Posted by: stonefish
Oregon Steelhead Study
Posted by: cobble cruiser
Re: Oregon Steelhead Study - 12/13/18 03:43 PM
Uh oh, some environmental groups employees may have to take pay cuts now. 
Posted by: Anonymous
Re: Oregon Steelhead Study - 12/13/18 09:21 PM
Once a fishery is removed it is that much harder to get it back again in the same capacity. It's happening more and more equalling less opportunity . I loved summer fishing when I lived in oregon.
Posted by: Jake Dogfish
Re: Oregon Steelhead Study - 12/14/18 05:53 AM
Quote:
The summer Steelhead program ended in 1999 out of concern the hatchery fish might be weakening the wild run. However, the study concludes there was no corresponding increase in winter steelhead productivity after it ended. Wild numbers remained largely static until recent passage improvements in both the River Mill and North Fork dams over the past couple of years.
What a weak argument! You could literally make this excuse for anything that is harming salmonids. It’s just like closing fishing or removing nets etc. If the runs don’t improve then it proves fishing made no impact.
Or does it???
Posted by: Carcassman
Re: Oregon Steelhead Study - 12/14/18 07:23 AM
It shows that the hatchery program was not what was controlling the winter numbers. You are right, Jake, that if you close fishing and nothing happens then something else was holding down the run.
It is necessary to have significantly better monitoring than we now do because the stocks have way more impacts. Coho and steelhead, in an ideal situation, seed a stream from the top down. An escapement of 1,000 fish that spawns 50% of the creek produces half the smolts of a 500 fish escapement that spawns the whole thing. Been there, done that, counted the fish.
A steelhead stream produces more smolts when the smolts are younger and they are younger when the productivity of the stream (nutrients) is increased. Again, fewer spawners may produce more returning adults.
In this situation, something other than the stocking of a segregated summer steelhead stock was holding down winters. In a different OR stream they laddered a barrier that allowed winters into an area previously occupied only by summers and the summers declined due to competition for rearing area. Stop passing winters, and the summers rebounded.
It may feel good to stop releasing hatchery fish (known to be the evil spawn of Satan) but sometimes they are not the problem; just the easiest action.
It appears in the this situation that passage was the problem. The question that should be asked is can we put a segregated summer program back in? If it does no harm, then why not?
It is necessary to have significantly better monitoring than we now do because the stocks have way more impacts. Coho and steelhead, in an ideal situation, seed a stream from the top down. An escapement of 1,000 fish that spawns 50% of the creek produces half the smolts of a 500 fish escapement that spawns the whole thing. Been there, done that, counted the fish.
A steelhead stream produces more smolts when the smolts are younger and they are younger when the productivity of the stream (nutrients) is increased. Again, fewer spawners may produce more returning adults.
In this situation, something other than the stocking of a segregated summer steelhead stock was holding down winters. In a different OR stream they laddered a barrier that allowed winters into an area previously occupied only by summers and the summers declined due to competition for rearing area. Stop passing winters, and the summers rebounded.
It may feel good to stop releasing hatchery fish (known to be the evil spawn of Satan) but sometimes they are not the problem; just the easiest action.
It appears in the this situation that passage was the problem. The question that should be asked is can we put a segregated summer program back in? If it does no harm, then why not?
Posted by: Salmo g.
Re: Oregon Steelhead Study - 12/15/18 11:30 AM
Wow, that's an impressive report. I must admit I got bogged down in the statistics. They use some that are above the level I ever got to in undergrad school. I don't lament the Kostow study so much; this one has a larger data set and takes a deeper dive into ocean survival variables. Interesting that they found no correlation with May upwelling, which intuitively seems influencing to me, yet did find a correlation with May PDO. Kostow looked at PDO for the period of ocean residence, which in more intuitive and makes sense as a variable affecting total marine survival. Who'da' thunk to examine May PDO as a discreet independent variable? Probably not me.
This report doesn't have all the answers either, but it's important. I've figured all along that the presence of hatchery fish doesn't do any favors to wild fish, but I haven't thought the hatchery fish are a limiting factor either. Looks like they aren't, at least in the Clackamas. I think that's the case in most WA streams as well. The problem with hatchery steelhead in WA looks to be that they don't return enough adult fish to justify the expense of having them as a taxpayer and license funded program.
This report doesn't have all the answers either, but it's important. I've figured all along that the presence of hatchery fish doesn't do any favors to wild fish, but I haven't thought the hatchery fish are a limiting factor either. Looks like they aren't, at least in the Clackamas. I think that's the case in most WA streams as well. The problem with hatchery steelhead in WA looks to be that they don't return enough adult fish to justify the expense of having them as a taxpayer and license funded program.
Posted by: Carcassman
Re: Oregon Steelhead Study - 12/15/18 12:29 PM
There was a study out of OR, on the OPI coho that was really instructive to me.
They found a nice 4-variable model that explained most of the variation in marine survival for a cohort. The problem was that the 4 variables were temporally sequential, such as (I am making this all up) upwelling when they entered the ocean, PDO in late summer of first year in salt, spring upwelling, and summer ocean temps.
The described what happened but ween't good as forecasts because any one of them could overwhelm the others. The first 3 were "bad", the last "good" and you get a good run. But, that last piece of information is available just before they enter the terminal areas where updates could be done.
This may explain why the forecasts we base ocean fisheries on work so well. Conditions late in the return can overwhelm what went before, knocking numbers either way down or making them be higher than we planned for. Just another reason to manage terminally.
They found a nice 4-variable model that explained most of the variation in marine survival for a cohort. The problem was that the 4 variables were temporally sequential, such as (I am making this all up) upwelling when they entered the ocean, PDO in late summer of first year in salt, spring upwelling, and summer ocean temps.
The described what happened but ween't good as forecasts because any one of them could overwhelm the others. The first 3 were "bad", the last "good" and you get a good run. But, that last piece of information is available just before they enter the terminal areas where updates could be done.
This may explain why the forecasts we base ocean fisheries on work so well. Conditions late in the return can overwhelm what went before, knocking numbers either way down or making them be higher than we planned for. Just another reason to manage terminally.