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> Salmon stocking approach
MarkDv
Posted: Apr 03, 2023 - 11:00 am


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I decided to start this thread to avoid cluttering the topic 'Halton Regional Salmon and Trout Association, Along with the ministry Salmon Penning' with the stuff not directly related to it. It appears that some other guys are interested in the discussion about the salmon stocking approach, the way salmon returns to the river/creek etc.
I start with my understanding or rather feeling because I don’t have much knowledge of the topic. I tried to look for information about it but, honestly, not very hard and would appreciate it if I could get it from here.
Firstly, I have a feeling that the position that salmon returns to the exact same river/creek where it was born a bit exaggerated, despite everybody believing in it. Again, I might be wrong and willing to accept it if I could see trustful info/research etc.
My feeling is that, generally, in real life, in biology there are no such things as immutable law, not like in math or even physics, but all things are subjected to variation and probability.
Applying this understanding to the situation we discuss (the stocking event near Bronte creek) even though that it is unlikely these stocked fish will return to this creek it is still very likely that, forcing by reproduction instinct, the fish will try to find and enter any suitable water flow for spawning. So, if it is the case, then for the purpose of the increasing fish population in LO it really doesn’t matter where to release fingerlings.
Now, let's assume these fish will never go for spawning. In this case it is, basically, a ‘Put-Grow-Take' approach, similar to that of splake stocking. While it may not be as effective in terms of increasing fish population in the waterbody it is still a very effective approach to increase angling opportunity. So I would say it’s still not a bad thing to do.
(Does anybody actually know the proportion of the wild salmons in LO compared to stocking salmons? Interesting to know…Because if most of salmon in the lake is coming from stocking not spawning then it doesn’t really matter whether the stocked fish will be able to reproduce.)
And finally if we assume that the fingerlings released directly into LO as opposed to the releasing in the upper sections of the river/creeks will have a very low survival rate then such an event in Bronte Harbor should be considered as just PR action. Is it really bad? I’m not sure. 30K of fingerlings is not a huge number actually and if it brings new adults and kids to the field - why not?
Sorry for the long post. Again, this is my feeling only, I really would like to get more info about the topic and I’m ready to accept if my thoughts are wrong.
Thank you!

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crappeeeman
Posted: Apr 03, 2023 - 11:56 am


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I don't have the studies in my pocket but they are out there just punch your question in the computer. Yes salmon return to where they were hatched. So do rainbows and brown trout. It's just like a Canada Goose pair comes back to the same area to nest every year. Now not all fish come back to where they were hatched. Lake trout do not come back, the same as a grizzly bear does not come back to it's original den. Nature is selective on how it runs its life cycle of all the species in the world. One of the good explanations you can find on salmon is on the Seattle Aquarium website. If you dive in and look at all the studies on any subject, chances are you will find the answer. Also when they tag thousands of salmon at many different areas in the open water. And those same tags then show up at the same river, this explains how the salmon can be out in the big water for years and then return to a specific river to then spawn and start the cycle all over again. I hope this helps a bit. You had a great comment. I love when people have comments or questions. Just don't ask me how to catch a salmon, not a clue. I don't fish for them.

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MarkDv
Posted: Apr 03, 2023 - 12:27 pm


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I know, I know.
But believe me there is a difference between scientific data and how it is represented in popular articles.
Consider this scenario. A hatchery releases a few thousand marked fingerlings in the creek. 3-5 years after that they started to watch returning fish in that creek and found a few dozen fish with the marker they made.
Is it correct to amaze the general public saying that ‘salmon returns exactly to the same creek’? Yes it is. Does it mean that all salmon released in this creek will returns to it? Not, really.
There are a bunch of articles like that on the net:
https://www.scientificamerican.com/article/...-navigate-back/
But the real data is quite hard to find. Partially because it is quite old data and not posted in the Internet and partially because this data shared only within a small community and also not posted.
Also, note that even in this article it is mentioned:
In contrast, hatchery salmon imprint to a much simpler environment, which may help explain why they tend to stray (return to the “wrong” stream) more frequently than wild fish do.
This is what I actually started with.

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crappeeeman
Posted: Apr 03, 2023 - 12:51 pm


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You are right that hatchery salmon return in less numbers to the original stream they were released. Some have been documented returning to the wrong stream. This is because wild salmon spend more time in the fresh water they are born in, and can recognize the original stream in the highest of percentages. I have read that article as well in scientific american. There is so much more out there. Almost all wild salmon will return to their original river, but now since we humans have screwed up our waterways etc. etc. There is no guarantee the salmon will make it to where they should lay there eggs. I am surprised sometimes that the world is still here from all the screw ups. Keep reading, the studies are out there. And again, a very interesting topic you posted.

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longfish
Posted: Apr 03, 2023 - 01:43 pm


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Also keep in mind that this is happening with other species as well and all around the lake.

