Live crayfishes are sometimes used as bait by recreational anglers, and sometimes, live individuals remaining after a long day of fishing are released directly into the water. These ‘bait-bucket’ introductions are thought to be one of the most common mechanisms by which invasive crayfishes are introduced (Ludwig and Leitch, 1996).
Although not typically thought of as pets, crayfishes (and other freshwater crustaceans) have become increasingly popular amongst the pet trade in recent years (Chucholl, 2013), perhaps due to their sometimes striking or unusual color patterns. The popularity of stocking crayfishes in personal aquaria, and the surge of interest among animal breeding hobbyists, have permitted the transportation of live crayfishes across state/provincial borders, and even internationally. However, some crayfishes can grow to a large size quite rapidly, and subsequently, overcrowding or aggression towards other aquatic organisms can become a problem. For this reason, crayfishes housed in aquaria are often released into nearby waterbodies. The effects of the pet trade are evident more so in Europe than in North America at present, where introduced species have transmitted the deadly crayfish plague to numerous native species (Patoka et al., 2014)
Crayfishes are grown and sold commercially for a variety of reasons, primarily for food or for use as bait for recreational fishing. Aquaculture facilities supplying crayfishes to food or bait/tackle vendors are a potential introduction source for commonly cultured, and potentially invasive, species such as the red swamp crayfish (Procambarus clarkii). Facilities culturing non-native crayfishes risk accidentally introducing these alien species by allowing for short-range migrations from culture ponds to nearby natural water bodies either by overland migrations or during flood events. Even facilities culturing other organisms in ponds, such as fish, risk transporting invasive crayfishes over long distances if crayfishes make their way into the ponds and then accidentally into shipments of live animals.