggs are kept separately by parental matings until just before hatching. At this point, mortality is roughly equal between pairs, and the numbers of eggs are equalized by mating to ensure equal genetic contribution. Then they are combined into tanks.
After eighteen months of careful culturing and a clean bill of health the brood “lot” is moved to one of the Fish and Wildlife Service’s captive broodstock facilities such as Iron River NFH in Iron River Wisconsin. Here they will hopefully produce many years and many millions of eggs to restore native populations of lake trout and coaster brook trout in the Great Lakes watershed. This spring a Klondike Reef strain of lake trout was successfully cleared from the quarantine facility and has been transferred to the Iron River hatchery. Recent improvements to the quarantine facility include filtering and sterilizing systems to ensure that no fish diseases that may have been brought into the quarantine facility will leave the facility inadvertently through hatchery drain water. Drain or “effluent” water is filtered and sterilized with ultraviolet light to kill microbes that may be present in the hatchery water before it leaves the building. Soon the facility may be expanded yet again to make way for other imperiled species such as lake sturgeon and Great Lakes herring species. The new renovations were made possible by the recent passage of the Great Lakes Restoration Initiative, legislation enacted by Congress for the restoration of native species and their habitats in the Great Lakes basin.