Invasive Species: Concerned About Rock Snot

I am in Providence, Rhode Island, attending the "International Didymo Conference," where scientists and policy experts from around the world have gathered to talk about this aquatic invasive species. If you're not familiar with the diatom Didymosphenia geminata, you should be. "Rock snot," as it is often called, has the ability to spread quickly. For example, since the first blooms of this alga were detected in one river on New Zealand's South Island in 2004, it has infiltrated many other major river systems there (fortunately it has not spread to the North Island). And it's a growing concern here in the United States as well.

In a nutshell, this gunky, globby goo stifles rivers, essentially suffocating invertebrates (what trout eat), and the effects on the fish themselves are still unclear. Flushing flows in rivers below dams can alleviate the problem, but didymo tends to grow back quickly. Of all the potential invasive threats to our already fragile trout streams and rivers, this one ranks high on the list. It's part of the reason why some states have enacted felt sole bans on wading boots.

But I have to wonder if banning felt can really have a significant, lasting impact. I sometimes think that those of us who have sworn off felt (or have been made to do so) consider that a cure-all, when in fact the bottoms of our boots are only part of the issue. Organisms can survive (and be transported) in many fabrics.

Be honest with me. How thoroughly do you really wash or freeze your wading boots, if you do so at all? I would estimate that 75 percent of anglers think they are doing the right thing. Based on what I am learning here, however, I'd say that less than 25 percent are actually doing a thorough job of cleaning or freezing boots in a way that can really reduce the threat spreading invasive species. Sadly, I think I'm probably one of those anglers stuck in the middle somewhere.

We clearly need more information. Not the detailed science, rather the basics on "what it is, why it matters, and what we can do about it." The Invasive Species Action Network is a good place to find the straight scoop on didymo and other invasive threats, and I strongly encourage you to check out that website before you lace up and start fishing this spring.