Jay Kilian, Maryland Department of Natural Resources, Resource Assessment
Attention anglers! What lies in your bait bucket has the potential to damage Maryland’s waters and the quality of your most prized fishing hole. Your favorite type of bait may help you catch a big fish, but it may also be an invasive species. Rusty crayfish, fathead minnow, goldfish, red swamp crawfish, banded darter, virile crayfish, red wigglers, rainbow darter, and nitro-worms, to name just a few of the non-native bait species that have been used in Maryland waters, are now established in the state. Some of these introductions have caused little harm, while others have caused considerable ecological damage. Many other bait species and bait-related diseases are threatening to join the list of Maryland invaders. With the 2021 fishing season underway, your actions can make the difference and help prevent further introductions of invasive bait species. For this reason, the Maryland Invasive Species Council has chosen live bait as the July 2021 Invader of the Month.
Dumping unused bait into a stream, river, lake, or on shore is often viewed by anglers as humane or even beneficial to game fishes. However, this simple act can have unexpected repercussions. The release of live bait by anglers has been responsible for the introduction of invasive crayfishes, fishes, earthworms, and fish diseases across the nation. Following their introduction, invasive bait species can quickly overpopulate invaded areas and reduce native biodiversity, water and habitat quality, and cause dramatic changes in ecosystem function. These changes can cascade through an aquatic food web, affecting everything from algae to commercially and recreationally important fishes. Even a benign-looking earthworm can have ecological impacts. Dramatic changes to forests of northern North America have been linked to invasive earthworms such as Lumbricus terrestris, a European species commonly sold as bait. These invasive earthworms alter soil chemistry, reduce the diversity of other invertebrates, amphibians, and native vegetation, and hasten the spread of invasive plants. At least nine non-native earthworms have been introduced in Maryland – many of these are common bait species. Some of these have impacted Maryland ecosystems (see Invader of the Month https://mdinvasives.org/iotm/april-2015/).
The earthworms, crayfishes, and fishes used as bait are not the only concern. Even the packing material within a bait container can harbor small invaders. For example, live bloodworms are a popular bait among anglers targeting spot, croaker, striped bass and other fishes in the Chesapeake Bay and its tributaries. Bloodworms used by anglers in the bay and Mid-Atlantic region originate from coastal Maine where they are harvested from intertidal mudflats, packed in seaweed known as wormweed, and shipped to bait dealers worldwide. A recent study of the bloodworm trade conducted by scientists at the Smithsonian Environmental Research Center found that a wide variety of small snails, crabs, isopods, amphipods, and other invertebrates live among the wormweed and can survive the transit from Maine to Maryland hidden within a bloodworm bait container. Anglers who chose to dump their unused worms as well as the wormweed from their bait containers into Chesapeake Bay waters may unknowingly introduce another problematic, invasive species.
Photo Credit: Dr. Amy Fowler – George Mason University
Bloodworms, a common bait used in the Chesapeake Bay, are often imported in containers of wormweed (pictured here) from the coast of Maine. This wormweed can contain a wide variety of other non-native, potentially invasive ‘hitchhikers’ that could pose a risk if discarded in Maryland waters.
Parasites, fungi, fish pathogens, and other microscopic organisms associated with live bait can dramatically reduce the health of anglers’ favorite game fishes. For example, Viral Hemorrhagic Septicemia (VHS) is a highly contagious disease that has caused massive fish kills in the Great Lakes since 2005 and has spread to other waters in New York, Ohio, Wisconsin, and Michigan. This disease infects over 40 species of fishes including rainbow trout, brown trout, walleye, yellow perch, channel catfish, northern pike, and black crappie. The use and release of contaminated bait is believed to be one of the important vectors responsible for the spread of this disease. To prevent its spread, natural resource agencies and bait dealers in the Great Lakes region have taken steps to prevent the culture, sale, and export of contaminated bait.
Fortunately for Maryland, these actions should greatly reduce the likelihood that VHS hitchhikes make it into the state on contaminated bait. However, complete protection of our waters from invasive bait species and from fish diseases like VHS requires an informed and vigilant angling community here in Maryland. Your actions can make all the difference.
You can help prevent the spread of invasive bait species by doing the following:
- Never release unused live bait and packing material directly into water or on shore
- Give your unused live bait away to other anglers
- Save your bait for your next fishing trip
- Dispose of your unused live bait humanely by placing it in a freezer
- Never carry organisms from one watershed to another
And most importantly, spread this message to your fellow anglers. Give them this information and tell them to pass it on!
For more information on invasive bait species and Maryland’s bait regulations, visit http://www.dnr.state.md.us/invasives/
Originally posted as the Invader of the Month in April 2011. Updated May 2021.