Live Bait Packaging: A Threat to the Health of the Chesapeake Bay?

Live bait packages shipped to the Mid-Atlantic from distributors in Maine harbor dozens of species of non-native, marine organisms, a newly published study says. These species can end up in our region’s waters, where they may become invasive and alter ecosystems.  

The finding came from a research project led by Maryland Sea Grant that studied the Maine live bloodworm trade and how to limit the potential spread of invasive species into the Mid-Atlantic from this bait source. 

Maine has an active industry that ships live bloodworms throughout the world. The worms (Glycera dibranchiate) are packed in seaweed (a brown algae called Ascophyllum nodosum) to keep them healthy during transport. The seaweed, also called wormweed, is harvested in Maine’s coastal waters, and species like crabs and snails can live in it. But it can also harbor invasive organisms that could pose a threat to waters in the Mid-Atlantic.

The containers of worms and wormweed are part of a vector – a transportation system that allows invasive species to move to a new location where they are not wanted. This particular vector starts with the wild harvest of bloodworms and wormweed harvest from Maine’s tidal waters. The creatures and the algae go through several stages of re-packaging and shipping before arriving at bait shops across the globe for purchase by anglers. The risk to Mid-Atlantic waters can arise when fishermen buy and use bait and then improperly dispose of the bait by throwing its wormweed packaging into the Chesapeake Bay and other local waterways. And all of the non-native organisms living in the wormweed get thrown in with it.

Previous studies had identified a total of 56 non-native species living in live bait packaging shipped from Maine. The new study uncovered an additional 58 of these “hitchhiker” species, based on identification of a whopping 17,798 live organisms by the research team. Two of the 114 total identified species are harmful algae. One of these, Alexandrium fundyense, releases a toxin that paralyzes shellfish. Another, P. multiseries, creates toxic blooms that release domoic acid, which is toxic to shellfish. That’s a concern for Maryland, where the shellfish industry is important and growing.

An article describing these findings was published in the journal Diversity and Distributions by Amy Fowler of the Smithsonian Environmental Research Center and colleagues. 

The scientists who carried out the study counted the individual organisms and species in wormweed packaging shipped directly from Maine distributors as well as worms and wormweed that Mid-Atlantic distributors and retail stores obtained from these distributors, repackaged, and sold.

The study found that the wormweed in Maine waters and Maine distributors’ packages contained significantly more organisms and a larger range of species than the local Mid-Atlantic packages did. Some organisms attached to the wormweed died during the journey, but enough survived to pose a threat to the Bay and other Mid-Atlantic waterways.

Keeping Invasives Out

Fowler and her colleagues describe reasons that make the live-bait vector very effective at introducing non-native and potentially harmful species into a variety of locations. In California, for example, multiple arrivals of invasive species are attributed to the Maine live bait vector, and many of these organisms have been shown to cause environmental harm.

One reason that this vector can be so harmful is that many of the hitchhikers in the wormweed are juvenile or adult organisms, which are susceptible to parasites. In contrast, many other invasive-species vectors – such as the ballast water dumped in U.S. harbors by foreign cargo ships – are less likely to transport parasites because these vectors contain primarily larval stage organisms. Most types of parasites target adult organisms and do not infect larvae.  The most common example of parasites present in bait packaging is flatworms, or flukes, which prey on the periwinkle snail, a hitchhiker often found in wormweed. Reducing the amount of susceptible organisms in bait packaging reduces the chance of parasites being present and introduced into waters in the Mid-Atlantic and elsewhere.

Something else sets apart the live bait vector from others. Unlike cargo-ship ballast water, there is a lack of regulations specifically designed to prevent non-native species from being transported through marine bait packaging material.

The good news is it wouldn’t be very hard to more effectively manage the shipment of live bait and minimize the amount of species being transported.  Fowler’s article lists measures that can be taken at multiple levels of the live-bait industry – distribution, retail, and consumer.  

Live bait distributors can switch their packaging to blank newspaper soaked in salt water instead of wormweed, as some Maine live bait distributors have already begun doing. Distributors could also intermittently soak the wormweed in water of varying salinities. This causes something called osmotic shock, and kills most of the organisms living in the wormweed, but not the weed itself.

Mid-Atlantic retailers who sell live bait prepared by Maine distributors could also simply remove the wormweed packaging before selling the bait to customers. Fishermen who use live bait can protect their fishing waters by doing the simple task of throwing wormweed in the trash instead of throwing it in the bay. If retailers and anglers dispose of the wormweed properly, hitchhiking organisms will never reach the Mid-Atlantic waters.

Chances of invasion increase with the number of organisms released into a foreign ecosystem. So far, scientists do not believe species introduced by wormweed have become harmfully invasive in the Mid-Atlantic region. These preventative steps could stop that from ever happening.

Photo, top: The European green crab (Carcinus maenas) is among the hitchhiker species found in wormweed packaging. Credit: Smithsonian Environmental Research Center

For more information

Maryland Sea Grant’s website describes the project of which this study was a part. A public education campaign, “Trash Unused Worms & Packaging,” educated Mid-Atlantic live bait dealers and anglers to properly dispose of the wormweed packaging. http://www.mdsg.umd.edu/topics/aquatic-invasive-species/bait-worm-study