Register now on PaFlyFish.com! Login
HOME FORUM BLOG PHOTOS LINKS


Sponsors

Browsing this Thread:   1 Anonymous Users



« 1 (2) 3 »


Re: Interesting Study

Joined:
2008/1/31 17:19
From Pretty much everywhere at some point, Thorndale today.
Posts: 12923
Offline
Quote:
Is it possible that there is no interbreeding due to different reproductive cycles? This would make the most sense to me. Even if they were just off by a few weeks would make all the difference. I'm not sure what triggers the spawn but maybe it is much less environmental than some think.


I didn't know that people thought it was environmental. Yeah, genetics certainly have an awful lot to do with the spawn timing. And in hatcheries they have intentionally altered this timing via selective breeding. I don't think there's any question it plays a large part in why they aren't finding crosses. Heck, with rainbows it's not even a few weeks different. Spring vs. fall!

On another point, it's also possible that they do in fact interbreed, but that the little guys don't do so well, hence the studies not finding any little guys. My gut says this isn't the case, but to be clear, there is NOTHING in these studies that would contradict this viewpoint.

And regarding tigers, do recognize that tigers are very rare. In similar sampling as these studies, it's highly likely that the researchers wouldn't have turned up ANY tigers. I don't think this completely rules out the odd case of stockies and wilds interbreeding. It just says that it's not common. Wild tigers aren't common either.

Quote:
Kinda kills the "Stocking- Over- Native argument, huh?


Not at all. That argument was never about interbreeding, at least to me. It was about competition for resources, and attracting fishing pressure of the type who are likely to harvest.

Posted on: 2013/6/21 7:43


Re: Interesting Study

Joined:
2006/11/2 8:50
Posts: 5782
Offline
Quote:

pcray1231 wrote:

I don't think this completely rules out the odd case of stockies and wilds interbreeding. It just says that it's not common.


It only shows that it was not common in this particular situation, i.e these particular waters, with these particular strains of hatchery and wild trout, and over the particular time period studied. If their methodology was correct.

That's all that it shows.

Posted on: 2013/6/21 8:15


Re: Interesting Study

Joined:
2011/3/31 12:18
From Clearfield
Posts: 2448
Offline
Yeah, but it gives us something to discuss.

Posted on: 2013/6/21 8:18
_________________
www.theavocations.blogspot.com


Re: Interesting Study

Joined:
2008/1/31 17:19
From Pretty much everywhere at some point, Thorndale today.
Posts: 12923
Offline
troutbert,

Agreed. It's not the first study of this nature, and the others I have read paint the same picture. That doesn't mean there aren't exceptions out there, as in certain streams, strains, etc. where interbreeding may be more common. I'm sure there are. But while falling well short of "proof", this looks to be the rule rather than the exception.

Fish populations are weird. It depends how narrowly you define the term "strain" or "subspecies", but it appears that there are A LOT of differentiat genetics within any one species. They started cataloging them in the west with cutties, you have the greenbacks, west slope, snake river, etc. In reality, these too are probably broad categories, and there are lots of subsets within. Bows, brookies, and browns probably have the same thing going on, though to a lesser degree with browns in North America because only 2 varieties were originally imported from Europe. But when it comes down to it, with say, brookies, you could probably find identifyable genetic differences in every little stream, even ones that are close together and tributaries of the same waterway.

I guess such a plethora of "strains" should be expected in animals with highly isolated populations.

I would still like to know how "sustainable" the hatchery strain is. So in the streams which had wilds, the hatchery fish DID reproduce, and you ended up with two distinct, isolated strains. Wild and hatchery. It seems to be logical that, if stocking were ended, one of the two strains would die out. I would predict that it's the hatchery strain which would die out, but that's merely a hypothesis. And that too could be highly dependent on the specific waters in question, specific strains in question, etc.

Fun to discuss and think about, that's for sure. But as with anything, answers will come slowly over time, and they'll answer some questions and create new questions in the process.

Posted on: 2013/6/21 8:34


Re: Interesting Study

Joined:
2006/11/2 8:50
Posts: 5782
Offline
Quote:

KeithS wrote:
Kinda kills the "Stocking- Over- Native argument, huh?


If you wanted to go fishing for wild brook trout from about now through September, which would you choose:

Streams with wild brook that are: 1) stocked over? 2) not stocked over?

If you read the posts on here by the brook trout fishermen, you see that they nearly always try to find streams that are NOT stocked. And that's true for me.

The reason is that your chances of catching wild brook trout of decent size, i.e. 8 inches or larger, are much greater on streams that are not stocked.

