There are quite a few salmon rearing pens here in WA with to the best of my knowledge all run by private groups or tribes.

Do any of the active or retired biologists on this Board know of any research which has looked into how those pens affect rate of adult returns? Or of any folks currently active in our fisheries who might be a resource on this subject?

Not lately, but there have, and likely continue to be, a lot of marked groups released from net pens. My understanding is that survival is pretty good because of the larger size when the young fish are released. Larger size at release almost always correlates with higher survival rates.

Not a bio, but would any of the CWT data available on the WDFW website give some insight on success or lack there of regarding some of the net pen programs?

One thing to consider with that data though is how many fish are tagged compared to the total number released. Maybe a 5% tag rate is enough to provide good data to measure success for some programs?
Good question and I'd like to know as well.
SF

As Salmo said, there is a whole lot of data regarding their effectiveness. Back in the heyday of net pens they were popular for the good marine survival rates. Even more so was for the behavioral changes. Chinook and coho both tended to stay in the Sound, giving rise to the year-around fisheries. The fish tended to be smaller at age due to differences in food, but they were the backbone of those fisheries. They also provided concentrated fisheries on the adults so there was a rather intensive fishery (net) for the Deep South sound coho but because they were concentrated the wild coho returning to locally could be more easily avoided.

Larry,

There was a review of the WDFW PSRFE (Puget Sound Rec Fishery Enhancement) programs back in 2018. The review data is mostly from the late "aughts" and mid teens. But there are some good longitudinal survival % graphs, for net pen releases going back into the 70s. Spoiler alert: They have been way down since the 1990s.

Anyway, there may be some additional info for you here:

https://wdfw.wa.gov/sites/default/files/...vember_2018.pdf

Thanks guys. I will be doing some reading for sure. For the most part these pens are for Coho although the one located at Pt. Defiance has been receiving Chinook from two sources. The Chinook have had CWTs which have been unique to each of the two sources.

None of these fish have been held past normal out migration from theSound unlike those intended to generate more resident fish for the winter blackmount fishery.

My interest is to find out if those acclimation net pens generate adult returns exceeding the returns of the same stocks released from directly the hatcheries. Presuming that there is are increased rates of return then how much and is it cost effective?

Again, so far these pens have been heavily supported by volunteer effort.

Larry B, are you looking for evaluations of what we used to call coop programs that operated small net pen release sites, generally out of marinas? (As opposed to the larger programs that are reviewed in the document that JustBecause sent) If that is the case, I doubt that you will find many, if any. Those programs were just assumed to be successful, without any real tagging or evaluation. For many years that was common even for some of the larger programs. And your comment that "none of these fish have been held past normal out migration time from the Sound" needs some clarification as well. Most of the net pen programs for Chinook were not really delayed release, but rather release of yearlings versus fingerlings. They were released at the normal time for yearling releases. Just that change, at one time, had the effect of changing the migration pattern to produce more resident fish. There was also anecdotal information that the fish returned more to the release site rather than the source hatchery, but without tag recoveries you couldn't really say much more than that since no one could really determine where they ended up.

Yes, it is the "coop" programs in which I am interested in trying to find comparative rates of adult returns between fish released directly from the hatchery and same source stock transferred to short term acclimation pens.

The Point Defiance program has had fish from both the tribal hatchery and WDFW and some/all (not sure of %) have had CWTs implanted for tracking purposes.

FYI at least some of those fish have made their way back to their respective hatcheries.

It would be of potential value to be able to quantify any improvement in adult return rates to assess whether such improvement is worth the costs.

Maybe some PhD candidate needs a research project.

Are you looking at adult returns just to then pen site or to the hatchery? Unless the hatchery is located close to the mouth of the hatchery watershed the fish will have a gap in imprinting and may stray more. I know WDFW had a series of CWT'd coho out of Westport Marina pens that were supposed to look at how source hatchery affected return to pens. Many felt that if Hump fish were used they would just turn left up the Hump instead of right to the pens while fish from Satrap would at least visit the pensite first.

There is an aspect of using the pens that may help adult survival. The acoustic tags that have been used (mostly on steelhead in WA but other species elsewhere) showed a rather significant loss on downstream migration before entering salt. This loss occurred both in hatchery and wild fish and at similar rates from the data I saw. It also occurred in wild coho on only a 3 mile migration. Point being that releasing fish from the pens misses this loss. I have only seen FW data and I don't know if anybody compared an acoustic release from pens with an acoustic release from a stream.

There is a lot to be learned from passive tagging (acoustic) where the fish does not need to be killed to recover the data. I was surprised at the level of loss on the downstream migration.

