There are a lot of big questions out there regarding invasive species (IS). IS cause all kinds of economic damage and are a big cause of native species being threatened. Yet this is a very artificial classification structure for biota. Invasive species aren't defined by their evolutionary history or morphology, but rather by the impact they have on human-centric ecosystem services. I think that has caused a lot of confusion in the way we research the subject. However, I'm just rambling a bit here, the focus of this paper is a lot more pragmatic. Essentially this paper looks at how aquatic IS are being spread by boats. And man, it looks like they could be spread really easily.
Essentially, we know that boats moved around by recreational boaters are causing IS to be moved around. As a result, there are all kinds of efforts out there to prevent that from happening. For the most part, those efforts center on 2 approaches: 1) Educate the public and 2) boat inspections. 95% (maybe more) of the effort goes into the first of these categories.
And this is where it all goes wrong.
There probably isn't anywhere in the country that has been more inundated by the 'prevent the spread' of invasive species message than the Great Lakes Region. Since the 1930s, the Great Lakes have been subject to an increasingly devastating series of invasions by non-indigenous species. This has devastated economic and environmental interests throughout the region. So the residents of Wisconsin and Michigan (particularly those who are targeted by these educational efforts) should be more aware of the problems and what they can do to help than anyone else.
And yet they don't seem to be all that aware or all that interested in doing much.
"68% of transient boaters did not always was or dry their boat when moving it overland between waterways...27% did not always remove aquatic weeds they saw attached to their boat and trailer." p 125 (Rothlisberger et al. 2010)I'm reminded of a talk I saw at NABS '08 by the state malacologist of Missouri. Missouri did a similar survey with a bunch of boaters, and got similarly miserable responses (most people had never heard of IS or zebra mussels in particular, and didn't realize they could do anything to help prevent their spread). These respondents were then asked what the state should do. The responses were things like put ads on TV, put ads in magazines, put up signs at boat ramps, etc. After going over these responses, the malacologist sighed heavily and brought up the next slide: That's what Missouri had just spent millions of dollars doing over the previous X number of years. Sometimes you just can't win.
There's more in this paper. For instance, the authors also tested the effectiveness of the boat inspection and wash stations. For some of the smaller organisms (crustaceans and seeds), visual inspection just wasn't very effective. Even a high-pressure wash was only about 90% effective at removing these organisms, and according to the methods, even a ten-minute delay was enough for boaters to become unwilling to participate in a high-pressure wash.
The authors also quantified the amount and type of material being moved around by these recreational boats. On average, they found 37 species per boat, indicating a large potential for this vector to be spreading invasive species.
Despite massive educational efforts over the past 20 years, a majority of boaters don't seem to be taking the basic steps necessary to prevent the spread of aquatic invasive species. Additionally, it now seems clear that these boats do possess the ability to transport a significant variety of aquatic organisms (although it isn't clear how long these species would remain viable out of the water).
Rothlisberger, J.D., Chadderton, W.L., McNulty, J., & Lodge, D.M. (2010). Aquatic invasive species transport via trailered boats: What is being moved, who is moving it, and what can be done American Fisheries Society, 35 (3), 121-132