Posted on: 2013/6/21 8:34


Re: Interesting Study

Joined:
2010/2/18 8:57
From SW PA
Posts: 715
Offline
I'd think spawning of either group, wild or hatchery, is dependent on a) water temperature, and b) photoperiod or length of daylight. So how do those two variables compare with each group? And then how does it compare to other hatchery strains? It is interesting stuff!

Posted on: 2013/6/21 9:40
_________________
Hatches come and go of their own accord, but work will wait for you to get back.


Re: Interesting Study

Joined:
2008/1/31 17:19
From Pretty much everywhere at some point, Thorndale today.
Posts: 12923
Offline
Dave,

I'm talking out my rear end here, I'm not a fisheries biologist. Just guessing based on a more broad scientific background and a decent understanding of evolution.

But if I had to guess, I would say that your a and b are the primary forces pulling the trigger. But that genetics is what determines the trigger weight.

i.e. if a strain of stockies were bred to, say, breed earlier in the fall, then through selective breeding processes biologists have installed a "hair trigger". They're still responding to photoperiod just like the wild fish, but it happens more quickly.

But "hatchery fish" shouldn't be looked at as a single strain anymore than wild fish should be. There are multiple strains of both. For instance, Virginia's hatchery fish may be very different than the PFBC's strain, which can be different yet from the strains raised in private PA hatcheries.

Posted on: 2013/6/21 12:00


Re: Interesting Study

Joined:
2010/2/18 8:57
From SW PA
Posts: 715
Offline
Yea, that's sort of what I meant. How does the hatchery strain from VA "triggering point" compare with that of other state's strain. And then, in turn how those relate to the various wild fish they could impact.

Posted on: 2013/6/21 12:12
_________________
Hatches come and go of their own accord, but work will wait for you to get back.


Re: Interesting Study

Joined:
2012/10/24 19:22
From Da 'Berg, PA
Posts: 1243
Offline
I think trout are different to char - brown trout will spawn with Atlantic Salmon and hence the worries in Europe about stockies degrading wild runs; and bows spawn with cutts as we know.

Char are a bit different due to genetics or environment. I don't think brookies and lakers/togue interbreed much either.

In the Cape Cod study, sea run brookies from the Sandwich hatchery had 0% genetic effect on the wild stocks in the quashnet and child's rivers, that's why they stopped stocking over the wild fish.



Posted on: 2013/6/21 17:23
_________________
nowhere is so sweet, as the bosom of the vale where the bright waters meet.


Re: Interesting Study

Joined:
2010/6/26 11:19
From Along the Lehigh Above the Gap
Posts: 6822
Offline
Talked to Robert and he told me when he has a chance he will chime in.

Posted on: 2013/6/21 21:57
_________________
"Four of us wolves, running around the desert together, in Las Vegas, looking for strippers and cocaine. So tonight, I make a toast!"

http://bugflingerandfeatherlasher.blogspot.com/



Re: Interesting Study

Joined:
2013/6/25 17:12
Posts: 1
Offline
Hey all,

Shane, thanks for the invitation to view this thread and jump in. It's interesting to see this getting discussed in an angling forum! I don't have much time to respond to everything posted in response, but I thought I'd add a few quick bits:

1) The evidence for interbreeding between hatchery and wild BKT is mixed, in fact it is VERY mixed. Some disagreement between studies may be due to differences in methods. We feel very confident that our results are solid, ie. the methodology was sound. I am also equally confident that these results don't apply everywhere, but rather describe what happened in this particular situation. The point we thought was important was to underscore that it does vary, and its important to evaluate the integrity of wild stocks and not write them off as 'compromised' even if they have a long history of being stocked upon.

2) In terms of how this lack of interbreeding happened, there are lots of possibilities. All of the ones suggested here are possible and valid. There was another study that showed even different strains of wild BKT don't always interbreed as much as you would expect when they throw them in the mix together. This is something I would love to study more and is a very interesting ecological question.

3) The longevity of the hatchery strain in the system is a real interesting question. If stocking is stopped, it could be that the hatchery fish will disappear in a decade or even shorter. That has been the case in some systems, but not in others. This most certainly depends on the strain itself and its vigor in the wild, and a strain stocked in Virginia may blink out while the same strain stocked in New Hampshire may persist for decades.

I'm sure the lack of conclusive answers is frustrating here, and there is certainly some value to taking a precautionary approach to hatchery supplementation when trying to preserve wild stocks. It has value and it has risk, in my opinion. In the end it comes down to what we value, as one person suggested here. But there are many scientists out there that hold much stronger opinions on this than me, and many of them have been studying this question longer than I have. If you have any specific questions about this study I would be happy to answer them. If you have questions about some of the larger implications of hatchery vs. wild debates, I can offer my opinion on that but can't answer all the questions it raises. It's definitely fun to talk about though and I always like hearing other people's take on it.