Arnie

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MarkDv
Posted: Apr 03, 2023 - 01:45 pm


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Also, consider this. There are some few dozens of streams in which introduced, not native salmons are presently spawning. Does it mean that in all these tributaries salmons were stocked in the past? I don’t think so. I rather think that in many of the small tributaries salmons were introduced naturally, meaning just due to the miss of the original spawning waters.
Now, as I have some time (no job unfortunately) I dived a bit deeper to this and found a lot of interesting stuff.
For example, from here:
Geomagnetic imprinting: A unifying hypothesis of long-distance natal homing in salmon and sea turtles. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2614721/#B16
salmon imprint on the chemical cues of their natal rivers and streams has been demonstrated through experiments in which young fish were exposed to specific chemicals during a critical period of development and subsequently released to undergo their normal migrations; these artificially imprinted salmon returned as adults to breed in streams that had been scented with the same chemical
That actually means that if a hatchery would put some specific, and not readily available in the natural habitat, scent in their hatchery water, then they could navigate salmon to spawn in the tributaries they want simply release this scent into these waters.
I have no idea if it was ever attempted but I believe it is possible.

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MarkDv
Posted: Apr 03, 2023 - 01:56 pm


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crappeeeman,
QUOTE
now since we humans have screwed up our waterways etc. etc. There is no guarantee the salmon will make it to where they should lay there eggs. I am surprised sometimes that the world is still here from all the screw ups.

I totally agree with that.
But for our interests (as fishermen) it doesn't really matter if fish return to the original water or elsewhere. The only important thing is the survival rate and ability to spawn without regard to a specific tributary.
Now, I suspect that Disco or someone else could have data or suggestions that survival and reproduction rates of the fingerlings released into the upper portion of the creeks is higher than that for fish released directly to the LO.

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MarkDv
Posted: Apr 03, 2023 - 02:11 pm


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Amazing! That's exactly was made in 1976!




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Disco
Posted: Apr 03, 2023 - 03:24 pm


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First I am sorry my comments opened this can of worms.

Last I spoke with anyone with specific Lake Ontario data on wild vs hatchery fish the east end northern tribs are close to 100% wild Chinook. The west end rivers are greatly diminished because of lack of access to proper spawning habitat. That being said, I believe the last report on the credit still had somewhere around 50 to 60% wild salmon.

Salmon not only return to the river they were born in but they return to the same section of the river they were born in to spawn. There are however a small percentage of the run that wander to other rivers in the area. I have read it’s only a few percent of the total run but it enough for them to propagate other rivers. It’s mother natures safety net.

As for stocking in pens at the mouths of rivers, those fish will return to those marinas but many of those fish will never run a river.
There is data on the Steelhead for the Credit river. If memory serves me correct, stocking, only makes up a single digit percentage of the total run. The survival rate is horrible for those fish that are stocked. I have not seen any data on stocked chinook or survival rates.

In addition, from what I understand on the survival of fingerlings in general, many of them are eaten by birds and predator fish like pike that are present at the mouths of rivers constantly. Stocking fish way up river gives them a better chance of survival as they spend longer in the river, imprinting, and longer in the river growing to a larger size. The larger size helps them avoid predators, as bigger and stronger fish are more likely to make it.

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Longshank
Posted: Apr 03, 2023 - 07:27 pm


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always an interesting topic and should be explored with a very open mindset imo.....


Salmon will always spread out into various river systems....that is natures way of securing a growing or declining population.

the proof of this would be west coast wild salmon......surely they did not manage to establish strong runs in multiple rivers if all the salmon from day 1 after the last ice age started say in the Fraser River....they have to spread to ensure survival


In addition , although penning projects are a success, I agree with Disco that imprinting them further up river is the better way to go

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MarkDv
Posted: Apr 03, 2023 - 09:35 pm


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Disco, firstly, why did you call this discussion ‘can of worms’? Personally, I was always interested in this topic but never got a chance to dive deeper into it. I think we have an interesting discussion here and I, personally, am looking for information, opinions and thoughts.

Now let’s take a look at specific propositions.

Last I spoke with anyone with specific Lake Ontario data on wild vs hatchery fish the east end northern tribs are close to 100% wild Chinook.
If so, if it is 100% wild, then it really doesn’t matter where you put your stocked fish in - upstream, downstream or directly to the lake. Again, I would prefer to see the original data but from what you say here it seems like a ‘Put-Grow-Take’ approach anyway. If so (I still will try to confirm this) the Bronte Harbor event really makes full sense. Why go upstream and make it difficult if you can do it easily here as a big PR action, with a bunch of kids etc - and with the same outcome.

Salmon not only return to the river they were born in but they return to the same section of the river they were born in to spawn.
Yes, I heard it many times.
For the same river we have an olfactory explanation. If the river smells the same as it did when fish emerged from eggs and stood in the river until they went to the big water - it will return back to here. But if the smell would change, due to environmental changes (farmers activities, construction, spills etc) then I think it is unknown where salmon will head for spawning.
As for the exact same spots in the river... I think if there are only several spots in the river that are suitable for salmon spawning then inevitably they have to be ‘the exact same spots”.

