Local Conditions and Life History

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FromTheHills

New member
Joined
Feb 9, 2009
Messages
9
Location
Corvallis
Although we had some pretty wet weather around Christmas and New Year's, it's been pretty dry since then. On the USGS gauge, the Siletz is currently in between the 10th and 20th percentile of flows-- meaning that only 10-20 percent of a discharges for the past 30 years of flow data, for this time of year, has been equal to or below this number. In other words, Oregon's rivers are running low, pretty darn low for more than a month. Low flows are seen throughout the Willamette basin and coastal streams.

So, are the winter steelhead runs matching the predictions?
ODFW's 2009 Winter Steelhead Forecast

I recently quizzed some biologists about the effects of low flows on the winter runs. In the Yaquina system, for example, the word is that the fish are still stacking low because of decreased seasonal flows.

Here' some info I pulled up from research from UC Davis, just out of interest:

"Adult steelhead movements are most rapid and uniform when the hydrograph is either falling or rising. However, as a declining hydrograph drops to certain low levels, there are distinct thresholds at which adult movements begin to slow and then eventually stop altogether. As these thresholds are crossed, more and more fish end up “stacking” in certain “favored” pools and runs."

"...spatial distribution of spawning can and does vary widely between years and even within the same year. The controlling mechanism appears to be flow, with adult steelhead very definitely “going with the flow.” For example, in overall high-flow years (e.g., 2006), spawning is focused in uppermost stream reaches that fish are able to access, including areas only rarely utilized. In overall low-flow years, much more spawning occurs in higher-order downstream reaches, including the main stem of the river. However, within any given season, a shift to more spawning downstream can and does occur when the river hydrograph is in rapid decline, or the end of the spawning season (i.e., roughly mid-April to mid-May) is nearing."

"During the majority of the spawning season, from roughly December through March, a single stacking and holding event, due to low flows, may last weeks or even months. Invariably, a freshet will occur, however, sending fish on their way up- and down-stream. However, in April and May at the end of the spawning and rainfall seasons, there is a “tipping point” during prolonged low-flow periods, beyond which adults leave places where they are stacked and begin moving out of the river system; this occurs despite the difficulties (i.e., physical barriers) and risks (due to increased predation). The tipping point phenomenon likely occurs in response to increasing day length and water temperatures, and is why very few adult steelhead become trapped in the river over summertime in most years."

So, do a rain dance and they will come??
 
G

GraphiteZen

Well-known member
Joined
Mar 21, 2008
Messages
2,140
Location
Corvallis, Oregon
Nice post!

Can I ask how you tracked down the information? I try to find the same type of stuff on the net but have some difficulty.

Also, if the entire paper you pasted from is on the net could you post a link?
 
A

ArcticAmoeba

Active member
Joined
Jun 5, 2008
Messages
973
Location
Oregon
You are not a dork. You should see my fishing logsbooks. I have well over 70 college rule Pen-Tabs. All are stacked to the brim with logs of hooked fish, boated/banked fish, and retained fish. But some are just short, usually random bits of fact/information/theory I have recorded from hearings, dialogues, seminars, but mostly, conversations with a few certain people on the ragged edge of the Federal, and State fisheries commissions. It is interesting to see how others go about information gathering, and recording. Google Scholar is a great resource. When I want to find quality, mostly up-to-date information, I turn there to get relatively un-biased works from research groups, and universities especially, as their end goals are usually, purely science/biology based. To think like the fish will yeild better results when targeting them. To think like a fish you have to get to know them in the most interesting ways. Knowing general biology, and habits is the first step in a great direction.
 
F

FishFinger

Well-known member
Joined
Jul 27, 2008
Messages
1,217
Location
Central Oregon
Outstanding post, thank you for the plethora of fantastic info.
 
Raincatcher

Raincatcher

Moderator
Joined
Apr 15, 2008
Messages
4,705
Location
Less than 50 feet from the Santiam River! :)
Not a dork

Not a dork

FromTheHills;
No,you are certainly not a dork! I love it, when you answer a question, you don't leave out the details that are often the meat of the entire answer. Thank you for the time and energy your contribution surely took.
By the way, welcome to OFF! I must have been out sick when you signed on. I think we are going to learn quite a lot. Glad to have you here. Be safe.
Barb
 
B

bir48die

Member
Joined
Feb 7, 2008
Messages
32
Location
Beaverton
This is good info. Plus, I'm headed to the Siletz next weekend to fish the headwater. We'll see if some of those Steelie's are stacked up.
 

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