Tracking Brook Trout

        At Breakheart Brook in the Arcadia Management Area in Exeter, Ellie Madigan bushwhacks along the edge of the stream carrying a hand-held antenna and receiver to listen for an electronic beep that indicates a brook trout is nearby. During a half-mile of walking, she hears only the sounds of the gurgling brook, a few songbirds, and the buzzing of insects. So she heads in the opposite direction.
        Madigan, a University of Rhode Island student, is joined in the search by fellow student Mitchell Parizek and Corey Pelletier, a biologist with the Rhode Island Department of Environmental

DEM biologist Corey Pelletier and URI students (M. Derr)

Management, who devised the research project to track the movement of the state’s only native trout species. After capturing 75 trout in May and implanting a tracking device in each of them, Pelletier, Madigan and Parizek are trying to relocate each of the fish every week throughout the summer to figure out where the fish go as water temperatures rise.
        “One of the things brook trout need for survival is cool water during the summer and high levels of dissolved oxygen,” said Pelletier. “That dictates the habitats they can spend time in and survive in. But often there are significant numbers of impoundments — dams dating to pre-industrial times that not only inhibit trout movement but also warm up the water.
        “One reason why we find brook trout in these small streams is because the streams are often fed by groundwater — whether through seeps in the woods or seeps that come through the streambed — and groundwater is cool and contains enough oxygen,” he added.
        Most of the state’s small number of brook trout are found in the Wood-Pawcatuck watershed in South County, so that’s where Pelletier and his team are spending most of their time.
        Brook trout are considered “a species of greatest conservation need” in Rhode Island. They typically grow no larger than 12 inches, and often only 6 to 8 inches, because their limited habitat in small streams keeps them from growing larger. The chief threats they face are changing environmental conditions – mostly warming waters and low dissolved oxygen – as well as pollutants due to run-off from nearby developments. Stocked trout are also a concern, since they are usually non-native species that are larger than brook trout and can outcompete the native species for food and habitat.
        That’s why the state will no longer be stocking trout in the Beaver River, and fishing there will be limited to catch-and-release only to create a stream specifically managed for wild brook trout. Last year the state also increased the minimum size of trout that can be harvested in Rhode Island waters to eight inches, which means that most brook trout will have to be released if caught.
        Charlestown resident Jim Turek supports these efforts to protect brook trout and their habitat. An enthusiastic trout fisherman who has little interest in catching stocked trout, he calls brook trout an iconic species for New England.
        “They’ve always been here, and they’ve sustained local communities for centuries as a source of food and enjoyment,” he said. “It’s a heritage fish that looks better and tastes better than trout grown on food pellets in a hatchery.”
        Turek is one of dozens of Rhode Island trout fishermen who are committed to protecting the species and who are strict about not revealing the location of their favorite trout streams.
        “We believe we should do all we can to save these fish,” he said. “Brook trout populations are so small that if we tell the public where to go fish for them, they’ll remove some of the bigger ones and we won’t have a sustainable population any more. We’re happy to just walk along a stream and see a beautiful fish and know they’re still there. We don’t even need to catch them.”
        Even among the fishermen there is disagreement, mostly about the most appropriate fishing method for catching brook trout. The fly fishermen say that using flies is less likely to cause injuries to the fish that could lead to their death, enabling the fish to be released unharmed. The bait fishermen disagree.
        Pelletier isn’t taking sides. He’s mostly interested in learning as much as he can about where the trout go in summer so those areas can be protected from development and fishing pressure and to figure out how to keep the water temperature in those locations from getting too high.
        “The optimal water temperature for brook trout is 12 to 18 degrees Celsius, because that’s when they exhibit their highest growth rate, but above 18 you get into stressful conditions for them,” Pelletier said. “Above 23 and they don’t exhibit positive growth, and above 25 is potentially lethal, but it depends on how long they’re exposed to those temperatures.”
        His tracking study ran into difficulties immediately after the tagged fish were released in May because a stretch of hot weather in early June forced the fish to move much farther than Pelletier expected.
        “Wherever they were in May is now too warm for them, so they’ve had to go somewhere else,” he said. “But it seems like when temperatures are suitable, they can remain in the same spot for weeks.”
        Back at Breakheart Brook, the research team found just two tagged brook trout by the end of a long day of tracking. But they weren’t discouraged. They had many more miles of shaded streams to search to find the heart of the brook trout’s summer range.
        “The information that comes out of this study will be very important for the future management of this species,” Pelletier said. “We’ll understand the areas necessary to support trout through the very stressful high-temperature periods. It’s going to give us insight into management actions we can take to further protect the species.”

        This article first appeared in the August 2021 issue of South County Life magazine.