The Glacier watershed hosts about one-third of the natural lake habitat for bull trout in the country, but the fish themselves are increasingly scarce. Not only must they contend with lake trout, which consume native fish and compete with them for nutrients, now rising temperatures could soon make the water too warm for the cold-loving bull trout to spawn. Counts are so low that they’re listed as threatened under the Endangered Species Act.
The Judas fish has been a blessing for the bull trout of Quartz Lake. Over the five years of the project — the intensive phase wrapped up in 2014 — the team hauled more than 2,000 lake trout out of Quartz, finding fewer each year.
The native bull trout population is exploding, with more nests and some of the highest spawning counts on record.
“We got there in the nick of time,” Muhlfeld says.
But the battle isn’t over. In many other areas, lake trout are still winning.
A Watery Haul
The team has now set its sights on Logging Lake, in another area of the park. It poses an even bigger challenge than Quartz: Here, lake trout have already taken over, and there are few bull trout left. The Judas fish alone won’t be enough.