It was quite the explosion of beaver supporters crossbred with salmonid workers today at the workshop for beaver/steelhead & salmonid interactions. What a fine pedigree of people attending displaying a wealth of knowledge at the intersection of all things anadromous, finny, furry, and buck-toothed. The building itself is the spanish villa styled senior center on the waterfront in beautiful Santa Barbara CA. Only a stones throw from where I live in Oxnard CA I was able to drive there. Lucky me as others attending came in from as far away as Massachusetts!! This was the first workshop of its kind put on by the salmonid restoration foundation and as far as I know the first seminar/workshop highlighting the juncture of beaver and anadromous fish.
The first talk was by Rick Lanman (Institute of Historical Ecology), who spearheaded the recently published paper on the historic range of beaver in California. It was a well executed speech, also getting into some of his past work on beaver dams in the high sierra. One thing that was new to me was how important the steel trap was in extirpating beaver. And this extirpation, Lanman maintains, was not always committed by English and Russian fur trappers- but by the native Americans who got access to this deadly new technology. Rick also went further into the interesting semantics that for so long confused historians looking at the historical record for beaver clues. Spaniards referred to beaver as las nutrias- Spain itself having had its population of beaver long extirpated -not as Castor. The Spanish wrote of nutrias marinas- sea otters -and fresh water nutrias- which you might think implies fresh water otters -except that the record for fresh water North American river otters south of Monterey Bay is... nonexistent, and that leaves you with beaver. Not to mention the fact that these nutrias were described as dam builders. Well done Rick and coauthors, a job well done.
Eli Asarian (Riverbend Sciences) dovetailed into a discussion on the current distribution of beaver in California. He is a coauthor on the Lanman paper and works primarily in northern Californian watersheds. Eli presented loads of nice pics on beaver dams as well as presenting some data on juvenile coho/steelhead using beaver ponds as rearing ponds. Eli also has done some crucial work spearheading beaver mapper, an invaluable tool allowing scientists and citizens to document beaver sightings and document their expansions. He also hinted at some new and exciting work on beaver and salmonids coming down the pipeline!! Good job Eli!!
Next up was Heidi Perryman of Worth a Dam and Martinez Beavers. I also like to call her the CNN of beaver because she is a bit of touchstone for all things beaver. Her presentation was basically a summary of the 6 years of citizen science that she and her group have been doing in Martinez CA. I like that she took a stand and said we are not tagging these beavers. Plenty of good observational science can be accrued without alien abductions, I mean tag and release studies!! Thanks for coming down and presenting Heidi!!
The next speaker was Michael Pollock, a heavy hitter in the world of beaver/salmonids and is one of only a few published authors looking at this interaction. He gave a nice review of our knowledge of the interaction of beaver dams and salmonid passage and basically concluded... more research is needed. How very sciency of you Michael, just kidding- his talk was basically favorable to beaver and salmonids cohabiting, especially coho and steelhead being the best jumpers. But in addition to jumping salmon can swim over and around dams with appropriate flows. He also made a very pertinent statement regarding watershed health to paraphrase: the more complex, the more difficult to measure a habitat is, the healthier it is. Chew on that one kiddies. For me that means if a watershed has deep quiet pools, fast ripples, side channels, ox-bow lakes, deep parts, shallow parts all jumbled about and mixed together that is a good system. And beaver can help in those regards. One thing that Pollock stated that did get my attention is the concern that beaver dams might hold-up or delay downstream migrating smolt. While in some populations/species I can see why this is a concern, in the case of the southern steelhead, a unique population of steelhead and the most behaviorally plastic of all steelhead I think that this presupposition warrants further analysis. Let me elaborate: It is now generally understood that downstream migrating southern steelhead get through the main channel, which may usually go dry in socal, and arrive at the lagoon/estuary often times blocked from the ocean by a beach berm. They then come to size in the relatively rich feeding ground of the estuary and move into the ocean when the
time permits. However, as recently happened in the santa clara estuary, if these estuaries are breached prematurely steelhead might be left high and dry. My point is that if downstream migrating smolt found a beaver pond to their liking- that gives them another option besides the estuary to grow up in. Something to think about...Next up was Tim Robinson, MC for the event, and also the man tasked with balancing the needs of the citizens of Santa Barbara county, Cachuma reservoir, fish, agriculture, difficult landowners, invasive species, and beaver on the Santa Ynez watershed. His was the most guarded speech as goes the benefits of beaver to highly modified, Mediterranean climate watersheds. From his perspective I can see where he is coming from. The Santa Ynez river is a little strange in that Lake Cachuma, a man made reservoir, effectively cuts off half of the watershed to steelhead. What is left is the main channel and several tributaries, most notably Salispuedes creek as steelhead habitat. Due to the inability of steelhead to get up to the majority of their historical spawning grounds Tim and the Cachuma water group are trying to maintain the main channel of the Santa Ynez as a habitat for steelhead spawning. And as you may know this is not really how the southern steelhead works- the main channel is simply the avenue used to reach tributaries for spawing. So criticisms that beaver dams spread non-natives, warm the water, or spread sediment in the main channel really fall a little flat in light of the fact that steelhead don't treat the main channel as the spawning grounds- they want the cooler mountain tributaries. Secondly the other indictment on Santa Ynez river is that flows are not reached that blow out the beaver dams. Again, in this modified system, Lake Cachuma absorbs a lot of these flows so that the full potential fury of this river is never reached as it would if the dam was not there.
Cheers!!
Support me on Patreon.
Like antediluvian salad on facebook.
Watch me on Deviantart @NashD1.Subscribe to my youtube channel Duane Nash.
My other blog antediluviansalad.blogspot
Great post and excellent points. I loved the map given , but found many regions left out like the San Luis Rey River from Lake Henshaw to the ocean. I have seen numerous beaver signs there ever since I was a kid in Scouts in the 1960s.
ReplyDeleteI actually have saved some interesting research findings and observations for which I should actually finish my last Beaver post. The interesting movements of beaver to newer areas over long distances on land is intriguing. Warner Springs and Ranchita area are two examples.
Are you referring to the beaver mapper? You can add your sightings to that map I believe or contact eli@riverbendsci.com who does the california beaver mapper.
Delete