The following  Questionnaire will assist you in determining what types of stewardship and recovery strategies relating to aquatic species are the most applicable for your property.

In addition to non-aquatic species, riparian corridor are obviously home to many aquatic species as well. Unique to stream corridors and other bodies of water, aquatic species can thrive under the right conditions. Land use, water quality, stream features and biology are just some of the factors that influence a healthy fish community. Recognizing what makes a healthy fish community can help you protect and preserve it. Below, you will learn about what contributes to a high quality aquatic species habitat, as well as what to look for on your property. You will also learn about some of the more common aquatic species that live in the Lefthand, Big Thompson, Little Thompson and St. Vrain watersheds.

High Quality Aquatic Habitat

High quality aquatic habitat is comprised of a number of factors. An important item to consider is that aquatic habitat refers to much more than just fish. Aquatic habitats also support insects and non-aquatic animals as well. In fact, many insect species begin their life cycles in the water. The primary factors of high quality aquatic habitat are:

Connectivity

While non-aquatic organisms rely on a network of patches and corridors for habitat, aquatic habitat connectivity is more straight-forward. Fish and insects need to be able to move upstream and downstream in order to thrive. If there are barriers to this movement, the organisms will be confined to a limited area for breeding, feeding and shelter. As a result, this will also limit their population.

Complexity of Habitat

A key to aquatic habitat quality is the complexity of the stream itself. Higher quality stream habitats will have a variety of bank edge conditions, bed material and in-stream features like boulders, riffles and pools. This variety will provide areas for fish and insects to feed, hide from predators and breed.

Cover/ Shelter

Cover in aquatic habitat can take multiple forms. Willow plants growing along the streambanks can often provide cover for fish to hide from predators. The willows also shade the water, which cools the temperature during hot summer days. Dead woody material also provides valuable cover and shelter for wildlife. Boulders and deep pools in the river can also provide cover/ shelter for fish. Insects will use rocks of many sizes as shelter.

Water Quality and Water Quantity

For many aquatic organisms such as fish, the stream water is their entire habitat. It is a confined area that can be heavily impacted by the surrounding activities. Because of this, fish and other aquatic organisms can be very vulnerable to detrimental activities next to or along streams. Pollutants such as fertilizers, oils or pesticides can quickly kill off large fish populations. Similarly, a blockage in a stream can cause low flows downstream. While seasonal fluctuations are normal, an irregular/drastic low flow can cause the water temperature to rise and algae to grow very quickly. This can then cause a dramatic reduction in the amount of oxygen in the water. All of these changes impact the aquatic habitat and can cause large fish die-offs.

Common Aquatic Species

The following pages contain information about some of the more prevalent aquatic species in the Lefthand, Big Thompson, Little Thompson and St. Vrain watersheds. Fish species can vary greatly depending on elevation, stream temperature and general environment. Many aquatic biology books and resources will group Colorado fish species into mountain region species and plains region species. Colorado Parks and Wildlife has online identification guides for fish species, as well as aquatic insects. Both can be very useful for anglers and landowners (links at right).

CPW Identification Guides:
Fish
Insects

Often found in high mountain lakes and streams, trout are a favorite among anglers in Colorado. There are many prevalent species of trout in Colorado, including Brook, Brown, Cutthroat, and Rainbow Trout. Cutthroat Trout are the only species native to Colorado, with a number of subspecies found throughout the state. While most trout thrive in the cold water of mountain streams and lakes, Brown Trout can also be found in larger rivers flowing onto the plains.

Photos courtesy of: Ben Swigle, CPW


Plains fish, usually in a warmer ecosystem, comprise of a variety of fish, including bass, carp, bluegill and smaller species such as chubs, suckers, dace and darters. The Longnose Sucker can sometimes be seen in mountainous streams as it prefers colder waters. The Longnose Dace, chub species and the darter are smaller fish found exclusively along the plains. Most of these are not considered game fish (fish that anglers try to catch), although some such as bass and bluegill are. All of them thrive in areas with shaded streambanks and woody debris.

Illustration courtesy of: Ellen Edmonson

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