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[Matt]

It would depend entirely on how you define "wild" and "hatchery" fish.  The way I see it, "wild" fish are those fish where natural selection has occurred in every pairing in their genetic lineage to give an entirely wild genome, resulting in a very genetically-fit fish.  That said, personal definitions of what is wild and what is hatchery aren't terribly important in the grand scheme of things and probably are best left to arguments on semantics.

Now for the Genetic 101 answer... Hatcheries reduce genetic fitness of steelhead offspring as sexual selection is removed from the reproductive process.  The short explanation here is that hatcheries allow less-genetically fish fish the same chance at reproducing as more genetically-fit fish.  The process hatchery process doesn't allow for natural selection to weed out the fish that, for whatever reason, are unable to find or hold on to a mate for long enough to pass on their genes.

I'm not aware of any documented instances where hatchery programmes have benefitted wild populations, or where hatchery fish have been able to recolonize a self-sustaining population that can exist without the help of a hatchery programme.  Hatcheries do try to preserve genetic diversity by pairing one male with one female, that way if one set of genes is a dud, it only affects the offspring of a single pairing.  Hatcheries do allow fish populations to exist in numbers where habitat is unavailable to support such numbers in the wild.

[Sandman]

I think people need to exercise a little care when talking about wild vs hatchery and also about genetics, particularly when most of us are not 'experts'.

Sorry Ralph, I forgot to post my bibliography.  Absolon would be very upset with me too.  I believe the second article below is the one you posted a link to (but yours did not seem to work when I clicked to check).


Hitoshi Araki, et. al. (2009, June 10).  "Carry-over effect of captive breeding reduces reproductive fitness of wild-born descendants in the wild," Biology Letters, Retreived on February 6, 2012 from rsbl.royalsocietypublishing.org

Oregon State University (2009, June 10). "Hatchery Fish May Hurt Efforts To Sustain Wild Salmon Runs." ScienceDaily. Retrieved February 6, 2012, from http://www.sciencedaily.com­ /releases/2009/06/090610091224.htm

[RalphH]

Sorry Ralph, I forgot to post my bibliography.  

I think you mean your C-V. Go ahead I can make 30 seconds available.  

Sorry not trying insult anyone's background but just to caution about taking idle speculation as facts. How readily the findings of a few studies down south transfer to BC is hard to gauge.

believe the second article below is the one you posted a link to (but yours did not seem to work when I clicked to check).


Hitoshi Araki, et. al. (2009, June 10).  "Carry-over effect of captive breeding reduces reproductive fitness of wild-born descendants in the wild," Biology Letters, Retreived on February 6, 2012 from rsbl.royalsocietypublishing.org

the link:

 believe the second article below is the one you posted a link to (but yours did not seem to work when I clicked to check).


http://rsbl.royalsocietypublishing.org/content/5/5/621.full.pdf+html

opens a pdf ... works when I just did it. Not sure why it doesn't work for you or on this site

Last note: who defines wild by genetics? Wild is a qualitative description.

[Sandman]

I think you mean your C-V. Go ahead I can make 30 seconds available.  

No, I meant bibliography...it was the list of articles that followed.  Since I am not an "expert" myself (I am an environmental historian, not a biologist or geneticist), I get my information from other experts.  30 seconds? Sorry... I always have trouble getting my CV down to 2 pages.  

http://rsbl.royalsocietypublishing.org/content/5/5/621.full.pdf+html

opens a pdf ... works when I just did it. Not sure why it doesn't work for you or on this site

That one did work, I too am not sure while the other did not (the Science Daily one).

Last note: who defines wild by genetics? Wild is a qualitative description.

I don't know...but let me know when you find her .

[RalphH]

Based on the assumption that larger fish are killed at a higher rate, it's conceivable that angling could eventually remove the genes for large size from a population resulting in a lower average size 

there is this part and though there's been no kill on wild fish for 30 years or so kill was substantial before that. Those genes are gone. People use to think that only a % of fish were 'takers'. Catching a fish also changes it's before. It may effect reproductive efficiency. Some released fish die. I have known anglers who were quite insistent that a released fish was no longer a 'wild' fish.

[Sandy]

there is this part and though there's been no kill on wild fish for 30 years or so kill was substantial before that. Those genes are gone. People use to think that only a % of fish were 'takers'. Catching a fish also changes it's before. It may effect reproductive efficiency. Some released fish die. I have known anglers who were quite insistent that a released fish was no longer a 'wild' fish.

good points in this discussion.

