Transport of Crayfish From
Waters West of the Continental Divide Prohibited |
| Effective January 1, 2011, you either have to return crayfish immediately to the water of origin or kill immediately upon catch, take into possession, and separate the tail from the abdomen. |
Transport of Crayfish From
Sanchez Reservoir State Wildlife Area Prohibited |
| Rusty crayfish have been discovered at Sanchez Reservoir State Wildlife Area in Costilla County. To prevent the spread of rusty crayfish within and beyond Sanchez Reservoir State Wildlife Area, the Director of Parks and Wildlife has issued an immediate order (3MB PDF) that prevents the removal of any live crayfish from Sanchez Reservoir State Wildlife Area. |
The Colorado Parks and Wildlife is monitoring the state’s waters for the introduction of an aggressive invasive species, the rusty crayfish (
Orconectes rusticus).
Original spread was by anglers using the crayfish as bait, but the crayfish were also harvested for regional bait markets and for biological supply companies, activities which probably helped spread the species further.
Rusty crayfish inhabit lakes, ponds, and both pool and fast-water areas of streams, which makes many areas in Colorado potentially suitable habitat. They are considered opportunistic feeders and will eat a variety of aquatic plants, benthic invertebrates (like aquatic worms, snails, leeches, clams, aquatic insects, side-swimmers and waterfleas), detritus (decaying plants and animals including bacteria and fungi), fish eggs, and small fish.
These crayfish reproduce by sexual reproduction, but both a male and a female crayfish are not necessary to begin a new infestation. One female carrying viable sperm could begin a new population if released into a suitable environment.
Rusty crayfish may cause a variety of negative environmental and economic impacts when introduced to new waters:
They are an aggressive species that displace native crayfish through crayfish-to-crayfish competition, forcing other crayfish species from daytime hiding places which renders them vulnerable to predation by fish.
- Their aggressiveness and high metabolic rates allow them to destroy aquatic plants, causing decreased plant abundance and diversity. This causes decreases in habitat for invertebrates, shelter for young fish, forage for some species of fish, fish nesting substrates and increases erosion.
- Juvenile rusty crayfish feed heavily on benthic invertebrates, which causes competition with juvenile fish. Although fish will eat rusty crayfish, their food quality is not as high as many of the invertebrates they replace.
- They may harm fish populations by eating fish eggs, but there are no studies linking fishery declines with egg predation.
- Native crayfish are susceptible to bacteria and viruses which could be introduced by the rusty crayfish.
How to Identify the Rusty Crayfish
This species, which is native to the Ohio River basin, can often be identified by two rust colored marks on its mid-back area, near the area where one would place a thumb and finger to pick the animal up.
Help Stop the Spread of Rusty Crayfish
Environmentally sound ways to eradicate or control introduced populations of rusty crayfish have not been developed. Some chemicals selectively kill crayfish, but none are currently registered for crayfish control or are able to remove rusty crayfish without also killing native crayfish species. Intensive harvest may help reduce adult populations and minimize some impacts. The harvest of rusty crayfish for food may provide the only beneficial use for this exotic.
The best way to prevent further ecological problems is to prevent or slow their spread into new waters.
Report Sightings!
Please report sightings of rusty crayfish to
Elizabeth Brown, Invasive Species Coordinator, 303-291-7362.