It was long ago decided that this blog was to be guided by a few simple rules; that it would be family focused and friendly, devoid of rants or advice, and mostly my space to write about the
misadventures of my life.
Today, however, things are bit somber.
California’s fire season is shaping up to be one of historic proportions. The Rim Fire still raging near Yosemite Valley is one of 11 major fires currently burning in our bone-dry state. Those are only “major” fires. During the last few weeks, about 150 fires were sparked by lightning strikes. CalFire figures show that through the middle of August, 4,715 separate fires have burned the state — beating by a wide margin the historical annual average since 2008 of 3,000 fires. The Rim Fire is now the largest fire in the recorded history of the Sierra Nevada and, as of today, the 5th largest wildfire in California’s history.
In this moment, all eyes are understandably on the immediate danger to lives and property. Prayers are being said for the firefighters. This is devastation on an unimaginable scale.
As a fly fisherman, I can’t help but ask questions about the long-term impact on the many streams and rivers now stripped of bankside vegetation, and the fish in their waters. The extent of ecological damage won’t be understood for a long time. The intensity of the blaze — flames reportedly reached 100 to 200 feet as they shot up canyons — left nothing behind. While the Groveland Ranger District of the Stanislaus National Forest, the area predominately affected by the Rim Fire, has gone through cycles of intense wildfires, those fires have burned only small areas. (Decades of fire suppression and logging can be blamed.) Conjecture is that the Rim Fire, however, may have denuded up to a 1,000 acres.
The northern edge of the Rim Fire crossed the Clavey River, one of the longest undammed rivers in the Sierra Nevada, a designated wild and scenic river, and home to native coastal rainbow trout. The fire burned along extended stretches of the South and Middle Fork of the Tuolumne River as well as Cherry Creek, all waters known for fishing, whether stocked or wild fish. Many other but lesser known streams, streams I’ve found wild populations of trout, also fall within the boundaries of the Rim Fire.
Relatively little is known about the effect of fire on fish populations. An admittedly hasty search of the Internet offers some insight. It’s clear that the effects of fire on fish populations can be complex, with dependency on the length of the event, size of the habitat, the home range of the fish, specialization of spawning habitats and the type of fish. Of course, most studies cite salmonid fishes (trout, salmon, chars, freshwater whitefishes and grayling) as the taxonomic group slowest to recover after a fire.
That said, the effect of fire on native salmonid populations can be highly variable, with extinctions observed in some isolated small headwater streams, but a quick rebound when a species’ home range extends to multiple tributaries within a single watershed.
In affected rivers, streams and lakes, fires can most notably affect water temperature and water chemistry as well as the local invertebrates, amphibians and fish. No longer shaded by trees and brush, water temperature can rise, reducing the solubility of dissolved oxygen. Absorption of ash can increase the water’s pH and impact nutrient levels in aquatic systems. Studies document five- to 60-fold increases in phosphate, nitrate, and ammonium concentrations in streams affected by fires that have swept through larger watersheds. Conditions in these waters returned to normal with a few weeks, but were later impacted by rain flushing additional ash and soil through the watershed.
It’s likely that the smallest streams will have most dramatically impacted by the fire. Though most people dance around the issue, this has been another drought year for California, and water levels are so low that any longish exposure to the fire may have “cooked” many of those small streams.
Nature, however, can be resilient; as long as we don’t get in the way. Anyone who’s visited Mt. St. Helens National Volcanic Monument can attest to that.
A beetle native to the Sierras, which has infrared receptors allowing it to detect fire, could be first on scene to feast on the blackened trees. They, in turn, will draw birds. New growth will sprout, creating forage for small mammals and, eventually, deer and bears.
It just takes time. Though it may not look the same.
For a while, though, many Tuolumne County fisheries will probably be best left alone.