Would it also be fair to say that where hatchery raised stock is released, that stock then competes with "wildstock" for both food and space? therefore it is reasonable to equate that the hatchery stock will affect the wild stock in an negative manner, especially so, if there is a point where overcrowding ( for want of a better word) takes place, the "wildstock" over time may show signs of both behavioral and physical change ie: more/less aggressive and probably a smaller size .
 Are hatchery stock more inclined to hang around than wild stock and or breed with local rainbows?
 Again through time and mating cycles this would have to make a difference to a genetic makeup. I think Gentics are directly linked to the evolution of that stock, it will adapt to change or die.

[BentRodsGuiding]

It would depend entirely on how you define "wild" and "hatchery" fish.  The way I see it, "wild" fish are those fish where natural selection has occurred in every pairing in their genetic lineage to give an entirely wild genome, resulting in a very genetically-fit fish.  That said, personal definitions of what is wild and what is hatchery aren't terribly important in the grand scheme of things and probably are best left to arguments on semantics.

Now for the Genetic 101 answer... Hatcheries reduce genetic fitness of steelhead offspring as sexual selection is removed from the reproductive process.  The short explanation here is that hatcheries allow less-genetically fish fish the same chance at reproducing as more genetically-fit fish.  The process hatchery process doesn't allow for natural selection to weed out the fish that, for whatever reason, are unable to find or hold on to a mate for long enough to pass on their genes.

I'm not aware of any documented instances where hatchery programmes have benefitted wild populations, or where hatchery fish have been able to recolonize a self-sustaining population that can exist without the help of a hatchery programme.  Hatcheries do try to preserve genetic diversity by pairing one male with one female, that way if one set of genes is a dud, it only affects the offspring of a single pairing.  Hatcheries do allow fish populations to exist in numbers where habitat is unavailable to support such numbers in the wild.




You just described most the rivers in North America

[Matt]

It would depend entirely on how you define "wild" and "hatchery" fish.  The way I see it, "wild" fish are those fish where natural selection has occurred in every pairing in their genetic lineage to give an entirely wild genome, resulting in a very genetically-fit fish.  That said, personal definitions of what is wild and what is hatchery aren't terribly important in the grand scheme of things and probably are best left to arguments on semantics.

Now for the Genetic 101 answer... Hatcheries reduce genetic fitness of steelhead offspring as sexual selection is removed from the reproductive process.  The short explanation here is that hatcheries allow less-genetically fish fish the same chance at reproducing as more genetically-fit fish.  The process hatchery process doesn't allow for natural selection to weed out the fish that, for whatever reason, are unable to find or hold on to a mate for long enough to pass on their genes.

I'm not aware of any documented instances where hatchery programmes have benefitted wild populations, or where hatchery fish have been able to recolonize a self-sustaining population that can exist without the help of a hatchery programme.  Hatcheries do try to preserve genetic diversity by pairing one male with one female, that way if one set of genes is a dud, it only affects the offspring of a single pairing.  Hatcheries do allow fish populations to exist in numbers where habitat is unavailable to support such numbers in the wild.




You just described most the rivers in North America

I didn't phrase that well.  Let me rephrase: hatcheries allow larger numbers than can be supported with available habitat in the wild.  There are two sides to that coin obviously; more fish means more availability to user groups, but at the same time more hatchery fish has a negative impact on wild fish.  I value wild fish a lot.

[Sandy]

good points in this discussion.

Would it also be fair to say that where hatchery raised stock is released, that stock then competes with "wildstock" for both food and space? therefore it is reasonable to equate that the hatchery stock will affect the wild stock in an negative manner, especially so, if there is a point where overcrowding ( for want of a better word) takes place, the "wildstock" over time may show signs of both behavioral and physical change ie: more/less aggressive and probably a smaller size .
 Are hatchery stock more inclined to hang around than wild stock and or breed with local rainbows?
 Again through time and mating cycles this would have to make a difference to a genetic makeup. I think Gentics are directly linked to the evolution of that stock, it will adapt to change or die.

oops , but here anyway

http://icesjms.oxfordjournals.org/content/56/4/459.full.pdf

edit to add:
http://fwspubs.org/doi/pdf/10.3996/092010-JFWM-032

and another
http://www.sciencedaily.com/articles/f/fish_farming.htm