Cohen, Andrew 2012. Aquatic invasive species vector risk assessments: live saltwater bait and the introduction of non-native species into California. [Report] Center for Research on Aquatic Bioinvasions (CRAB) Richmond, CA for California Ocean Science Trust. 59 pp.
Summary: Most of the live saltwater bait sold in California is harvested and sold locally, and thus poses little risk of introducing non-native species to new regions. • However, there are four species of polychaete worms that are or have recently been imported from other coasts and sold live in California, and two thalassinid crustaceans (ghost shrimp and mud shrimp) that are imported from Washington or Oregon. These are the species of greatest concern. • Probably the greatest demonstrated risk lies with the Atlantic seaweed that is used to pack two baitworm species imported from Maine. This seaweed packing carries a wide selection of intertidal organisms from the New England coast, including two species that invaded New England from Europe and had large, negative impacts on native species distributions, habitats and fisheries in New England. Some non-native species have become established in California as a result of this mechanism, many other organisms are transported by or available for transport by this mechanism, and further introductions are to be expected. Although an assessment of management options is outside the scope of this study, it is clear that several feasible options are available to reduce or eliminate this risk, including requiring distributors or retailers to remove and dispose of the packing seaweed before sale to customers, banning the use of seaweed as packing for imported worms, or banning the import and sale of these worms. • Bopyrid parasites carried by thalassinid bait species have the potential to harm native thalassinids. Although it’s not clear that bait shipments can be effective in introducing one of these parasites (Orthione griffenis), impacts by this parasite can be devastating, and further assessment of the risks from bopyrid parasites in the bait trade are fully warranted. • Whatever the risks of the current mix of imported bait in California, bait species from other parts of the world, including from an Asian industry active in producing and promoting a variety of baitworm species for live export, are likely to be sold in California and to present new risks, unless management actions are taken to limit or prevent this. • Existing California law requiring a permit from CDFG in order to import live bait provides a mechanism for monitoring and managing current and potential future imports of live saltwater bait species, if the state chooses to implement that law.