Natural-origin Salmon Abundance:

Analyzing large-scale conservation interventions"

Summary: A recent study that compared 12 wild chinook salmon populations that had been the focus of hatchery supplementation programs and 10 populations of salmon that had never been the focus of supplementation programs found none to small benefits in natural salmon abundance.

The study analyzed information from a 25-year period and determined that densities of natural-origin spawning adult salmon in the Snake River Basin that had been the focus of supplementation programs had increased just 0 percent to 8.4 percent relative to the 10 salmon populations that had not been the focus of supplementation.

There could be several explanations for this, according to the study.

First, other studies have denoted the poor reproductive success of hatchery salmon and they could depress the abundance of wild adults, as well.

Second, the theoretical basis of supplementation assumes that target populations are well below carrying capacity, the study says, and the lackluster performance of supplementation shown in this study could be because populations are closer to carrying capacity than thought.

As time goes on, I'm increasingly convinced that the brutal reality of our fisheries situation is that we have compromised fish population carrying capacity far more than we thought we have. Among the stream rearing obligates of chinook, coho, and steelhead, harvest has pretty much been taken out of the equation south of latitude 49. Across the board, what's left but habitat productivity and capacity?

Marine environment and associated low smolt to adult survival.

has anybody studied the effects of supplemental feedings in stream?

can adding trout chow to the environment increase the overall population? will the larger population then sustain itself due to the larger nutrient base?

To play devil's advocate:

Someone once defined insanity as doing the same thing, over and over again, and expecting different results....

We model our salmon fisheries to kill every salmon, wild or hatchery, above established escapement goals. While we don't always do as well predicting how many fish will be available, we do a pretty fair job of harvesting down to the last paper fish. I think it's safe to say that in the modern era, escapements well above the floor are viewed as management failures. Evidently, our managers aren't failing very often in that regard.

It seems like more and more science is pointing the finger at habitat as the primary limiting factor in salmon abundance. It would be pretty arrogant (and misguided) for someone like me to say the science is fatally flawed, so I'll stop short of that, but I think it may be incomplete.

I recall from high school chemistry that any good experiment contains a control sample. If the hypothesis states that harvest is not a leading factor, shouldn't the observations include what happens when harvest (and I don't mean just in-river sport harvest) is removed from the equation? I realize why that experiment has not been conducted, and for the same reason, it's not likely that it will ever happen. I guess my point is that politically-tainted science, while it may yield results that help fisheries managers sleep at night, probably fails (often by design) to reveal the whole truth.

One more thing... Whatever the verdict on harvest, I think we all agree the ocean is a huge part of what determines overall abundance. It seems pretty clear that when we enjoy above average returns, we have the ocean to thank for it. Unfortunately, there is next to nothing we can do to control that. However, if ocean conditions are the reliable predictor of relative abundance we have come to understand they are, shouldn't we adapt our fisheries models to reduce impacts during years of low ocean survival? Well, as it stands, we don't do that. Instead, we continue to fish right down to or below escapement. Then we have to ask why hatchery supplementation isn't increasing wild abundance?

Salmo can correct me if I am wrong, but here is my take on the experiment you propose. There are several control populations in this experiment already. Those are the ones not supplemented. The test populations were supplemented and the general result is very little change. As far as harvest effects (again, Salmo, check me out), these are Snake River Spring/Summer Chinook that for all practical purposes have zero ocean harvest, so the in-river harvest is all you have. Between 1979 and 2013, the total in-river harvest rate ranged between ~4% and 17%, and in fact in some years fish were left on the table. Given these figures, it's really hard to argue that changing harvest would have any effect since harvest is already very low and since putting additional fish on the spawning grounds (through supplementation) had little effect. Obviously this doesn't address any potential reduction in productivity from hatchery fish, but just about everything that I've read suggests that even hatchery fish will produce well if there is a lot of unused habitat.

Harvest estimates from: Snake River Harvest Module, June 2014, prepared by the National Marine Fisheries Service, West Coast Region, Portland, OR.

OncyT:

I understand the argument that a non-supplemented population should be the control for the experiment being discussed in the article, and I suppose I agree.

