Aquatic Life: Fish

Anyone who has ever baited a hook and sat on the riverbank or in a boat can tell you about the sheer ecstasy of fishing. Anglers’ study the habits of the fish they are seeking and know what bait will catch the big lurkers that get mounted and displayed on the wall. Most anglers however, do not know how water quality affects their favorite swimming hole or why certain fish are in certain places.

Certain species of fish are highly adaptable. They can live in almost any kind of aquatic environment. Others are adapted to a specific type of environment and any change to that environment reduces their chances of survival. Catfish for example, are fairly adaptable. They are typically a bottom-feeding species and are not greatly affected by sediment and low dissolved oxygen levels. In fact, it seems that catfish are more active when streams are muddy. Shell crackers (bream, bluegill, crappie, largemouth bass, and small mouth bass) prefer higher quality waters. These fish generally thrive where there is a fairly substantial invertebrate smorgasbord that can tolerate warmer water and moderate oxygen levels. Trout on the other hand are the least adaptable of the species we have here. Trout must have high quality waters to reproduce and survive.

If you have fished much in the Rocky Broad River, you will know that there are three species of trout that are stocked in our waters: brown, rainbow, and brook. The brook trout is the only native trout species to eastern North America. Brown trout were introduced from Europe and rainbow trout are native to western North America. The speckled trout is typically considered to be a subspecies of the brook trout but they are increasingly rare and are limited to high elevation streams where water quality is premium.

Inland trout species require excellent water quality. They cannot tolerate high levels of sedimentation, chemical pollution, or low dissolved oxygen content. High levels of sediment cover the cobbles and stones that are essentially the spawning grounds for trout. This sediment also reduces the amount of substrate to which many invertebrate species attach themselves and provide a food source for trout. Higher sediment levels result in reduced visibility, making it more difficult for trout (a sight predator) to locate food. Sediment also reduces the water’s ability to carry dissolved oxygen and actually warms the water temperature.   Warm water does not carry oxygen as well as cold water. Chemical pollution prevents oxygen exchange through the trout’s gills and causes sores and disease that kills fish. The Pigeon River is a good example of a river that was almost destroyed because of chemical pollution. Thanks to the efforts of some organizations like the Upper Broad River Watershed Protection Program, the Pigeon River supports trout again.