Not all native fish are truly native. It is a gross oversimplification to assume that a brook trout in a New York stream is part of an unbroken line of char going back millennia. Although a watershed or an individual river may have historically contained a particular species of fish, there are numerous reasons why the fish now present are more recent residents. Stocking, migration, and weather events can all alter native fish populations. The only way to discern these changes is through genetic analysis.
Genetic analysis is often the only way to reliably identify individual strains, or populations within a trout species. Anglers are able to tell the difference between different species of trout through coloration or pattern. Within a species, those aesthetic differences aren’t always as significant when trying to determine strains.
Spots, stripes, and hues are not generally reliable indicators among brook trout populations. They might reflect water chemistry or the coloration of the stream bottom, but a dark fish in one creek may very well be of the same strain as a lighter-bodied fish in an adjacent creek. Interestingly, another lighter-bodied fish found far upstream in the latter creek may be genetically distinct.
How is this information gathered, and why is it relevant to the angler?
Trout Power is a nonprofit that utilizes citizen science efforts seek to identify, map, monitor and advocate for protection of wild and genetically unique brook trout populations in the Adirondacks and wherever they are found throughout New York. With a tissue sample as small as a fin clip and demographic data from where it was collected, important information can be added to a growing database about native fish. The samples are analyzed at university laboratories and compared against other samples at the stream, watershed, and species level. What is coming together through the efforts of Trout Power and its partners is a detailed and complex picture of the eastern brook trout.
The science is complicated in some respects; in others it is not very different than understanding how a poodle, a labradoodle, and a wolf are genetically related to one another. The relevance is something that is not complicated at all. The more we know about distinct fish populations, the more we know about ecosystems. This establishes a clear baseline for what constitutes natural – what the aim of conservation ought to be.
The brook trout of Honnedaga Lake were thought to have been wiped out by negative impacts of acid rain in the 20th century. About 25 years ago, Cornell biologists began to find brook trout in the lake outlet. Investigation revealed that while the population had indeed be impacted by pollution, the fish retreated to deep cold water seeps. As far down as 80 feet, these small char lived in clean pockets of water. A homogenized, hatchery raised brook trout would not solve the problem of a recovering lake – it would hurt the heritage strain that was prepared to make a comeback.
This single, localized example of how comprehending genetic distinctives illustrates the value of work like that of Trout Power. Taking a micro-level view of a macro-level problem allows for nuanced solutions and a comprehensive understanding. By leaning on the initiative of anglers, students, and environment-conscious people willing to find a fish and clip a fin, efforts can move across the range of brook trout at a grassroots level. These efforts might lead to exciting discoveries. They may also simply inform the best way forward to protect and restore native fish. Which, of course, is certainly exciting as well.
Find about more about Trout Power here. Contact them to see how your TU chapter, your homeschool co-op, or your watershed organization can begin genetic analysis of your brook trout.