I think you might be putting a little too much faith in that there are "zero" ocean fishery impacts on those fish, and even if that's true, there are in-river fisheries that do take a toll. Granted, there are no directed ocean fisheries for springers, but when we remember that a springer is really just a Chinook that migrates upstream at a different time of year, and that it spends the majority of its adult life at sea, comingled with other salmon, we realize that a lot of what gets labeled "small" Chinook in the summer and fall fisheries may actually be next year's springers. Again, not arguing that harvest is the key with those fish. God knows, if you want to see the full extent of habitat challenges firsthand, following some Snake Chinook around will show you the whole gamut. (Keep in mind that stream nutrient levels are among those challenges, and the big reason they're lower than what they were historically is that only about 10% of the potential carcasses are being added, year after year.) That there are any of those fish still swimming is testament to how resilient salmon are.

I'm not trying to dismiss the study, its findings, or its authors. I'm neither qualified nor inclined to do so. My point was (and has been) that as long as our harvest model is set up to maximize harvest, minimum survival is exactly what we should expect.

The assumption that there is little to no ocean harvest is based on coded-wire tag information over many years, as are the in-river harvest rates, so it is not a faith-based argument. Again, in this particular case, where harvest rates are very low (4% to 17%), not many people are going to buy that the harvest model for these populations is to maximize harvest as you suggest.

Thank you FleaFlickr02 your posts were right on the mark!

I personally think nature has a LENGTHY history of doing a decent job of repairing things on it's own. It's pretty obvious the main culprit in any and all animal species decline has been the direct result of human intervention. No matter how much we blame one thing or the other whether that be the environment, predation (natural and human consumption) or habitat destruction all signs point to us humans.

One thing we also love to do is try to correct our past mistakes. We set up quota systems that don't make sense or rules governing when, where and who can fish and for what but all you get are reports of rampant violations and continuously declining numbers of fish. The major hurdle is our inability to see past dollar signs both in economical and political forms so no matter what we try to do, our best efforts to build up species numbers usually has the opposite effect. It seems to me that if we really cared about what's happening with our oceans and our species then perhaps we should stop doing EVERYTHING to the species. Specifically, harvesting by everyone.....

Now, I know everyone here is going to bash me for saying it but if we really cared about our future generations getting opportunities to harvest salmon then maybe we should have some sort of system in place to let the salmon do their thing unmolested by man. Maybe have a system where we humans can only harvest (commercial, tribal and recreational) once every other year or every two years. Something that allows nature to do what it does best....fix itself. But that'll never happen because we who "care about our oceans" cant see past the here and now.

Anyway, it's late. I don't like to think too much before bed. It'll give me wrinkles.

FleaFlickr02,
I agree with your statement that the oceans are a problem and lack of nutrients in the watersheds are a problem. ( and harvest is also a problem)

I think we can all see that without some form of nutrient enhancement in both those places the system will collapse. you can't take the trees, and the fish and the deer, and the mushrooms and the berries from the land and not replace the nutrients that they will provide when dead. the question is where is the line between pollution and fertilizer? and then we have to figure out where that line is for the ocean also...

my concern is I do not see anyone working on those questions yet.

Milt Roe,

I should have included marine smolt to adult survival as part of the habitat productivity and capacity element. Although dramatically different, the ocean is an extension of salmonid habitat.

Cncfish,

Yes, supplemental feeding in streams has been tried in limited applications - controlled flow side channels. The concept has limited applicability and is not generally feasible. I don't know of any data indicating that the subsequent adult population is increased, and I doubt that any incremental increase would be subsequently sustained by the small incremental increase in the nutrient base, if any.

FF2,

In harvest management, escapement above the goal is a harvest management failure, as is escapement below the goal. Unfortunately the level of precision some folks want from harvest management is impossible, so I think harvest management can truly only be said to be failing when escapements consistently fail to meet the goal due to over-harvest. Some runs, like PS steelhead, are not harvested to any significant degree (< 4%), and still fail to make escapement. I'd have a hard time blaming that lack of fish on over-harvest.

