Fate of surplus hatchery salmon?

[kmudgn]

The question I have is why are there any "surplus" salmon. Given the state of salmon returns, viability, and the cost of hatchery fish I don't understand why they just don't release them all. It's my understanding that the Bloodstock comes from returning Salmon and not the hatchery then holding any back seems counterproductive to building up returns/stock

 

[Salmo_g]

The question I have is why are there any "surplus" salmon. Given the state of salmon returns, viability, and the cost of hatchery fish I don't understand why they just don't release them all. It's my understanding that the Bloodstock comes from returning Salmon and not the hatchery then holding any back seems counterproductive to building up returns/stock

Hopefully this isn't too long a story. First, in WA we classify salmon as either hatchery or wild. (Some wild salmon are progeny of hatchery salmon, and all hatchery salmon were at one time the progeny of wild salmon, but that's not overly relevant to this story.) Because wild salmon propagate in the natural environment where they are exposed to more sources of mortality, a much higher % of the adult population is necessary as spawning escapement to maintain the population. Because hatchery salmon are propagated in the relative security of hatchery environments, a very much smaller % of the adult population is needed as spawners to maintain the population, typically on the order of only 5 to 10% of the adult fish. Depending on the specific wild population, the % needed for spawning escapement ranges from around 30% to 100%, and with certain populations (Stillaguamish Chinook salmon) even 100% of the adults are not enough to maintain the population because of extreme habitat perterbations that have driven productivity excessively low.

So we have this management tool called "harvest rate." The harvest rate is the number and % of a salmon population that can be safely harvested without jeopardizing the size and status of the population. You can see from the above paragraph that some hatchery populations can support harvest rate as high as 95% are acceptable. In the ocean or Puget Sound where hatchery and wild salmon are mixed, a high harvest rate for the hatchery portion of the run will wipe out wild populations. In fact that is how many salmon fisheries in WA used to be managed; high harvest rates sacrificed wild populations to maximize fishing benefits and prevent excessive surpluses at the hatcheries. Then this thing called ESA (Endangered Species Act) came along and said we must maintain and recover wild populations. So harvest rates have been very significantly reduced, with the result that sometimes there are very large surpluses of salmon returning to hatcheries.

You suggest that "they" should just release all the hatchery salmon. Hatchery salmon don't work that way. They are imprinted to return to the water source of their origin, i.e., the hatchery. Hatchery salmon could be trapped, placed in tank truck, and transported to stream locations that could use more salmon, but upon release the hatchery salmon will wander around looking for their natal home, many dying before spawning in this strange place, although some will spawn. The upshot is that as a practice, this isn't cost effective, plus the ESA rules only allow so many hatchery spawners out there spawning in the natural environment.

That's the thumbnail sketch of the story.

 

[Smalma]

To expand a bit on Salmo_g information. While the hatcheries get a lot of surplus fish back to the hatchery not all hatchery fish return to the hatchery. In cases where there are alot of fish getting back to the hatchery there also will be significant numbers of hatchery origin spawning in the river with both other hatchery fish as well as wild fish. There is lots of good information on the hatchery contribution to the natural spawning populations. For example, on the Green river near Seattle the typical total hatchery returns to the river (number of fish captured at the hatchery and those spawning in the river) in recent years has been in the 10,000 to 12,000 range with an average of 25% of the return spawning in the wild. As Salmo_g mention that sort of contribution can be of concern for the managers and under ESA limitations.

Putting additional carcasses in the stream in many cases can have limited benefits for the same reason there is little nutrient benefits from the natural spawning salmon. This is especially true in Puget Sound basins like the Stillaguamish where frequent flooding flushes the carcass out of the basin before they can contribute much of their ocean derived nutrients to the freshwater ecosystem.

Curt

 

[HauntedByWaters]

I was a temp tech at Cascade Hatchery on the Skagit in Fall 2012. I would go there 2 days a week for just a short period and load fish from the trap into a refrigerated truck to become pet food. The fish were all dark by this point and I think the idea was to wait for the pond to get very full before trucking for efficiency, and so the fish seemed to have been in there a while and we’re not table quality. That truck wasn’t coming unless there was a load to make it worth it.

 

[HauntedByWaters]

Putting additional carcasses in the stream in many cases can have limited benefits for the same reason there is little nutrient benefits from the natural spawning salmon. This is especially true in Puget Sound basins like the Stillaguamish where frequent flooding flushes the carcass out of the basin before they can contribute much of their ocean derived nutrients to the freshwater ecosystem.

