Acid Rain Threatens Brook Trout

If the largemouth bass is a bait-caster’s fish, then the brookie belongs to the fly fisher.

As their name implies, brook trout are at home in the stream. Their native range extends from tiny streams of north Georgia, through the Appalachian Mountains, to the large rivers of Labrador, and then westward through the Great Lakes drainages. The brook trout is the only trout native to the streams that fill the Great Lakes. While they do have a strong affinity to flowing water, a strain of brook trout, called coasters, has adapted to the nutrient-rich coastline, and estuaries of the lakes. This strain grows larger and faster than the stream-bound fish, but that may have less to do with genetics than differences in their environment.

Craig Springer

The brook trout is actually no trout at all. It is a member of the salmon family as are the trouts, salmons, and pikes. But the brook trout, and the lake trout, are actually chars. Chars differ by having light-colored spots on top of a dark background. It is just the opposite for trout and salmon. Another not readily discernable difference is the amount of teeth; char have extra teeth in the roof of the mouth, a feature that allows for gripping food.

Food preferences depend on two things: size of the fish and time of the year. In the warm months, the favored fare seems to be insect life. Caddisflies, mayflies and blackflies are heavily fed upon, as are stoneflies, both in the nymph and adult stages. Snails are also eaten, but only in the absence of abundant insect life. Outside the warmer months, larger fish will eat frogs and other fishes. Lake-dwellers especially have shown an affinity toward mud minnows, small sunfishes, and yellow perch. Shrews and mice have also shown up in brook trout stomachs. Fortunately for the brook trout angler, this species has a very short intestinal tract meaning it quickly digests food. The quicker it digests, the more frequently it eats, and the more it eats, the sooner it is to rise on an imitation insect.

Life for the brook trout starts in the pea-gravel riffles in the little mountain brooks. At the same time the Appalachian maples, beech, and oak leaves turn scarlet, orange, and yellow — the same colors sported by brook trout — adult brookies are making short upstream forays to find spawning habitat. Females clear gravel of sediment and debris while the males vie for the attention of the ladies, sometimes locking jaws in fights.

Assuring the greatest genetic diversity in habitats populated with few members, the females breed with several males over the short spawning season. This prevents inbreeding and in the end a robust population. After the spawn the adults descend to deeper water. The eggs are left to fend for themselves all winter. Lake-dwellers move up rivulets and rivers to spawn; others may move onto shoals. Females drop up to 5,000 orange-colored eggs. They incubate in 150 days, hatching in early spring; the young soon set about eating plankton and crustaceans.

Acid rain is still a problem in native brook trout habitat, particularly in the upper Appalachians.

By trout standards, brookies live a long time — up to 12 years. Though voracious they may be, they don’t get to the huge sizes of their next of kin. The biggest brookie on record, a 14-pounder, was landed from the Nipigon River in 1916. Today, one of a few pounds might have some cracking open the phone book for a taxidermist.

Though brookies only naturally occur in the East and Midwest, they have replaced native cutthroat trout in many places in the West. The brook trout has been reared in hatcheries for a long time, which has facilitated their spread. But it is a curious artifact of the modern age that in the West, brook trout have taken well to novel habitats — to the detriment of native species — but in the East where they naturally occur, they stare trouble squarely in the face. That is due in part because trout from the West, rainbows, have replaced them in their native haunts.

Another problem is acid rain. Acid rain was always in the headlines 20 years ago, but not now, and not much has changed. Acid rain is still out there and still a problem in native brook trout habitat, particularly in the upper Appalachians. And wild brook trout populations in the George Washington National Forest in Virginia have taken a hit. About 10 percent of Virginia brook trout streams are severely acidic and nearly half are considered vulnerable to acid rain. The acidic waters cause naturally occurring aluminum to come out of the bedrock and mix with the water. The aluminum creates gill problems in trout and kills aquatic bugs, the trout’s food source.

Researchers at James Madison University are seeking remedies. They recently poured limestone sand into the headwaters of an afflicted stream, Fridley’s Run. The tiny brook was seeded with 91 brook trout. Four years later, thousands of fish swan the stream and the insect life returned.

But this is only a Band-Aid approach to a gaping wound. Acid rain is still out there and brook trout are still vulnerable.

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When not penning stories about the outdoors, Craig works in communications for the U.S. Fish and Wildlife Service. He is an outdoors’ columnist for the Albuquerque Journal and ESPN Outdoors, and a frequent contributor to Flyfisher and North American Fisherman magazines. He holds degrees in fisheries and wildlife management from Hocking College and New Mexico State University, and an M.Sc. in fisheries science from the University of New Mexico. He’s a candidate for an M.A. in rhetoric and writing at the University of New Mexico. He writes weekly for sportsmansguide.com.

 

 

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