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[CohoJake]

https://whyy.org/segments/epigenetics-may-hold-answers-to-the-survival-of-hatchery-born-salmon/?fbclid=IwAR0NZjgfXcPhmljHwg4NxtXidO4uI1Ksggl-hlWyLtPB6alu62kcOr1ln5I
A very interesting experiment being done at the Nitinat fish hatchery.

[RalphH]

Here in BC,ever since there first were large releases of hatchery smolts back in the 70s,  a lot of people have been saying that hatchery fish qualitatively behave differently than wild fish.  It's taken more than a generation for some scientists to recognize this and wonder why.

[DanL]

Very interesting link and story. Thanks

TLDR, is that they observe that tank-rearing is resulting in reduced survivability vs wild fish, and that hatchery vs wild fish can be identified through differential DNA methylation. That modification is likely resulting in differing gene expression and impact behaviour and physiology. There was a similar type study in steelhead that was discussed here a couple years ago.

They hypothesize that things like physical structure, exposure to predators etc, that more closely resemble a natural environment may result in more 'wild-like' development and therefore better survivability. They are going to compare the results of groups reared in different tank environments.

Presumably, if rearing in totally natural environments would be ideal, but impractical, then adding some 'natural' features to the tanks may have some benefit.

[TNAngler]

I've said it before but the solution is to get over that "impractical" decision.  Raise them just long enough that they can survive, then find a large number of feeder ponds around the area free of a lot of predatory fish and set them free.  You will lose some to predators but the ones that survive will learn how to survive.  Maybe feed them pellets for a couple weeks after transfer to help but after that they should be fending for themselves.

With my dad and my two brothers and myself, we were raising over a million eggs using this method and they did very well.  I am sure with volunteers/staff, the hatcheries could do very well.