Curt

Why not dump them into sloughs, side channels, or small tributaries? I think in some cases this may be cheaper and closer to the road than putting them out in the main river. That’s just an idea that popped into my head.

 

[kmudgn]

Hopefully this isn't too long a story. First, in WA we classify salmon as either hatchery or wild. (Some wild salmon are progeny of hatchery salmon, and all hatchery salmon were at one time the progeny of wild salmon, but that's not overly relevant to this story.) Because wild salmon propagate in the natural environment where they are exposed to more sources of mortality, a much higher % of the adult population is necessary as spawning escapement to maintain the population. Because hatchery salmon are propagated in the relative security of hatchery environments, a very much smaller % of the adult population is needed as spawners to maintain the population, typically on the order of only 5 to 10% of the adult fish. Depending on the specific wild population, the % needed for spawning escapement ranges from around 30% to 100%, and with certain populations (Stillaguamish Chinook salmon) even 100% of the adults are not enough to maintain the population because of extreme habitat perterbations that have driven productivity excessively low.

So we have this management tool called "harvest rate." The harvest rate is the number and % of a salmon population that can be safely harvested without jeopardizing the size and status of the population. You can see from the above paragraph that some hatchery populations can support harvest rate as high as 95% are acceptable. In the ocean or Puget Sound where hatchery and wild salmon are mixed, a high harvest rate for the hatchery portion of the run will wipe out wild populations. In fact that is how many salmon fisheries in WA used to be managed; high harvest rates sacrificed wild populations to maximize fishing benefits and prevent excessive surpluses at the hatcheries. Then this thing called ESA (Endangered Species Act) came along and said we must maintain and recover wild populations. So harvest rates have been very significantly reduced, with the result that sometimes there are very large surpluses of salmon returning to hatcheries.

You suggest that "they" should just release all the hatchery salmon. Hatchery salmon don't work that way. They are imprinted to return to the water source of their origin, i.e., the hatchery. Hatchery salmon could be trapped, placed in tank truck, and transported to stream locations that could use more salmon, but upon release the hatchery salmon will wander around looking for their natal home, many dying before spawning in this strange place, although some will spawn. The upshot is that as a practice, this isn't cost effective, plus the ESA rules only allow so many hatchery spawners out there spawning in the natural environment.

That's the thumbnail sketch of the story.

Great explaination. I understand the decision process on keeping "extra" fish. However, since not 100% of the biome will be used by returning fish it seems to me that taking a chance on placing some fish into smaller (remote?) feeder streams might just help natural reproduction. Yes, I know that they are not imprinted for those waters, but who knows. It also can't hurt the local ecology if the trace elements from dead fish are deposited into local streams. That is what happened for thousands of years and the local flora/fauna all benefited.
I also understand that they are "hatchery" strain, but if they reproduce naturally in a stream does that not make progeny "wild", or at least in a few generations something that could be considered wild as they will have cycled through the inhospitable ocean and "only the strong will survive".
Of course, I have no idea what USF&W would think, but just my thought.

 

[Cabezon]

Why not dump them into sloughs, side channels, or small tributaries? I think in some cases this may be cheaper and closer to the road than putting them out in the main river. That’s just an idea that popped into my head.

Those are the habitats with some of the lowest water flows. If bacteria start decomposing the carcasses (and exploding in population) the amount of oxygen in those limited exchange areas will drop through the floor (become at least hypoxic if not anoxic). Anything that breathes with gills will die at that point.
Steve

 

[Smalma]

Why not dump them into sloughs, side channels, or small tributaries? I think in some cases this may be cheaper and closer to the road than putting them out in the main river. That’s just an idea that popped into my head.

While such an approach would place those potential nutrient sources largely out of flood harm as well potentially creating the water quality issues that Cabezon mentions the benefits to anadromous fish populations likely would not be as great as hoped. In those suggested habitats the dominate anadromous species are coho and coastal cutthroat. Currently the freshwater production of those species are being limited most years by summer/fall flows (this year being a prime example.

One of the huge problems with salmon recovery efforts (at least in Puget Sound systems) is that much of the projects/efforts are directed at easy projects (either physical or political) rather than addressing the current production bottle necks. Without a willingness to accept the pain of addressing those bottle necks our salmon stocks will not improve over time.

