Ballast water is one of several vectors. Ships use ballast to help maintain stability when there is no cargo on board. Phil briefly outlined several options for treating ballast and some of the hurdles to overcome before they can be implemented at a full-scale level. There was much discussion of possible means to clean out the sediment and water in empty ballast tanks and potential approaches to flushing, heating or cooling ballast water. John Janssen gave a short presentation on round gobies and their effects in the Great Lakes.
Round gobies are prolific and aggressive.
As their population expands they comprise an increasing portion of the diet of sport fish. Round gobies consume zebra mussels depending in part on the size of the mussel and whether they can pull it off the substrate. Zebra mussels and round gobies accumulate contaminants therefore contaminant accumulation up the food chain may be a concern. There was some discussion about the effect of gobies and what preys upon them in their native habitat. Issues Discussion Discussion focused on the effects of invasive species, what can be done to prevent their spread and to stop continued introduction.