New permanent regulations pertaining to the catch, possession and use as bait of crayfish became effective October 2009. The regulations apply to Middle Potomac River, Upper Potomac River and Susquehanna River Basins. In these basins, anglers may not catch, use or possess any species of crayfish unless the head is removed immediately upon capture. Also, anglers may not catch and possess any female crayfish bearing eggs. Eggs on the female are found attached to the underside of the abdomen. These must be immediately returned to the water where they were caught.
The regulations were adopted to prevent the spread of the damaging rusty crayfish. Since the identification of crayfish is difficult even for trained individuals, the ban on the use of crayfish in these watersheds applies to all species.
Rusty crayfish is native to portions of the Ohio River in Illinois, Kentucky, Ohio, and Tennessee. As popular bait for game fishes, this species has been widely introduced outside of its native range. Bait bucket introductions of rusty crayfish have been documented in at least 14 other states and portions of Canada. All of these introductions have had devastating effects on the invaded ecosystems. Rusty crayfish can eliminate native crayfishes and can reduce the quality and quantity of habitat available to other stream species. Rusty crayfish feed heavily on mayflies, stoneflies, and other invertebrates that are important food sources to stream fishes. This species also consumes fish eggs and can destroy aquatic vegetation beds. These habits can impact game fish populations.
In 2006, MDNR banned the rusty crayfish, along with other known invasives, from the state of Maryland. In 2007, the rusty crayfish was discovered in the upper Monocacy River and in the Susquehanna River above Conowingo Dam. Further surveys of these areas determined that the outbreak was contained in these two areas. It is believed to have been unintentionally introduced by anglers as discarded bait dumped into Pennsylvania tributaries to these rivers, and has since spread south across the state line. In 2008, a few specimens were found in Antietam Creek in the Upper Potomac River Basin, so it was included in restrictions as well.
This invasive species has the potential to cause profound changes to Marylandís streams and rivers. MDNR biologists are concerned that the spread of this species may be hastened by additional bait bucket introductions in Maryland. This regulation aims to prevent the inadvertent or intentional movement of this species into other Maryland watersheds.