We use a short range DIDSON in Redwood Cr, and a long range ARIS in the Mad R. Redd surveys are independently counted in Redwood Cr. To date (3 yrs of data), we are not seeing any agreement with sonar counts and redd counts for Chinook salmon and steelhead trout. The redd counts are negatively biased, even if you take into account that not all salmon passing the sonar beam will spawn (pre-spawn mortality). I know there is similar work on the Secesh R in Idaho, and I am wondering if any other place has a similar study going on and what their results might be.
Michael,
Michael Connerton of the NYS Department of Environmental Conservation has several years of hydroacoustic Chinook salmon counts in the Salmon River, and I think a grad student may have conducted redd surveys during one of those years. Mike's e-mail is : [email protected]
Good luck,
Steve
We contract annual redd surveys of spring Chinook salmon through Oregon Department of Fish and Wildlife. I PM'd you the POC as well as a DRAFT report. Typically to estimate the escapement for a reach the redd count is multiplied by 2.5. This conforms to the negative bias you are seeing. However, we don't have DIDSON monitoring, and instead use the video counts at barrier dams.
What is interesting is that the productivity and effective population size of fish transported above our projects can vary widely by watershed . We are monitoring this through parental based genetic studies. In one basin we transport over 500 adults yet the number of individuals contributing to the cohort for that brood year number lass than 100. This is likely due to a combination of PSM and losses during incubation. It is likely that the interbasin variation is likely due to the hydrological and geological differences. Our lowest performing subbasin has the combination of large floods during incubation, combined with a river channel that has a lot of bedrock.
We also have done a lot of investigations into pre-spawn mortality which I can provide if it would be useful.
v/r,
Griff
Thanks David, very interesting. I am new to research post, what does PM mean? We have flood events here that can devastate Chinook production as well (unregulated rivers that I work in). I would like to read the papers you mentioned, including pre-spawn mortality. Hey, do you know Bernard Klatte (he works for USACE out of Portland too.
PM = Personal Message
Check your inbox and see if it got there, if not we will figure out a different way. I know Bern and work with several of his staff frequently. Small world!!
East Bay Municipal Utility District uses video, redd surveys and carcass surveys on the Mokelumne River, CA and Tri-Dam.USFWS and CDFW use Vakki, redds and carcass surveys on the Stanislaus River. - JM
Michael,
There are many years of data available for fall Chinook salmon escapement vs redd counts for the Hanford Reach of the Columbia River. Despite problems related to imprecise escapement estimates (visual/video counts from dams - confounded by a variety of factors - primarily unknown fallback rates) and inability to detect deep water redds (visual counts from fixed-wing aircraft), there has been a fairly consistent relationship between estimated escapement and redd counts. The link (if it worked) is to a tech report that presents some of this info in the discussion. I can put you in touch with folks who may have more up to date data on this if that is of interest.
Cheers,
Geoff
Technical Report Chinook Salmon Escapement and Spawning in the Priest Rapids ...
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