Signal crayfish
Pacifastacus leniusculus · Aquatic life
Whole animal · Photo: Parsa Fard / CC BY
Also called Crawfish, Pacifastacus, Crawdad
How to identify Signal crayfish
- Large crayfish up to about 6 inches
- Smooth claws with a white to pale blue patch at the joint (the signal)
- Brown to olive or reddish brown body
- Underside of claws reddish
Similar species
Red swamp crayfish are dark red with raised red bumps on the claws. Rusty crayfish have rusty spots on each side of the back and dark bands near the claw tips. Virile crayfish have yellowish knobs on the claws and no white patch.
Profile
| Season | Active spring through fall; females carry eggs under the tail over winter. |
|---|---|
| Starts | Most active once water is above about 50 F |
| Depth | Shallow edges to 30 feet or more |
| How it spreads or reproduces | Walks between connected waters; moved by people as bait or for food |
| Habitat | Rivers, streams, lakes, reservoirs, canals and ponds with rocks, logs or other cover. |
Why it matters in a lake
Native to the Columbia River basin, including Oregon and northern and western Idaho, but has spread into the upper Snake River region where it may compete with native pilose crayfish. Good food for bass and trout and popular to eat; heavy populations can clear out plant beds.
Where it is found
- Idaho: Common
- Oregon: Common
- Wyoming: Not recorded
Classification
| Kingdom | Animalia |
|---|---|
| Phylum | Arthropoda |
| Class | Malacostraca |
| Order | Decapoda |
| Family | Astacidae |
| Scientific name | Pacifastacus leniusculus |
Scuds (Hyalella)
Scuds (Gammarus)
Aquatic sow bugs
Virile crayfish
Red swamp crayfish
Rusty crayfish
Fairy shrimp
Tadpole shrimp
Clam shrimp
Pilose crayfishNeed a hand?
Found it in your lake?
Send us a photo and we will identify it and tell you what it means for your lake.
Idaho / Wyoming (208) 501-4531Oregon (541) 280-0596