Invasive Crayfish

                                                                                   Thom Hulen, DFLT Conservation Director                        
 

Seven Springs, northwest of the towns of Cave Creek and Carefree, is a wonderful example of how Sonoran Desert streams should look. Similar to the Desert Foothills Land Trust's Jewel of the Creek Preserve, there are the crucial five riparian trees that define the Sonoran Riparian Deciduous Woodland Community. Velvet ash, Wright's sycamore, Goodding's willow, Fremont cottonwood and Arizona walnut thrive under the wet conditions. Living in the stream are several kinds of fish and aquatic insects. Presently there are two native fish species found here and possibly four exotic species such as large mouth bass, green sunfish and fathead minnows.

Another aquatic species thrives here that like the exotic fish was not part of the original community. This animal is the crayfish. There is no native crayfish in this state. Originally brought to Arizona as forage and bait for game fish such as bass, crayfish have spread to most of Arizona's aquatic systems. In addition, some populations may have been established to provide an easily obtained and sustainable food force for people who eat crayfish, which are quite delicious boiled and dipped in drawn butter and lemon or smothered in hot sauce.

As with everything people do there are unintended consequences. The problem with crayfish is that they are voracious consumers and breeders. They eat just about anything, both plant and animal, including each other. Prolific consumers, an unchecked population of crayfish, which have few or no predators, can render a small stream into an aquatic wasteland almost devoid of life leaving only a layer of brown silt on the streambed.

Crayfish have been implicated as a serious threat to Mexican garter snakes, Chiricahua leopard frogs and other threatened or endangered species in the Southwest.

Controlling crayfish infestations is problematic because agents used to kill them are dangerous to non-target species. Removing them by hand or by traps has the least effect on non-target species, but is time consuming and ineffective at reducing crayfish populations.

Fortunately, the Desert Foothills Land Trust's preserves bisected by Cave Creek have zero to few crayfish. In the three-almost-four years I have worked for the DFLT I have encountered only one live crayfish at the Jewel of the Creek Preserve and only one exoskeleton at the Watt Preserve. Why the DFLT preserves have so few and Seven Springs less than fourteen miles upstream is overrun I do not know. It is important that DFLT monitor its preserves and take decisive action before any invading crayfish can do damage.

If you are interested in eating crayfish and want to learn how to effectively catch them and cook them contact the Arizona Game and Fish Department. They have a helpful brochure that will answer all your questions. If you decide to bring some home to eat please remember that it is illegal in Arizona to transport live crayfish.

For more information about crayfish in Arizona contact the Arizona Game and Fish Department at 22221 West Greenway Road, Phoenix, AZ 85023, 602.942.3000, www.agfd.com