Curt

 

[HauntedByWaters]

Those are the habitats with some of the lowest water flows. If bacteria start decomposing the carcasses (and exploding in population) the amount of oxygen in those limited exchange areas will drop through the floor (become at least hypoxic if not anoxic). Anything that breathes with gills will die at that point.
Steve

Makes sense but aren’t these areas that fish spawn and die naturally?

 

[Matt B]

Makes sense but aren’t these areas that fish spawn and die naturally?

Yeah for that to happen I think it would take way more carcasses than an enhancement program would likely provide. Lots of us have seen side channel sloughs and beaver ponds loaded with post spawn fish carcasses, yet the gilled critters manage to survive. I think that as long as habitat connectivity is maintained, where fish and other organisms can move around within the floodplain, that populations are adapted to handle heterogeneity in DO conditions. There is lots of natural DO fluctuation in aquatic areas and the fish and bugs seem to mostly do fine.

 

[Pink Nighty]

Years ago on a memorial day weekend I went to the hatchery on the twisp to check out the Springers. They were also doing a beaver relocation project, taking problem beavers and relocating them into the upper reaches of methow and chewuch. Walked around with the wifey and ran into someone who worked there. We were talking about the fish and I asked what they did to return the carcasses to the water after spawning.

She looked at me straight in the eye and said "if we put all these fish back in the stream all the nitrogen would kill everything downstream of it." I said you're kidding, a few thousand king carcs would overload the methow? She stood firm, insisting that theres no way the river could handle that biomass. I said be careful with those beavers, they poop in the water and you dont want it to overload the system.

Even if you dumped all the fish in one spot at one time, no fucking way would that be a problem for that crick to deal with.

I left dismayed and sad for the steelhead smolts and cutts and bulls that arent eating those carcs.

 

[Paige]

The Wallace Salmon hatcher in Gold Bar has a holding pond on May Creeck that runs through the hatchery and would trap extra Coho.
I was told these are surplus for emergency needs for hatcheries that weren't making escapement needs across the state, or tribal hatcheries.
I lived on May Creek(20yrs ago) about a mile up stream and would only see Coho during floods when they could escape and cross my back lawn to go up river.
I asked a manager there once why they dont let them go up and spawn. He said there wasnt enough habitat above the hatchery to support 300 Coho.

YEAH RIGHT

 

[Gyrfalcon22]

Wonder how this is playing out in the"new" Elwha? @Cabezon How this affects not only the fish, but birds like the American dipper? Influx of spent carcasses. Invertebrates must be in a tizzy? Frenzy?
If anyone has updated Elwha news, I'd love a lazy link

 

[Paige]

Remove the dams and its almost instant improvment the following year, Elwha, Mill Creek and dozens elsewhere with similar results.

Endangered species appears in Calif. creek for the first time

It was also the first time another threatened species had made its way upstream in over...

www.sfgate.com

 

[Greg Armstrong]

Years ago on a memorial day weekend I went to the hatchery on the twisp to check out the Springers. They were also doing a beaver relocation project, taking problem beavers and relocating them into the upper reaches of methow and chewuch. Walked around with the wifey and ran into someone who worked there. We were talking about the fish and I asked what they did to return the carcasses to the water after spawning.

She looked at me straight in the eye and said "if we put all these fish back in the stream all the nitrogen would kill everything downstream of it." I said you're kidding, a few thousand king carcs would overload the methow? She stood firm, insisting that theres no way the river could handle that biomass. I said be careful with those beavers, they poop in the water and you dont want it to overload the system.

Even if you dumped all the fish in one spot at one time, no fucking way would that be a problem for that crick to deal with.

I left dismayed and sad for the steelhead smolts and cutts and bulls that arent eating those carcs.

Douglas PUD works in conjunction with that hatchery, and we watched as they placed Springer carcasses upstream in the Twisp River a few weeks ago.

They were also putting what they told me were “surplus “ males back into the river, as they had all that they needed at the hatchery.

 

[Pink Nighty]

Really glad to hear they changed their tune! My experience would have been 2014 or 2015, hopefully they've been after it for a while now! Last year during the pink run on the nooksack my wife reminded me of our experience at the hatchery, laughingly asking "what's this poor river gonna do with all this marine nitrogen? Poor fish."