Leave it to beavers to help salmon?
Although seen by some as a nuisance, the North American beaver (Castor canadensis) may prove to be a misunderstood ally in the field of riparian habitat restoration. Recent research has shown a linkage between regional declines of both salmonid and beaver populations. Dr. Michael Pollack of the National Oceanographic and Atmospheric Administration has studied the relationship between beavers and juvenile salmon for over a decade, with his first paper on the subject dating back to 2004 (Pollack et al. 2004) His research suggests that beaver ponds, like those found in the Stillaguamish River Basin in Washington, can benefit the river ecosystem as a whole.
By creating ponds, beaver dams enhance rearing and over-wintering habitat that can shelter juvenile salmonids from high flow events. Studies conducted in streams along the Oregon coast suggest that the survival of juvenile winter-run Coho salmon (Onchorhynchus kisutch), which can be swept downstream by increased winter stream flow, depends on adequate slow-water habitat. The readily available food and protective environment in beaver ponds lead to increased salmon growth and survivability. Beaver activity can take a bite out of woody riparian vegetation, but in turn it increases the input of large woody debris to streams, which provides in-river habitat for a wide variety of species. Riverside beaver dens have the potential to increase erosion by reducing riverside vegetation. However, the sedimentation that accumulates in the ponds over time can also reduce the volume of material washed downstream that could impair downstream habitat. A study conducted in Wyoming showed that sediment loads were decreased by as much as 90% after flowing through an area with well developed riparian habitat and beaver dams.
Great beaver promotion from some new friends at Fishbio in Oakdale CA. They monitor salmon passage with fish weirs on the Tuolumne river and have seen the number of beaver passes go way up. I’m not sure what nudged them into the beaver-light recently, but I was alerted to this by someone at my recent SARSAS talk, and the trout talk, so maybe things are cross-pollinating. I was a little anxious when I saw how close they were to the beaver-killing county of Merced on the map, but they are in Stanislaus County, which is one of the least lethal for beaver, only 50 depredation permits issued in the two year period we reviewed.
So whether you’re a beaver or a salmon: remember it’s better on the Tuolomne.
No kits last night either, but we did get to see that mom is deeply fond of apples and still sporting healthy teats. I’m thinking they’re looking a little less full so that has to mean we’re very close to a kit appearance. A weaning kit is a hungry kit looking for branches, am I right?
