Research ProjectBaitworm Trade

The Baitworm Trade as a Vector for Invasions in Estuarine and Coastal Systems

  • Shipment of baitworms from Maine

    A shipment of bait (bloodworms) packed in algae (wormweed). Photo by Monaca Noble

  • Amphipoda from wormweed

    A collection of live amphapods, isopods, and snails found in the algae used to transport bait worms. Photo by Monaca Noble

  • Bloodworm and algae. Photo by Monaca Noble

    A bloodworm its packing algae. Photo by Monaca Noble

Affiliated Labs

Project Goal

We are looking at the likelihood of invasion of organisms associated with the live baitworm trade from its source in Maine to its distribution in the United States. We are working with the industry to develop effective packing material treatments to reduce hitchhikers and exploring options to reduce bait-related introductions.


Amy Fowler and Anne Phillips sorting wormweed
Dr. Amy Fowler and Anne Phillip carefully comb through all the wormweed clearing hitchhiking organisms. Photo by Monaca Noble

While major introduction vectors*, like commercial shipping, transport extraordinary volumes of many marine species around the globe, less conspicuous vectors, like the live saltwater trade (e.g., bait, seafood, pets), are also significant movers of species, resulting in major introductions such as the European Green Crab, one of the most notorious invaders worldwide. Though the overall volume of organisms transported is comparatively lower in live trade, these vectors may be more efficient means of introducing new species because they are less environmentally stressful for the organisms in transport, and often introduce reproductively active adults.

Our lab has been closely investigating the live saltwater baitworm industry in North America. Polychaete baitworms and marine algae ("wormweed") are harvested from coastal mudflats and sold to bait dealers in Maine, where they are shipped via overnight mail to locations around the USA and abroad to Europe and Asia. Wormweed is used as packing material to keep worms protected during transport and often serves as habitat for numerous marine species. After bait is sold, the packing algae and baitworms may be discarded in coastal environments, providing opportunities for invasion. To track this vector, we have focused on biological characterization (taxonomic, functional, and genetic diversities) from field to bait shop, using the mid-Atlantic as a model recipient region. We have discovered over 100 associated taxa* in packing algae, and though this diversity drops significantly in recipient bait shops, a considerable number of live organisms still survive the journey. As such, we have been exploring ways to treat the algae to eliminate the majority of live diversity in bait-boxes. We found that a simple tap-water soak was an effective osmotic shock that killed most associated organisms, representing a cost-effective way to reduce invasion risk. Finally, with our colleagues at Maryland SeaGrant and UMD, we have been exploring social science and management implications related to this live trade vector. 


Sá, Erica, Fidalgo, e. Costa, Cancela, da Fonseca, Alves, Ana Sofia, Castro, Nuno, dos, Santos Cabral, Chainho, Paula, Canning-Clode, João, Melo, Pedro, Pombo, Ana Margarida and Costa, José Lino. 2017. Trade of live bait in Portugal and risks of introduction of non-indigenous species associated to importation. Ocean & Coastal Management, 146 , 121-128.

Blakeslee, April M.H.,  Amy E. Fowler, Jessica L. Couture, Edwin D. Grosholz, Gregory M. Ruiz, and A. Whitman Miller. 2016. Vector management reduces marine organisms transferred with live saltwater bait. Management of Biological Invasions. Volume 7, Issue 4: 389–398. 

Fowler, Amy E., Blakeslee, April M. H., Canning-Clode, Joao, Repetto, Michele F., Phillip, Anne M., Carlton, James T., Moser, Fredrika C., Ruiz, Gregory M. and Miller, A. Whitman. 2016. Opening Pandora's bait box: a potent vector for biological invasions of live marine species. Diversity and Distributions, 22(1): 30-42. doi:10.1111/ddi.12376

Miller, A. Whitman, Chang, Andrew L., Cosentino-Manning, N. and Ruiz, Gregory M. 2004. New record and eradication of the northern Atlantic alga Ascophyllum nodosum (Phaeophyceae) from San Francisco Bay, California, USA. Journal of Phycology, 40: 1028-1031.


Dr. Whitman Miller
Term Definition
Vector A means of introduction or transfer between locations
Taxon (plural Taxa) A taxonomic category or group, such as a phylum, order, family, genus, or species.