Wallace, J.R., 2003. Bait Shop Introductions of Aquatic Invaders: Revelations from a Crayfish Survey, Millersville University.

Proceedings of the Aquatic Invaders of the Delaware Estuary Symposium, Malvern, Pennsylvania, May 20, 2003, pp. 11-12.

Bait Shop Introductions of Aquatic Invaders: Revelations from a Crayfish Survey

Abstract: Many ecologists have noted that besides alterations to land use, the introduction of nonindigenous species (NIS) is probably one of the greatest threats to freshwater biodiversity in the 21st century. In North America, several vectors or methods of introduction are of increasing importance, such as aquaculture, aquarium/pond trade, live food trade as well as the biological supply trade. Of special concern in Pennsylvania and many other states is the problem of the live bait trade. Dr. Wallace discussed how a county crayfish survey revealed such a problem and how bait shops and state regulations can be improved to eliminate the threat on native aquatic faunal diversity.

The distribution of live bait is a potential vector for new introductions in Pennsylvania. Although data is available through unpublished studies, it is difficult to gather bait shop data from interviews and surveys. Dr. Wallace presented two case studies on the rusty crayfish (Orconectes rusticus) and the nuclear worm (Namalcystis aluna).

Rusty Crayfish
Lodge et al. examined vectors for rusty crayfish introductions (Fisheries 25: 7-20). In Pennsylvania, there are three primary vectors: legal stocking in natural waters, aquarium supply trade, and live bait introductions. Of these vectors, only the first is regulated in Pennsylvania. However, a permit is also required to sell approved species in bait vending machines found at gas stations, boat launches, and recreational fishing areas.

The rusty crayfish competes with native crayfish species. In a survey of Midwestern lakes, ecological impacts of rusty crayfish included disease, competition, fish predation interactions, reproductive interference, and hybridization with native species. They have also been known to reduce macrophyte and algal cover and reduce macroinvertebrate abundance (especially snails).

Nuclear Worm
The nuclear worm was introduced to the West Coast from Vietnam. In the Chesapeake and Delaware Bays, anglers use nuclear worms as bait for stripers and white perch. The worm is an excellent bait because it requires no refrigeration and the cost is relatively low. At $6-7 apiece, one worm can be diced into multiple pieces. In general, the import of live worms for bait is a profitable business. Between 1998-2000, imports were valued at $70 million/yr. Live worms are widely sold over the Internet and potential impacts arising from their import and distribution include:

• The risk of introducing other species attached in the seaweed packaging
• Transfer of disease-causing bacteria
• Ecological or genetic displacement of native species.

View Entire Proceedings (9.75 MB)
Contact: John Wallace, Department of Biological Sciences, Millersville University, P.O. Box 1002, Millersville, PA 17551-0302, USA
Key Words: Nonindigenous, Rusty_crayfish, Prevention
Product Type: Publication, Proceedings
User Type: Resource_Management