Moosehead Lake Region fishing report

By Tim Obrey, regional fisheries supervisor

If you are a frequent reader of these fishing reports, you may recall some of the work we have done on Rainbow Lake to keep landlocked salmon out of this Arctic charr water. We typically think of bass, crappie, and pike when we talk about invasives in Maine. But salmon are not native to Rainbow Lake and any type of competition with the native charr is bad news.

When we had substantiated reports of salmon in Rainbow Lake, we knew we had a serious problem. Salmon have been present downstream in the drainage since the turn of the century, but we never had reports of them reaching Rainbow Lake. The water conditions must have been just right at some point in the past few years to allow young salmon to pass up this steep stream. To make matters worse, the old driving dam on the outlet of Rainbow Lake that had been an impasse to fish passage, was in disrepair. Once salmon passed the natural obstacles downstream, there was nothing to stop them from getting in the lake.

We assisted in the construction of a new dam and barrier on the outlet of Rainbow Lake in 2018-20. There were no maintained roads to the lake, so about three miles of the old Rainbow Lake Tote Road had to be reopened enough to get an excavator and materials to the site. It was quite an endeavor!

We returned to the lake this September to inspect the dam and to electrofish one of the tributaries to Rainbow Lake. The outlet of Doughnut Pond flows into Rainbow Lake, and it’s the only tributary that has suitable spawning and nursery habitat for salmon. Salmon require gravel areas for spawning and young salmon will reside in the stream for two years after hatching. They prefer boulder and rock habitat during this period. There are not many tributaries to Rainbow Lake, and we examined all of them a few years ago. At that time, we felt the outlet of Doughnut Pond could support salmon reproduction and pose a threat to the charr population in Rainbow Lake. 

We flew into Rainbow Lake in September with Warden Pilot Chris Hilton and electrofished the stream looking for young salmon. We were pleased that we did not find any. There were a few minnows and some young brook trout in this boulder-strewn stream. In addition to the threat salmon pose, we now have smallmouth bass in Nahmakanta Lake which is directly downstream. We remain hopeful that the new barrier will protect Rainbow Lake from the undesirable fish that are present downstream.  

Invasive fish are the most serious threat we have to our coldwater fisheries in northern Maine. It is vital to maintain barriers, like the one constructed on Rainbow Lake, to protect our wild and native fisheries. Once these populations are gone, there is little chance to ever recover them.

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