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Re: On the Subject of Stockie Reproduction - Fingerlings

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2011/5/6 17:55
From Harrisburg
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My opinion is similar- that fingerlings can and do successfully reproduce, and some of those do successfully begin multi-generational lines. I was looking for an explanation to this apparent disparity between fish of the same genetics. It has been rumored that some strains of fingerlings are indeed more wild than others (in other states, at the least), which would help answer the questions that arise.

However, if fingerling populations are not actually different strains AND they do manage a population hold better than adult trout, then we can closer conclude that more detrimental variables lie in their time in the hatchery rather than their biology. One of the biggest differences to my eyes would be that fingerlings are often released in the fall and very early spring.

As Maurice chimed- more time in the stream, the better chance of success for both survival and reproduction.

Posted on: 2013/7/5 14:28


Re: On the Subject of Stockie Reproduction - Fingerlings

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2008/1/31 17:19
From Pretty much everywhere at some point, Thorndale today.
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Obviously this is highly complex, and the real answer is probably "all of the above", as there are a million different situations. Different strains over time, competing/interbreeding with different wild strains, etc.

But as for nature vs. nurture, I used to be in the nurture camp, but have changed my tune after reading a lot about this stuff. When hatcheries struggle to raise wild strains from eggs, that's not environment and conditioning. Same goes with the success of the stockies, there's a number of reports which show them not interbreeding and not surviving for more than a few generations. And reports of success with stocking wild strian fish.

Caveat being that every single study is narrow in focus. This particular stocked strain paired with this particular wild strain in this particular stream. There's too many possible combinations, and not nearly enough studies. So you never say never. And I don't doubt that some states/hatcheries use more viable fish than others, or that some wild strains may be more likely to interbreed with them.

But my "general"/"most of the time" position, until proven otherwise, is that the BIOLOGY of stockies has changed considerably enough to significantly handicap any population they may seed, and significantly reduce interbreeding with existing wild populations. Thus, in the total absence of other fish, yeah, perhaps they could seed a new population. But when conditions allow, wild trout will typically be there. And if left to their own devices, those wild populations will outcompete stocked strains of the same species. It would require a long time of isolation for the stocked strains to get back to enough viability to outcompete wild strains.

So, case of the Little J. Did fingerlings reproduce? Yep, I'm sure some did. Was the current population seeded by them? No, I have grave doubts that there's much influence on today's population from the stockies. Wild populations always existed there, and this strain likely didn't interbreed with stockies much, and outcompeted the stockies. Hence, stop the stocking, and stocked strains die out, wild strains thrive.

Same goes for the Letort. There were some wild fish all along. When conditions became ripe for trout, it was the wild populations which took off. On the lower end, there may well be a different strain than the upper end. It could be that stocked genetics took hold here, but I find it more likely that it's a different wild strain which colonized it.

Posted on: 2013/7/5 14:49


Re: On the Subject of Stockie Reproduction - Fingerlings

Joined:
2011/5/6 17:55
From Harrisburg
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I, like you, find the subject fascinating and wish there was more literature on it (and, compared to many fields of biology, it's near academic!)

Definitely have to agree that it's the wilds that must be given the vast benefit of the doubt for repopulation credit, unless proven otherwise. The articles I was reading, however, were giving a different idea that seemed counter to the established wisdom.

Posted on: 2013/7/5 16:42


Re: On the Subject of Stockie Reproduction - Fingerlings

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2006/11/2 8:50
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It's really not complicated.

Which strain of trout should you use when your goal is establishing a new population of trout:

1) Wild strain trout?

2) Hatchery strain trout?

It's kind of like the question of what tool to use for driving a nail?

1) Hammer?

2) Pliers?

It might be possible drive a nail with a pliers. But... well, you know.

Use the appropriate tool for the job.

Posted on: 2013/7/5 17:20


Re: On the Subject of Stockie Reproduction - Fingerlings

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2011/5/6 17:55
From Harrisburg
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Absolutely! I haven't yet found any information that PA actually uses hammers for that purpose, however. My impression right now is a one-strain-fits-all attitude regarding state fish in hatcheries

Posted on: 2013/7/6 10:09


Re: On the Subject of Stockie Reproduction - Fingerlings
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2006/9/9 9:29
From Monessen, PA
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The natural environment will "re-select," if you want to call it that, for adaptable blood-lines.

Posted on: 2013/7/6 11:40
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Peace, Tony



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