OncyT,

I think there are about to be some more examples where supplementation failed to increase populations. The reason is the very topic of this thread, carrying capacity is less than thought. We can supplement a spawning population all we want, but that won't increase the intrinsic carrying capacity of a given habitat unit. This is gonna' screw up a whole lotta' recovery goals that were probably more "faith based" than ecology based.

Cncfish,

Nutrient enhancement can only serve to increase fish population abundance if nutrients are the limiting factor. While more nutrients would likely help; i.e., we see native char and some trout experience a beneficial response to large pink and chum salmon escapements, there are still major ecosystem elements in PNW river systems that are severely compromised. That results in reduced productivity and carrying capacity that cannot be offset by increased nutrients alone.

Sg

Sg:

I must agree that the state of steelhead would seem to put a gaping hole in my reasoning that chronic overharvest is the ultimate limiter. I'd like to be able to argue that Puget Sound, with the most compromised habitat in the state, is an exceptional case, but sadly, other steelhead populations seem to be doing very little better. Indeed, the wild steelhead numbers we see today may be very nearly as good as their environment will allow. I do wonder if perhaps steelhead, who spend more of their lives in-river than most salmon, are more adversely affected by the relative lack of stream nutrients (which would link them to the limitations facing salmon)... but that's really not much more than a WAG.

The case for salmon, who are subject to significant harvest, is obviously quite different. It may very well be that we're at carrying capacity for the remaining habitat. I question that, however, simply because I figure the tens of thousands of salmon harvested from the ocean every year must be coming from somewhere, and while I'm no fish biologist, I understand that somewhere to be the same rivers we're arguing can't support them. I realize that just because the rivers (with hatchery supplementation) produced those salmon doesn't mean that they can sustain the full adult population returning to spawn (or that if they did all spawn, any more smolts would survive than under the established escapement goals), but I find it frustrating that, as long as we continue to harvest to the status quo, we'll never know what would happen, and we'll never know what the true limitations (or cabilities) of the habitat are. It's all too typical of how humans deal with issues like this. If it comes down to someone's livelihood (or, more accurately, someone's cash cow) or the resource they exploit, it's resource be "dammed." Every time.

The studies on the Keogh (steelhead) showed that fertilization with either fertilizers of carcasses increased smolt production. At the low marine survivals that were being seen at the time this actually resulted in the runs more than replacing themselves.

The Ford Arm studies in AK with coho showed that productivity chnaged with increasing pink escapement. At 0 escapement, the 60% HR management took 1,000 coho. At 2 kg/sq metre the same 60% HR took 5-8,000.

The fact that the supplementation may not have shown increased production only says that current productivity is being met by the management scheme in place.

Productive Capacity is not a single number. We know that coho can, if populations are high enough and instream productivity is high enough, will produce fry that smolt, fingerlings that smolt, fall smolts, and spring smolts. Lower productivity, lower escapements, and you get spring smolts which, as has been shown many times, will support some level of sustainable fishing.

Now we are getting somewhere, I have nearly given up on this board because the same old patronizing BS gets tossed out by the same high posters every time recovery comes up for conversation. Lets talk about science and data. Keogh is a great example.

the Skagit and the Snohomish have drastically decreased their carrying capacity for chum salmon the last several years. Must have been a big change in the river . I wonder what that was,

How did they decrease their carrying capacity? What measures?

Salmo g.

I agree that river structure is also a limiting factor. puget sound rivers no longer look like Oly Pen rivers or Alaska rivers. I believe they should look similar. much more large woody debris, much wider flood plains more meandering, It goes back to the death of a thousand cuts argument.

I am frustrated that here we have yet another study as to whether or not hatcheries work. when we should be studying the other 999 cuts to see if we can help some of those. I know I don't have the answer. but throwing money at getting rid of hatcheries, or supporting them is a distraction. the solution is going to take a lot of band aids, not one big crutch.

I was being a bit cynical. The measure is those rivers were open to sport fishing chums and had a lot of fish. Now they are closed and have few fish. They were netted into oblivion,roe prices went way up.