More than 5,000 alien species have become established in North America since the founding of the English Colony at Jamestown. Of these, the Maryland Invasive Species Council has identified about 100 that present a serious threat in our region.

Which one is the worst? That depends.

If you care about Bay grasses, the mute swan might be your species of greatest concern.

For a crabber, it might be the mitten crab. And if you are a herring, the blue catfish is a terrifying new predator lying in wait.

The Chesapeake Bay Program identified six species that present immediate biological threats in Bay ecosystems:

Maryland has ongoing programs to address each of them, and in many cases, their numbers have been dramatically reduced.

Giant reed is present in the greatest numbers. Its populations cover thousands of acres and occur in every Maryland coastal community. They are still expanding, but the plant has been removed from many natural habitat areas.

The zebra mussel has been kept out of Maryland waters by sharp-eyed boaters and fishermen who have cleaned the hitch-hikers from their gear. These species have the capacity to quickly expand their populations and can rapidly become a major problem, so it is critical that control measures are applied constantly.

- Jonathan McKnight
Associate Director, Wildlife & Heritage Service
Maryland Department of Natural Resources

 For more information:
Maryland Invasive Species Resource Center

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