Aquaculture as a vector for marine invasions in California
Although ballast water and hull fouling are widely recognized as important vectors for marine invasions, the risk posed by commercial aquaculture remains poorly quantified. To understand the importance of aquaculture as an invasion vector in California, we conducted an analysis of both current and historical introductions of marine and estuarine species associated with aquaculture using a comprehensive database (‘NEMESIS’) and permitting records for species imported into California. Our results showed that 126 non-native species associated with commercial aquaculture have been reported from California waters and 106 of these have become established. The vast majority are unintentional introductions linked to historical importation practices of the aquaculture industry. To understand the consequences of these invasions, we reviewed the literature on the impacts of mollusk and algal species introduced into California via aquaculture. Of the few studies we found, the majority demonstrated negative impacts on native species. Finally and significantly, we found that changes in aquaculture importation practices over the past decade have resulted in most shellfish currently being imported as larvae or juveniles. Consequently, rates of unintentional introductions have been reduced. We cautiously conclude that current aquaculture importation in California represents a minor risk as a vector for introductions of NIS.
KeywordsInvasive Marine Aquaculture Vector Impacts California
We wish to thank the Smithsonian Environmental Research Center’s Marine Invasions Research Laboratory and in particular G. Ruiz, B. Steves and P. Fofonoff, for facilitating access to the NEMESIS California database. We would also like to thank the many state and federal agency officials who volunteered their time and effort for our work including K. Holzer, J. Moore and K. Ramey. We also thank the Executive Director (S. McAfee) and staff of the Ocean Science Trust (R. Gentry, E. Kramer-Wilt) for facilitating the project and coordinating project investigators. This work was supported by the California Ocean Protection Council through Proposition 84 funds as well as additional support from the California Ocean Science Trust.
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