Inconvenient Truth

Several days ago I was fortunate enough to find myself fishing along the edges of Montana's Boulder River (Yellowstone River tributary) on a beautiful spring day. It hadn't been that long since I'd gotten my boots wet, but upon entering the river it immediately seemed that my wading skills were in a severe state of regression. I was slipping and sliding on the freestone's stream bed, to the point that I commented on it to my fishing partner. He grunted in return. I didn't think much of it, and chalked it up to rusty legs and a few broken boot studs.

After a couple of dozen drifts with a tandem nymph rig, I was becoming increasingly frustrated by the need to clear my flies of moss after every drift. Again, I commented on it to my fishing partner. He rather casually replied, "it is rock snot... didymo". This had me reeling, I was shocked. I consider myself a fairly knowledgeable angler, and because I work in the industry I tend to keep my ear to the ground. Yet I had no idea that didymo was present in Montana. It weighed heavily on my mind throughout the rest of the day, despite the fact that the fishing was some of the best I'd experienced in quite some time (read a report of the day here).

Treating my wading boots to a soak and scrub.

Upon getting home I did a little research, and sure enough, didymo is present in Montana, not only in the Boulder, but in a number of streams (Stillwater River, East and West Rosebud Creeks, Bitterroot River, Kootenai River and numerous streams in Glacier NP). I contacted Bob Wilshire of the Invasive Species Action Network based in Livingston to find out what is being done about the presence of didymo in Montana.

The answers I received from Bob were informative, and surprising: "Didymo has been in the Boulder since the early 2000's. We don't know exactly when it showed up, but it really has not gotten any worse since then. One factor could be the severe flood events that the Boulder has. Any high water that moves substrate makes it tough for didymo." Bob went on to say that, "MT Fish, Wildlife & Parks considers it to be a native species so they don't monitor it. We are just beginning a year long study but all we will do is make monthly observations to document its yearly growth patterns."

This information really threw me for a loop. What little I had heard about didymo in the past was always very negative... but of course much of that stems from its profusion in New Zealand waters. I'm still doing research and learning more about the species, but it appears that there is only minimal evidence linking it to the reduction of fish populations. Some studies that I have come across suggest that it has the ability to alter the benthic community within a stream. At the very least the species is a nuisance to anglers, making wading difficult and befouling nymphs and streamers.

Upon getting home from the Boulder that day, not only did I research didymo, but I also tossed my wading boots and waders in my bathroom sink for a cleaning (admittedly a rarity). I shuddered at the thought of being responsible for introducing didymo to other waterways.

It wasn't but a couple of days later that I opened my email to find the latest e-newsletter from the Madison River Foundation. The bold heading, "Warning! Milfoil has been identified in the Jefferson River," caught my attention. This was the first I had heard of the presence of this species in SW Montana. Eurasion Watermilfoil is an aggressive, non-native aquatic species that thrives in slow river environs, backwaters, and lakes. It can be very damaging to native aquatic ecosystems and once established it is difficult to control. It is easily transported between water bodies unknowingly by anglers and recreationalists via waders, wading boots, boats, etc.

Montana isn't immune to aquatic invasive and nuisance species, yet it seems that the warnings tend to fall on deaf ears. The public awareness campaign reminding anglers to, "Inspect, Clean, and Dry" wading gear has been widely circulated, but practiced by few. It's an inconvenience to clean waders, boots, and boats after a day on the water, but it only takes a few minutes and goes a long way toward preventing the spread of aquatic invasive species. And while we may not know exactly what the impact of these species would be on our fisheries, it seems prudent to do what we can to avoid finding out the hard way. For further reading here are a few websites to get you started:

http://www.tu.org/science/aquatic-invasive-species-ais
http://protectyourwaters.net
http://stopans.org