Brook Trout Study - A Volunteer Opportunity and Piece of a Bigger Puzzle
Some coastal brook trout spend all their lives in fresh water. Others head out to sea for a few months or a year and then return to fresh water to spawn. The ones that move back and forth are called “salters” or “sea run brook trout.” The technical term for this movement out to sea and then back to fresh water for spawning is “anadromy.” Nobody knows why some brook trout are anadromous and others are fresh water residents all their life. Biologists do believe, however, that the number of anadromous fish is declining. They are not sure why, but roads and culverts blocking the movement of the fish are one possible factor, among others.
As is the case with so much other ecosystem research in and around Acadia National Park, the first step toward understanding the bigger questions is an assessment of the current situation. How many fish are moving back and forth? Where does the migration happen? Where does it NOT happen?
We have received a flyer from Maine Inland Fisheries and Wildlife that describes an assessment program that involves volunteer anglers. (We have put a copy of the flyer here on our website.) If anglers send Maine IF&W a small sample of the scales of brook trout caught in coastal rivers, they can help the State researchers create a map of where the brook trout are still moving back and forth between fresh water and the sea. Contact information about the program is in the flyer. We have also used our website to provide a list of the streams and rivers, sorted by location, where Maine IF&W would like to collect data. All of the streams on MDI are on the list, as are numerous streams in Blue Hill, Franklin, Gouldsboro, and other area communities.
The assessment information opens the doors to other questions about sea run brook trout. For example, research is currently underway in Massachusetts that looks at issues such as how road crossings and culverts affect the movement of brook trout back to their spawning grounds. With sufficient understanding of populations and movements, researchers can look at the affects of different stressors and combinations of stressors on spawning, foraging ability, and survival. As one scientist put it in a recent phone call on the topic, "The question that we want to answer is ‘What makes a successful fish?’"
This is one instance of a broader set of questions that confronts the Park. That broader set of questions grows from the fact that Acadia National Park is relatively small in area, and so is dependent upon the land and streams around the Park to sustain the diversity of species in the Park. We know that much of that surrounding land will be developed over the next 25 to 50 years. What we don’t know is how different kinds of development will affect the movement of plants and animals around the area, from the Park to the surrounding area and back. How do we design culverts, road crossings, and other development to maximize that movement? How do we preserve the "permeability" of the landscape over time, so that life continues to move through it?
Understanding sea run brook trout–what factors trigger anadromy–and then understanding how to manage the landscape to preserve the possibility of anadromy–is one important piece of that bigger puzzle.
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