Thanks for your interest in this work!

Posted on: 2013/6/25 18:27


Re: Interesting Study

Joined:
2010/5/1 9:10
From NE OH
Posts: 1228
Online
Thanks you for chiming in. Excellent stuff!

I wonder if Pcray will agree? Hmmm? Sorry, I have to beat up on Pcray because I can't beat up on my engineer wife that seems to think she has to verify any statement I make...even in areas I hold advanced degrees. Goobers

Posted on: 2013/6/25 19:47
_________________
"You don't need 7x. All right, 7x...now you're just being stupid. That's ridiculous. You know what else...throw away the 6x, because that's garbage too." -Hank Patterson


Re: Interesting Study

Joined:
2010/5/1 9:10
From NE OH
Posts: 1228
Online
And, my wife just looked over my shoulder, read this....and LAUGHED

Posted on: 2013/6/25 19:49
_________________
"You don't need 7x. All right, 7x...now you're just being stupid. That's ridiculous. You know what else...throw away the 6x, because that's garbage too." -Hank Patterson


Re: Interesting Study

Joined:
2008/1/31 17:19
From Pretty much everywhere at some point, Thorndale today.
Posts: 12923
Offline
haha.

FWIW, no, I don't disagree with anything rowbear said.

Not that this is a surprise. Unlike many, I actually read the study, and it's conclusions, and understand how to interpret scientific results. ;). Zing!

The one thing I learned was this:

Quote:
The evidence for interbreeding between hatchery and wild BKT is mixed, in fact it is VERY mixed.


Everything I've seen has been with similar conclusions as this study has been, so not all that mixed. That said, it's not my job to study this, but rather a side interest. Thus, I haven't done an exhaustive literature search like he probably has. Instead, I've only read those studies that searched me out! And when you troll predictable, repeatable circles, you tend to only see studies that support their position, and you only get one side of the story.

It's nice to get someone commenting who has actually studied this, officially, and has done their due diligence.

Thanks rowbear! And lack of conclusive answers is what biology is all about, lol. (As a "hard sciences" guy, I have to zing the bio guys). Too many dependent variables. Leaves you with the choice of not sufficiently isolating them, or narrowing the study so much that it only tells you .00001% of the story. I prefer the latter, which this study fits, but it results in needing a whole lot of studies just like before a clearer picture emerges.

Posted on: 2013/6/26 8:45


Re: Interesting Study

Joined:
2010/5/1 9:10
From NE OH
Posts: 1228
Online
Quote:

pcray1231 wrote:
And lack of conclusive answers is what biology is all about, lol. (As a "hard sciences" guy, I have to zing the bio guys). Too many dependent variables. Leaves you with the choice of not sufficiently isolating them, or narrowing the study so much that it only tells you .00001% of the story. I prefer the latter, which this study fits, but it results in needing a whole lot of studies just like before a clearer picture emerges.


My bride struggles with this as well. What I have always found interesting about biology is that it is the combination of all of those hard sciences. And yet, when you put them all together, variation becomes terrible unpredictable. I have always said that all of biology does fit into predictable algorithms, but we just have not had enough time to observe all of the scenarios it would take to write them. And, because of biology's inherent nature of adaptation, we probably will never be able to make all of the necessary observations to apply algorithms to all of life. The good news, as the philosophy of science teaches us, we do continually take steps towards truth, we're just never going to attain it fully.

Some of us need very predictable models to get through our days and some of us can roll with it. That's the difference between an engineer/chemist/physicist/mathematician and someone who works in the arena of life sciences. The best news, it takes all of us to make it work!

Posted on: 2013/6/26 9:05
_________________
"You don't need 7x. All right, 7x...now you're just being stupid. That's ridiculous. You know what else...throw away the 6x, because that's garbage too." -Hank Patterson



« 1 (2) 3 »



You can view topic.
You cannot start a new topic.
You cannot reply to posts.
You cannot edit your posts.
You cannot delete your posts.
You cannot add new polls.
You cannot vote in polls.
You cannot attach files to posts.
You cannot post without approval.

[Advanced Search]





Site Content
Login
Username:

Password:

Remember me



Lost Password?

Register now!
Stay Connected

twitterfeed.com facebook instagram RSS Feed

Sponsors
Polls
What kind of streams do you primarily fish?
Approved Trout Waters (Stocked Fish)
Class A Wild Trout Streams
Special Regulation Areas
Wilderness Trout Streams
No Preference All Trout Streams
120 total votes!
The poll will close at 2014/4/30 15:00
3 Comments
USGS Water Levels





Copyright 2014 by PaFlyFish.com | Privacy Policy| Provided by Kile Media Group | Design by 7dana.com