May 29, 2026
Alice Hotopp – Fisheries Assessment and Science Communication Specialist, Downeast Salmon Federation
Hello! My name is Alice Hotopp, I’m the Fisheries Assessment and Science Communication Specialist at Downeast Salmon Federation (DSF). You may have seen me along the Narraguagus or having a coffee at the Paisley Loon. Ellie Mason, DSF’s Habitat Restoration Project Manager, and I will be bringing you updates about the construction project at Cable Pool Park on this page—check back in here throughout the summer and fall.
The first week of construction has arrived! We are excited to be on the verge of breaking ground on this project that will allow the Narraguagus to flow free and bring new features to the park. This moment has been years in the making—thank you to our many project partners and members of the Cherryfield community for their support.
One of the driving goals of replacing the ice control dam with a nature-like fishway is to improve passage for sea-run fish. In fact, the engineers that designed the dam used data on fish physiology and behavior to help design the fishway. But, after construction is complete, how will we know if we’ve achieved our goal?
In a project started this spring, DSF is using a tool called environmental DNA to help determine if the nature-like fishway has improved fish passage.
Assistant Hatchery Manager Ben Huott tending our eDNA sampler.
Currently, the sea-run fish of the Narraguagus can swim unobstructedly to the pool below the Cherryfield Ice Control Dam. There, fish like shad are often observed milling around in the pool, looking for a way to keep moving upriver. Some of these fish will eventually find the fish ladder built into the east wall of the dam, but some will give up and swim back downstream. The ones that do find the ladder may have taken hours, or even days, longer to swim upriver than they would have with nothing blocking the river.
As fish, or any organism, move through their environment, they are constantly shedding their DNA. This DNA, called environmental DNA (eDNA), can come from skin cells, mucous, feces, and gametes that are cast into the water as the fish swim and go about their business—yum, right? Water samples collected from the river therefore hold fish DNA, which can then be analyzed in the lab to help determine relative abundances of fish species located in different parts of the river.
This spring, DSF has been collecting eDNA samples both above and below the Ice Control Dam. We hypothesize that, before the dam is removed, there will be a higher concentration of fish DNA below the dam than above, reflecting the larger numbers of fish below the dam and smaller numbers of fish that successfully make their way above the dam. We will repeat this study next spring when the nature-like fishway is in place, when we expect to see roughly equivalent eDNA concentrations above and below the fishway. We are focusing specifically on American shad and sea lamprey—American shad because they are known to be the least capable of swimming through the ladder; sea lamprey because they help create Atlantic salmon spawning habitat upriver and bring marine-derived nutrients to riverine ecosystems.
As the season progresses we will bring you periodic updates on our research and other project happenings.