Skip to main content

What's Up Magazine

Invasive Animals Continue to Thrive in MD

Feb 24, 2011 09:42PM ● By Anonymous
Northern snakeheads and nutria, some of the state’s more well-known invasive animals, are continuing to push out many of Maryland’s native species and doing harm to ecosystems. These invasive species were allowed into this country under a law governing animal imports, which was passed in 1900, and has not been changed since that time.

According to the National Environmental Coalition on Invasive Species (NECIS), updating this federal legislation, the Lacey Act, will prevent the future introduction of potentially harmful non-native wildlife species and the diseases they carry.

“In this globalized world, animals are traded across continents every day, and the rules governing the live animal trade in this country need to be brought into the 21st Century,” said Dr. Phyllis Windle, NECIS spokesperson. “Adding a pre-import screening process will prevent the arrival of animals that can potentially harm the ecosystem and economy, endanger native species, or compromise the health of people and animals in this country.”

Nutria, large aquatic rodents native to South America and initially imported to Louisiana, became established in Maryland when a few animals escaped from a fur farm in the 1940s. Nutria are voracious consumers of the vegetation of tidal marshlands, leaving mudflats in their place. Over the past six years, wildlife managers have removed more than 13,000 nutria from the wetlands of the Chesapeake's Eastern Shore.

Northern snakeheads, imported for the Asian food market, were first discovered in 2002 in a Crofton, MD, pond where they were released by someone who no longer wanted them.Although the snakeheads were eradicated from the pond, they began appearing in the Potomac River in 2004, apparently as the result of a subsequent release. The species is now well established in the Potomac River and several of its tributaries in Maryland and Virginia, and is competing with other species for food and habitat.

"Despite this country’s bad experiences with invasive animal species, the annual volume of live animal imports into the United States has roughly doubled since 1991,” said Peter Jenkins of Biopolicy Consulting, based in Bethesda, MD, and principal author of Broken Screens: The Regulation of Live Animal Imports in the United States. “The ongoing non-native animal invasions and disease outbreaks they cause could be prevented if the initial entry of risky species was blocked at or before our borders.”

The Lacey Act gives the U.S. Fish and Wildlife Service (FWS) limited power to declare species injurious and to prohibit their import to the United States. During the 111 years since the Lacey Act was adopted, only about 40 animal groups have been prohibited under this legislation, and usually long after the animals have been imported, escaped into the wild, and are causing harm. By modernizing the Lacey Act, the U.S. Congress can empower the FWS to first assess the potential risks associated with a species proposed for import before deciding whether to allow or prohibit its trade into the United States.

“Under the current law, it takes an average of four years for the federal government to stop the importation of potentially harmful wildlife,” said Kristina Serbesoff-King who directs The Nature Conservancy’s Florida Invasive Species Program.  “This action often occurs after a damaging, non-native species has already become established and when eradication can be expensive and nearly impossible.”

As a leading import market, the United States receives hundreds of millions of non-native animals each year. Often, they escape from captivity, are dumped by those who no longer want them, or are released into ecosystems by floods and storms. These non-native animals can spread widely, crowd out native wildlife, fundamentally alter natural systems, and spread infectious pathogens and harmful parasites.

Following are examples of invasive animal species that have become established in other areas of the United States:

  • Burmese pythons, descendants of pets imported from Southeast Asia that were illegally released in the wild, are reproducing and thriving in the Everglades and other south Florida wetlands.Estimated at 30,000 in number, the snakes are considered both a threat to the restoration of the Everglades and to human safety, with the state working to control and eradicate the population.
  • Asian carp, once confined to southeastern aquaculture ponds, are now thriving in the Mississippi River basin, with an only an electric barrier to keep these giant fish out of the Great Lakes, where their damaging spread is likely to be unstoppable. The federal government spent in 2010 alone $79 million trying to prevent their invasion of the Great Lakes.
  • Indian mongooses brought to Hawaii and Puerto Rico to control rats and snakes in sugar cane fields, became a menace, damaging banana and papaya crops and carrying infectious diseases, and are to blame for the listing of many birds, turtles, lizards and rabbits on the endangered species list worldwide. Responsible for approximately $50 million annually in damages in Hawaii and Puerto Rico alone, mongooses also are carriers of leptospirosis and rabies.
  • Red lionfish from the Indo-Pacific,introduced to the Atlantic Ocean as aquarium escapees, have formed large populations from Florida to as far north as New Yorkand have now invaded the Gulf of Mexico along the coasts of Florida and Louisiana down to Mexico. These venomous fish areaggressive predators of shrimp and other native commercial species such as snapper and grouper.
  • Gambian giant pouched rats, pet trade imports from Africa, carried the highly contagious and potentially fatal monkeypox virus to the United States in 2003, resulting in an outbreak that sickened 71 people in six states.