Photo credit: © Matthew Ignoffo, https://flic.kr/p/ctCZZw
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Species at a Glance
While native to the United States in the Missouri, Mississippi, Ohio, and Great Lakes drainages, the virile crayfish, also called the Northern crayfish, has become introduced to new locations throughout the United States through the live pet and bait trades. In these areas it has competed with and displaced native fish and crayfish and reduced populations of snails, macroinvertebrates, and aquatic plants.
Adult virile crayfish reach about 13 cm (5 in) long, with males typically growing larger than females. The body is reddish-brown, olive-brown, or green without any prominent markings. The pincers are green or blue-green with orange tips and are conspicuously studded with whitish or yellow nodules in adults. Paired dark blotches run lengthwise along the abdomen. The rostrum has conspicuous notches or spines near its tip.
The virile crayfish is most often confused with the calico crayfish (Orconectes immunis) and spinycheek crayfish (Orconectes limosus). The calico crayfish differs in having pincers that are gray, purple, or pink, a pale lengthwise stripe along the middle of the abdomen, and a rostrum without lateral notches or spines. The spinycheek crayfish is smaller with distinctive spiny cheeks and legs with orange tips.
This species inhabits rivers, streams, lakes, marshes, and ponds that are permanent and well oxygenated. It prefers warm waters of moderate turbidity with cobble or rocky substrates and abundant logs, rocks, vegetation, and other debris to use as cover. It is also known to dig burrows in river banks and under rocks when water levels are low. It doesn’t tolerate poor water quality or high salinity waters.
Because it is commonly used as bait, and sold in bait shops and aquarium stores, many introductions of virile crayfish have probably occurred through intentional, or unintentional, release from these pathways.
Native to the Missouri, Mississippi, Ohio, and Great Lakes drainages of the United States, the virile crayfish has been introduced to several states outside of its native range, including Maryland, North Carolina, Pennsylvania, West Virginia, and Virginia in the Mid-Atlantic.
Note: Distribution data for this species may have changed since the publication of the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016), the source of information for this description.
The virile crayfish can alter aquatic habitats by decreasing the abundance and diversity of aquatic plants and competing with native species for food and habitat. It has been known to negatively impact species of native crayfish, fish, frogs, snails, insects, and macroinvertebrates. Its burrowing behavior also impacts water quality and clarity by increasing turbidity, as well as impacting irrigation networks and levees.
Information for this species profile comes from the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016).