Anyway, I think the main question regarding this topic is not whether salmon returns to the same tributary for spawning but rather does it mean that if salmon would not have (for any reason) opportunity to return to the same river or if salmon don’t have this ‘home’ river at all (being stocked directly into the lake) - does it really means this fish will be incapable for spawning at all.

And also: does it really mean that more fish in the given tributary is better? Let’s say in a given year there were 100 chinook in the creek. And we have X amount of smolts going to the lake later. And in the next year we had a very good run with 500 pairs going upstream in the same creek. Does it mean that we will have 5X of smolts going into the lake?
I don’t think so. There are limited suitable spots for spawning anyway and very often there is big excess in the fish numbers for that.

As for stocking in pens at the mouths of rivers, those fish will return to those marinas but many of those fish will never run a river.
Yes, that’s what I would like to confirm and see the actual research papers on that if they are available.
But remember, you just said that it is 100% wild chinook returning for spawning anyway. You also say that “There is data on the Steelhead for the Credit river. If memory serves me correct, stocking, only makes up a single digit percentage of the total run. The survival rate is horrible for those fish that are stocked.”
If I understand it correctly this data is not related to the way how stocking was performed - upstream vs downstream.

If, as I can see from literature now, the geomagnetic imprinting is playing biggest role in the returning of fishes, then I may suspect that hatching itself in the given spot is very important (because that imprinting needs some time to occur and to be at the certain period of embryo development) and as such hatching in the hatchery (away from the tributary) is already misses important things whether or not you put fingerlings in the creek or directly to the lake later.

So why then blame MNR and others for ‘unappreciated” stocking approach if it really does not make any difference?

I’ll try to continue my reading if I have the opportunity and will try to post if I find something interesting and if anyone is interested. And again I'm interested in information and opinions.

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longfish
Posted: Apr 03, 2023 - 09:38 pm


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QUOTE (MarkDv @ Apr 03, 2023 - 01:56 pm)
crappeeeman,
QUOTE
now since we humans have screwed up our waterways etc. etc. There is no guarantee the salmon will make it to where they should lay there eggs. I am surprised sometimes that the world is still here from all the screw ups.

I totally agree with that.
But for our interests (as fishermen) it doesn't really matter if fish return to the original water or elsewhere. The only important thing is the survival rate and ability to spawn without regard to a specific tributary.
Now, I suspect that Disco or someone else could have data or suggestions that survival and reproduction rates of the fingerlings released into the upper portion of the creeks is higher than that for fish released directly to the LO.

And survival rate is exactly why in Bronte they get dragged out to sea after spending a month in beside the Bronte Creek.....that way they are not released to the seagulls and other fish as readily. They stand a much better chance of reaching adult hood in larger numbers and yes I personally care not where they come back to....I care not if I catch a Port Credit released fish in front of Bronte.....I do care that they continue to exist. Take browns and I wish we had accurate data but it makes sense that if you release them on the North shore they are going to travel South without a passport......lol. For the amount released the percentage caught on the North shore will always be less than from Grimsby South. They like that warm water.

Arnie

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longfish
Posted: Apr 03, 2023 - 09:40 pm


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BTW MarkDV thanks for starting this thread and keeping it separate from the HRSTA thread.

Arnie

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MarkDv
Posted: Apr 04, 2023 - 01:11 pm


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Disco, may I ask you to give links or any tips on where I could find the data you were mentioned here? I’m struggling to find it so far.
Thanks.
QUOTE

Last I spoke with anyone with specific Lake Ontario data on wild vs hatchery fish the east end northern tribs are close to 100% wild Chinook. The west end rivers are greatly diminished because of lack of access to proper spawning habitat. That being said, I believe the last report on the credit still had somewhere around 50 to 60% wild salmon.

There is data on the Steelhead for the Credit river.


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Disco
Posted: Apr 04, 2023 - 01:24 pm


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“As for stocking in pens at the mouths of rivers, those fish will return to those marinas but many of those fish will never run a river.”
“Yes, that’s what I would like to confirm and see the actual research papers on that if they are available.
But remember, you just said that it is 100% wild chinook returning for spawning anyway.”

Just to clarify I said the east creeks are close to 100% wild.
West creeks like Bronte, Credit and 16 mile have much poorer runs. Most of this is an issue of spawning access. The MNR stocking at river mouths supplements the lake fishery only yet everyone pays into their fishing licence dollars which the river fishermen are not able to utilize the lake fish. The salmon should be pen raised up river in a suitable cold water area to allow them to imprint properly and return to spawn and bolster the low numbers in the west end. The carrying capacity of specifically the Credit is massive compared to the run numbers.
The point of pen raised in mark as IMO is to keep Chinooks for the lake fishery but prevent them from running the rivers as the MNR wants to bring back Atlantics. They stock most all of the Atlantic fry WAY up river to allow them to survive, grow and imprint and return. This is the natural cycle for all Salmonoids. Why would it be best only for Atlantics?
Answer, it’s not. The MNR has their mandate to bring back Atlantics. The Pacific species are in the way and not given the respect they should be given.

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