Above: Lake trout eggs in Yellowstone Lake. Below: Native cutthroat trout spawning in Yellowstone. Photos by NPS Jay Fleming
November 2014: The fish battle continues in Yellowstone. For the last two decades, Yellowstone has been trying to get non-native lake trout under control so that its once abundant native cutthroat trout can make a comeback. The problem is that lake trout live to an old age of 25-40 years. Once they reach four-years-old, they begin eating cutthroat trout. The native fish becomes up to 50% of their diet.
Earlier this autumn, Yellowstone poisoned some streams to kill the pesky fish and reestablish cutthroat.
In Yellowstone Lake, the preferred method of ousting the fish was using a gill-netting boat. This method has removed 10’s of thousands of fish from the lake but the procedure has been called a “forever project” because the job is never done.
Last week, Yellowstone began an experimental process of electrifying spawning beds in Yellowstone Lake. Park fisheries supervisor Todd Koel told the Jackson Hole News, “The two tools that we used are still prototypes. One of them is electroshocking. It’s an array that you move along the bottom. The electric grid, about 10-feet by 20-feet, is dangled from a boat and cranked up to 600 or 700 volts,” Koel said. “It’s held in place for a minute or two and then boated to the next place.
“The other tool that we have,” he said, “it’s a placer gold mining suction dredge system.”
In summary, Yellowstone electrocutes lake trout eggs and then sucks them out of cobble at the lake bottom. Initial results are promising. More dead eggs are being vacuumed up than previously, without the shocking process.