September 29, 2004
Of Bull Trout and Purple Loosestrife
I love to travel in September, but normally, like most academics, I can’t. Since I’m on leave this year, I decided to seize the chance and take off with family members for a trip to the Canadian Rockies to celebrate (if that’s the word) my 40th birthday.
I found myself mulling over whether it would be possible to just chuck it all and move to Jasper, Alberta. It was an amazing trip—the first real “vacation” I’ve taken in a long while, where I wasn’t attending a conference or looking at an archive or something similarly productive. I love the mountains of western North America in general, but the landscape between Banff and Jasper trumps everything else I've seen.
One thing that I did find surprising and disappointing was that the fishing wasn’t terribly good. A bit of that was the time of year, and a bit of that was that we were in the wrong place to fish some very productive waters (the Bow River around Banff isn’t nearly as good to fish as the Bow River south of Calgary) or we didn’t have time and inclination to fish the way we ought to fish (we tried shore-fishing at Lake Maligne above Jasper, when you really need to get out in a boat and troll the deep water). Also, the fishing had just closed at a few places.
Still, there were waters that looked to me as if they should have been good trout waters, both small lakes and rivers, but turned out to be pretty well devoid of fish. I did a bit of snooping and found out somewhat to my surprise that Parks Canada is aggressively anti-stocking and has been ever since 1988. This explained in particular why some small lakes that have no outlet or inflow (like Horseshoe Lake near Jasper) were devoid or nearly devoid of trout.
The purpose behind Parks Canada policy appears to be two-fold. First, to remove trout from aquatic environments within the National Parks where non-native predatory fish are deemed destructive in their impact on the ecosystem; second, to protect native species like the bull trout and the cutthroat trout.
The first objective I can see—it’s easy to forget that the introduction or repeated re-stocking of trout into waters that wouldn’t normally support a trout population has a significant impact on other organisms, like amphibians, particularly if the water is cold enough for the trout to reproduce.
The second objective I feel a bit more ambivalent about. If rainbow trout elbow out bull trout, then that’s a problem from the standpoint of losing a species of trout, but on the other hand, rainbows pretty well occupy the same niche as bull trout, only more successfully and possibly voraciously. The vision here isn’t just the preservation of a species—it’s the larger antipathy towards “invasive species” that’s become an orthodoxy of environmental science.
I do wonder about that attitude a bit, not just in the context of fishing, but as a whole. When I read some of the material on the dangers of invasive species, its rhetoric and tropes sometimes seem uncannily familiar, reminding me very much of ideas about race, miscegenation and nativism in modern colonialism, in post-colonial nationalism, and in identity politics. There’s some similar desires to stop the forward motion of change, to fix environments (human or natural) in their tracks, the same suspicion of dynamism. What is particularly striking to me is that the arguments against “invasive species” even from scientists sometimes seem not so much technical or scientific (when they are, they usually rest on the relatively weak assertion that there is a burning necessity for general biodiversity that trumps all other possible principles of ecological stewardship) but mostly aesthetic.
There are practical concerns posed by some invasive species, to be sure. Nobody wants zebra mussels in their waterways. More importantly, I readily agree that an introduced species which might appear harmless or inoffensive can have unpredictable effects on an ecosystem. It’s a classic source of emergent change. But what’s interesting to me is that the strongest general attacks on all invasive species frequently concede that it’s impossible in general to predict the full long-term consequences of a species introduction, and indeed in many ways impossible to predict or manage the long-term arc of change in any ecosystem even assuming that all introductions of new species could be prevented. I wonder then why there is such certainty, therefore, about the horror of any and all species introductions.
Breeding populations of animals do move around even without human assistance, after all. This is a basic part of the natural history of life. It’s the pace and scale of the phenomena that has changed, and that obviously has serious implications. But when ecosystems actually endure what we’re told is a fatal threat, one has to wonder whether we don’t need to be more discriminate and dispassionate about the phenomenon. Say, for example, the way that some places are trying to fight purple loosestrife and predicting environmental disaster if it gets established—but purple loosestrife has been around since the early 19th Century in the East Coast, with some complicated but hardly apocalyptic consequences.
I wonder then for the same reason whether it is really so terrible if rainbow trout displace bull trout in waters that support trout populations. There are consequences to that—loss of genetic resources of the bull trout population, possibly pressure on prey populations due to the more voracious appetites of the rainbow trout, and loss of the unique “character” that bull trout provide, whatever that might be—but the intrinsic, instictive horror at the idea of a “native” species displaced by a very similar “non-native” one seems to me to come largely from the same place that modern ideas about race, identity and nationality in human beings have come from, somewhere deep in the cultural and ideological foundations of modernity and not from a cleanly rational scientific principle. There's a rich potential intellectual history lurking in there somewhere--in fact, I strongly suspect that it's already been written, and I'm simply not aware of it.