Starting with the predator avoidance benefit there is also the presumption that fish in the acclimation pens are being fed with quality food and being fed regularly with the result being they are better prepared than their natural origin and hatchery released brethran.

So the questions are (1) do the fish out of the acclimation pens actually have a better rate of adult returns and, if so, (2) what is the magnitude?

For example, if the accepted rate of adult return is 1% and the acclimation pen fish achieve a 5% rate of return is the acclimation pen a good investment? That question becomes even more pertinent when critical stocks could be given the benefit of an acclimation pen.

While most of the "coop" operations are relatively small it is noted that the Muckleshoot tribe has an acclimation pen in Elliott Bay that has held abound 900K Coho annually and has been operating that pen for years in conjunction with the Port of Seattle.

It gets complex because survival is measured at different beginnings. From the data I have seen, if you released the same number of smolts from Soos Creek, Icy Creek, and the old WDG site further upstream (I forget the name) Soos would put the most fish into Elliott Bay, Icy next, and WDG third simply because of FW migratory mortality. Now, we need to know what marine survival is for each group from the same start point.

Once we know what the rates are and where mortality occurs we can fully evaluate the programs. Where do catches occur? If they are, say off the West Coast of Vancouver Island while the other puts fish into Puget Sound it might be better to feed WA anglers.

Another aspect is if a lot of fish come back, but the don't bite, then they will end up in nets or as excessive surplus. At some point, we have to evaluate how much it costs to put a fish in the net, a fish on the hook, or a fish on the gravel.

Over time, some of these points have been looked at but I think a lot more needs to be done. That is, if there as intent to raise fish to put into creels.

How much it costs per fish at any of those three points is worth looking at but that leads to the trap which was one of the big nails in the winter blackmouth fishery; cost to produce a harvested fish.

If one is looking at costs one should also look at value. For example, how much effort (fisher trips) is put into catching a blackmouth or a steelhead? It has been a few years since WDFW paid to have a study and report accomplished citing the economic value of a day fishing in several local fisheries.

C-Man znd Larry, I respect your comments, but all of us know how to calculate the cost of our fishing. Someone said that it is a fool who knows the cost of everything, but the value of nothing. And I believe that idiom is the driver of too much in our lives. I know that I've spent a small fortune chasing steelhead and salmon because that's what I love to do. And love is a key word here. To give "Value" a perspective to a younger friend of mine, recently retired, he's just ordered a new $150,000 aluminum boat that's designed only for fishing, no over night accomodations, etc. He's doing that because he loves fishing and a family fishing experience. I think we can have wise fishing and hatchery management (we don't), but can much better pursue a better quality fishing experience if we keep trying.

I think you're onto something Tug when looking at the value an angler/hunter puts into their sport. Pretty sure WDFW doesn't consider it because they don't get anything from it; the taxes (sales and such) go to GFS. I think, too, each of us has our own view of what opportunity is and I know mine is not mainstream.

How do you propose WDFW prioritize hatchery production? Since it is heavily subsidized by license/DJ then I feel the majority should go to recs. Tribal and commercial should be funded by GFS. But those $100 per fish in the creel programs seem misdirected to me.

What I would like to see is some sort of mandate, based on funding source, as to where the fish end up in the catch. Such as, Minter Creek will produce fish to support X, Y, and Z fisheries at Q levels. Know what you're getting going in. Have measurable outcomes.

If managers make decisions solely upoon the cost to produce a fish in the boat and (purposely) fail to consider the value of that same fish it would seem to me that they are finding a way to reduce or eliminate a program.

I don't know how much things have changed since the 00s, but back then the only thing guiding the Fish Program was saving money. The less spent the better.

I would add that one needs to more clearly define "managers". The people who manage the money are not those who manage the fish. The fish managers play the hand dealt by the money managers. Or used to, anyway.

FYI, most of the net pen (NP) programs in Puget Sound are funded with PSRFE funds (save for the South Sound and Elliot Bay coho NPs), which is a dedicated funding source from the legistature to enhance marine rec fisheries, so can't be used for other things that WDFW might want to do with it. Hence why I included the PSRFE review report earlier. Over the decades, the effectiveness of the NP program fish to residualize in the Sound (main origina purpose of the PSRFE program - winter/spring marine salmon fishing) has decreased (see report above) so the added cost of delayed release Chinook has not been as pracital as it was in the 1970s and 1980s. Many of these dollars have been used to increase on-station production of sub-yearling Chinook, as the rate of contribution to blackmouth fisheries has been shown to be as high as NPs and the numbers of fish released in also substantially higher for the same dollar. Coho has been more of a mixed bag of performance, so there are still more coho netpens than Chinook.