Unanticipated, negative effects of stocking nonnative fish are such a commonplace occurrence that fishery scientists have dubbed the phenomenon the “Frankenstein Effect” (Moyle et al. 1986)

photo: Alaska Dept. Fish and Game

NORTHERN PIKE

The northern pike (Esox lucius) is  number one on many states’ lists of illegally stocked predator fish.  That’s no surprise- they get big, they’re fun to catch, and they’re hardy (so they are easy to transport). Unfortunately, illegally stocked pike populations are ravaging wild trout and salmon stocks in Alaska, native fish in the Colorado River basin, and sustainable sport fisheries all over western North America.

YELLOW PERCH

Yellow perch (Perca flavescens) is the second most commonly stocked illegal fish in western North America. Unfortunately, the outcome of these plants is often tragic: in Montana, 90% of illegal perch fisheries end up stunted, but not until they’ve ruined the existing, often times excellent fisheries. A similar outcome has been reported in Alberta.

At Blue Mesa Reservoir, CO, illegally stocked yellow perch are costing the state $125,000 annually in increased kokanee stocking, and the perch population is still growing rapidly.

modified from USDA photo

photo: UK Daily Mail, by Andrew Alder

SNAKEHEAD

Snakeheads (Channa spp.) are native to southeast Asia and Africa. They have been imported to the U.S. as aquarium fish and for the live food fish trade. Intentional introductions of four species have occurred throughout the U.S. and fishery biologists have captured wild individuals in California, Florida, Hawaiii, Maine, Maryland, Massachusetts, Rhode Island, Virginia, and Wisconsin.

Snakeheads compete with native aquatic wildlife at all life stages, but adult snakeheads are voracious predators consuming all sorts of fish, crustaceans, amphibians, reptiles, and even birds and small mammals. Experts believe these fish pose a significant threat to fish and wildlife resources of North America.

photo: Alaska Dept. Fish and Game

BURBOT

The burbot (Lota lota), ling, eelpout, or lawyer as they are sometimes called, is actually a freshwater cod native to northern latitudes, worldwide. While they are native to parts of Wyoming east of the continental divide, they were recently illegally transplanted into Fontanelle Reservoir in the Green River drainage of southwestern WY. There they spread into rivers throughout the drainage and appear to be decimating native nongame fishes.

The fish also invaded Flaming Gorge Reservoir where they are jeopardizing world class kokanee and lake trout fisheries, as well as posing a hazard to endangered fish downstream of the reservoir. Only time will tell how the “Frankenstein Effect” will play out in this high stakes venue.