From the Carroll County Times
By Carrie Ann Knauer, Times Staff Writer
http://www.carrollcountytimes.com/articles/2009/10/13/news/local_news/newsstory1_crayfish.txt
Tuesday, October 13, 2009
DETOUR — Researchers are testing Maryland streams and rivers this month to see if an invasive crayfish that is a competitive threat to native crayfish has spread.
The Maryland Department of Natural Resources is in the middle of its third annual crayfish sampling in the Potomac River watershed, which includes the northwest section of Carroll. The rusty crayfish has been found for two years in a row in Piney Creek, said Jay Kilian, a natural resources biologist with the DNR, and researchers plan to go back to see just how far upstream it has migrated.
The rusty crayfish is native to the Ohio River watershed, Kilian said, and is slightly larger and more aggressive than other native species of crayfish found in Central Maryland. The rusty crayfish was found in Southern Pennsylvania more than a decade ago, Kilian said, and scientists believe it was introduced there accidentally by fishermen emptying their bait buckets with live specimens at the end of a day.
Kilian said the DNR sent surveys to 10,000 Maryland fishermen at the end of 2008 and found that the majority use live bait and dump their bait at the end of a fishing day. Kilian said fishermen may believe this is the most humane thing to do, but it causes bigger problems for the environment.
“We have a lot of anglers really doing the wrong thing, without realizing it,” Kilian said.
The DNR is trying to publicize the message that it would be safer if fishermen dumped their bait at home or froze it for use next time, Kilian said.
To prevent the further spread of invasive crayfish, DNR put out a temporary emergency ban last summer on catching or possessing any species of crayfish in the watersheds where rusty crayfish had been found to prevent the possible spreading of the species to any other Maryland bodies.
But the department realized that some people like to catch the crayfish for food, and that the regulation was preventing them from being able to do that, said Sarah Widman, a regulatory administrator with the DNR.
The DNR has altered the regulation to allow people to catch and possess crayfish in these watersheds if the head is removed behind the eyes — thus ensuring the invertebrate is dead. The ban is now in effect in the Middle and Upper Potomac River basin and Susquehanna River basin.
Once the rusty crayfish is established in a new water body, there’s little that can be done, Kilian said. The best thing you can hope to do is prevent the spread through educating the public about not dumping bait or moving animals, and study them until they are better understood, he said.
“The hope is eventually we’ll be able to learn whether it’s possible to stop them,” Kilian said.
Three different professors at Hood College in Frederick and one at Mount St. Mary’s University in Emmitsburg, along with some students, are working on research projects revolving around rusty crayfish.
Sue Carney, an associate professor in biology at Hood, said she has been looking at the genetic code of rusty crayfish caught in the Monocacy watershed. She is hoping that the study will help them learn whether the crayfish in Central Maryland are from a few or many introductions, whether there is a particular strain that is surviving better than others, and what makes the rusty crayfish such a good competitor.
Eric Annis, another assistant professor of biology at Hood, said he is trying to study the impact the rusty crayfish are having on their new environment.
“One of the things they’re known for is actually clear-cutting the bottom vegetation,” Annis said.
That’s of particular concern because of fear of the crayfish making their way into the Chesapeake Bay, Annis said.
The results of the DNR’s October stream surveying will help the researchers learn how the species is spreading. Annis said that from what he saw this summer, he believes they may be moving a mile each year.
“We don’t really know what’s going to happen in the Monocacy or other streams,” Annis said.
Reach staff writer Carrie Ann Knauer at 410-857-7874 or carrie.knauer@carrollcountytimes.com.
