A 2016 file photo of the Penobscot dam. Credit: Gabor Degre / BDN

The illegal introduction of invasive species poses a serious threat to the health of existing native fish populations in Maine’s lakes and rivers.

In some places, illegally placed fish such as northern pike have wiped out existing populations of coldwater game fish, overtaking the lakes where they were introduced, and have quickly spread to adjacent waters.

Making sure that doesn’t happen in some of the state’s most prized landlocked salmon and brook trout fisheries in the Penobscot River watershed is the aim of LD 1049.

The intent of the bill, sponsored by Sen. Russell Black, R-Wilton, is to amend existing laws to prevent the future installation of a fishway at the Penobscot River dam in Medway and the removal of the four-foot barrier at the Brown’s Mill Dam on the Piscataquis River in Dover-Foxcroft. Fishways are channels built into or alongside dams that allow fish to move past the dam and into the river above.

Proponents of the bill want to make sure northern pike and other invasive fish cannot make their way farther upstream into prime salmon and trout habitat.

“Simply put, if sometime in the future fish passage is provided at the Medway Dam the entire West Branch of the Penobscot River would be at risk for invasion by Northern pike,” Nels Kramer, a former 36-year biologist with DIF&W, said in what will be his testimony before the Committee on Inland Fisheries and Wildlife when it holds a public hearing on the bill.

Baxter State Park also is located within the watershed of the West Branch of the Penobscot River, making the issue even more important, he said.

“Some of the best fishing for landlocked salmon in the State of Maine occurs in the West Branch, and all the lakes associated with that storied drainage, including Pemadumcook Lake, North and South Twin Lakes, Ambajejus Lake, Millinocket Lake, First Debsconeag, and all the JoMary Lakes,” Kramer said.

Concerns about invasive fish movement were magnified as a result of discussions stemming from the relicensing process being conducted by the Federal Energy Regulatory Commission on dams along the West Branch of the Penobscot.

Kramer said it has been suggested that passages be installed at the dams, or that some of the dams be removed, to facilitate the upstream passage of alewives and shad. He stressed that there is no Atlantic salmon Critical Habitat, as defined by the National Oceanic and Atmospheric Administration, above the Medway Dam, which is the last line of defense preventing pike, white catfish and other invasives from getting upriver.

He also noted that if all barriers are removed on the Piscataquis in Dover-Foxcroft and Guilford, invasive species will decimate the wild native brook trout populations in the upper Piscataquis River and will allow them to get precariously close to Moosehead Lake.

In 2003, illegally introduced Northern pike were discovered in Pushaw Lake, located just north of Bangor. The voracious predators have already made their way into the adjacent Stillwater and Penobscot rivers.

Pike have been documented moving through the fishway at the dam in Milford and now have access all the way to Medway on the Penobscot, and to Dover-Foxcroft on the Piscataquis.

Efforts by the Penobscot River Restoration Project, which previously removed several dams and barriers on the Penobscot, included the addition of a fish passage channel at the dam in Howland. Those projects, designed to restore upriver access to native sea-run fish, with a focus on the endangered Atlantic salmon, sea herring and shad, also opened the door to invasive species.

The dams at Medway on the Penobscot River and Brown’s Mill on the Piscataquis River are the last remaining barriers to prevent pike from having access to important fisheries habitat. Those include salmon and trout waters in the Millinocket region, and Sebec and Schoodic lakes on the Piscataquis.

Sebec is one of Maine’s four original landlocked salmon lakes.

LD 1049 has been referred to the Committee on Inland Fisheries and Wildlife, which is expected to hold a hearing on the bill during which it will hear public comments.

Pete Warner

Pete graduated from Bangor High School in 1980 and earned a B.S. in Journalism (Advertising) from the University of Maine in 1986. He grew up fishing at his family's camp on Sebago Lake but didn't take...