#990304 - 06/14/18 07:02 AM
Re: Another Step Backward
[Re: Great Bender]
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River Nutrients
Registered: 11/21/07
Posts: 7429
Loc: Olema,California,Planet Earth
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We have seen pinks, chum, cutthroat, and native char all respond by simply not being killed; lots escaped and spawned. While it is more complex than that, killing less will work. I find it hard to understand that PS conditions are so horrible and yet the cutts and char that live there year around increase. The pinks and chum spawn (in big systems) in the same place as Chinook. And yet, the FW habitat is not there for Chinook.
But, out in the Big Blue, the increase in pinks is now accompanied by a decrease in Chinook and coho. The pinks are also associated with decreases in some birds that breed in Antipodes but summer here to get fat. They (the birds) support a culturally important harvest on the nesting grounds. There is a critical problem out there with the food supply. Not only is there "not enough" but the quality is lower.
The solutions are going to require not only individual managers to get out of their silos but whole agency and county silos that look only at their parochial interests.
I would add, Tug, that we need more spawners in the habitat, period. Up in the Fraser, the majority of annual sediment transport in some streams is caused by spawning sockeye. Entrained sediment is the primary cause of low egg-fry survival. Seen any restoration proposals for sediment removal? Plus, here in WA it was shown that mass spawning by chum produced more fry than spawning at lower densities. Lower density gave more fry per female, just fewer in total. The management paradigm is to maximize individual yield (R/S, eggs/female) rather than total population. MSY-type management is based more on economics than biology; what is the minimum input I need to make to realize maximum returns. I don't think Mother Nature was an Economist.
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#990326 - 06/14/18 11:10 AM
Re: Another Step Backward
[Re: Great Bender]
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River Nutrients
Registered: 11/21/07
Posts: 7429
Loc: Olema,California,Planet Earth
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I think that pre-devlopment there were significantly more spawning salmon. The majority of studies that have quantified benefit of spawners directly feeding rearing juveniles (pink/chum feeding coho/steehead) seem to peak out at about 2 kilograms of spawner per square metre at SLF. Just plug that into something the size of the Skagit. We put 90K chum, successfully, into 2 miles of Kennedy Creek. The Stilly is how much longer??
We actually have seen these densities, and higher, in some streams. Whenever I have conversations with bios, they think-for example-that a million pinks in the Green was a lot and we should see huge ecosystem benefits. A million was a drop in the proverbial bucket and that is the disconnect. A manager looks at numbers and then tries to minimize the spawners to maximize the harvest.
I would add that when I started out, on a steelhead research project, that WDG believed a single pair of steelhead was sufficient to seed a mile of creek. So, the creek we were on was "adequately" seeded with 14 fish. Yeah.
As I noted above, if you want to clean the gravel, pack it with spawners. That has been shown to be the most cost-effective way to do it.
Edited by Carcassman (06/14/18 11:11 AM)
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