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Re: A day in the early March life of an AFM

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2006/9/13 10:18
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Another point to consider is that stocked brown trout are also immature when stocked and because they mature later in life than either rainbows or brook trout. They would have hard time successfully spawning in Pa. under current conditions. Stocked browns would have to survive 1.5 to 2.5 years as holdovers before they can spawn. We know they try to spawn because we see them cutting redds.
The big question is where’s the proof they are successful? Successful defined as having offspring that reproduce.
OF all trout eggs spawned, estimates vary on survival, but as a general rule 1 in 1000 eggs survive to maturity.
The answer to Maurice's questions are never and never.

Posted on: 2010/3/13 13:39
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Re: A day in the early March life of an AFM
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Quote:

Chaz wrote:
Another point to consider is that stocked brown trout are also immature when stocked and because they mature later in life than either rainbows or brook trout. They would have hard time successfully spawning in Pa. under current conditions. Stocked browns would have to survive 1.5 to 2.5 years as holdovers before they can spawn. We know they try to spawn because we see them cutting redds.
The big question is where’s the proof they are successful? Successful defined as having offspring that reproduce.
OF all trout eggs spawned, estimates vary on survival, but as a general rule 1 in 1000 eggs survive to maturity.


Well this is just flat out WRONG. While most brown trout are stocked at age 18 mos, they mature and egg development occurs at age two in approximately 70% according to a Wisconsin study , the fall after they are stocked, or rather when stocked if stocked in the fall. The abstract states that 100% are sexually mature at age 3.

Myth Busted.

I believe it is true that they are "not as successful" but they are successful in some cases and drainages. The notion that the brown trout populations in PA are direct and unmixed decendents of thos 120,000 eggs from over 100 years ago is laughable. If that were true ONLY the drainages where they first were stocked would support the wild strains. Unless Suitable numbers of spawning pairs were transplanted....or unless offspring were cultured and released into the wild and further propogated the species.

If stocked brown trout are so sexually insignificant, whats the problem with stocking over wild trout? Other than incidental harvest of wild fish?
I always though there was fear of diluting the gene pool. You can't have it both ways.....They don't reproduce.....they reproduce with wild trout. Which is it?

The fact is that the limiting factor to trout reproduction in the wild AND trout populations in the wild is Habitat for both survival of all age classes and spawning habitat. Some drainages have portions of these traits but not both in the same areas. These mixed "wild/stocked" trout watersheds will never be ideal trout breeding grounds like the famous wild brown trout waters or they would have been in spite of the stocking. It is also true that while stocking does encourage harvest that cropping of adult wild trout does occur. This is an undesireable side affect of stocking in watersheds with wild trout but the alternative would be a population of wild fish nearly undetectable by most average anglers, thus rendering the fishery useless except to a limited group of anglers.

Posted on: 2010/3/13 14:03
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Re: A day in the early March life of an AFM
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Interesting.
For what it's worth, I'm in the "don't know" camp with regards to much of this. It would be interesting to hear Mike's or another fisheries biologist or harchery employee's take on RT egg production. As for Mo's question on eggs seen extruding from rainbows caught in PA: I can't recall ever seeing this myself. I am, however, familiar with three streams that have wild rainbows that are well known: these being Spruce Cr, Falling Springs, and Big Spring Cr. I have personally seen RTs spawning in the Sept/Oct time period on Spruce and Big Sp but NEVER on Falling Sp. The Spruce fish would likely be hatchery fish that moved out of club waters into the Harvey stretch where I saw them spawning in Sept. Big Spring is a tougher call. I saw RT's spawning there in Sept 2009 and while these were large fish, some were in the 15" range making it highly unlikely they would be hatchery escapees (the hatchery closed in Sept 2001). Perhaps, in the case of Big Spring, there are some RT's - born in the wild - that continue to spawn in the fall (?) Of course, an exception doesn't disprove a rule and I agree that wild RTs in PA continue to be spring spawners in long standing wild populations uncontaminated by hatchery fish, such as Falling Springs.

Posted on: 2010/3/13 14:30


Re: A day in the early March life of an AFM

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Thanks for the schooling Mo, I'd be interested to her your take on the MC watershed. I also am in the "don't know" category, although I have come up with some abstract thinking of my own.

I prefer the more analitical theories as apposed to the typical "nuh uh and uh huh" back and forth arguments. It gets redundant, nice when some of the posts have some substance to back up a claim.

Posted on: 2010/3/13 20:05
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Re: A day in the early March life of an AFM

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PFBC rainbows are fall spawners. The lighthouse is used only to make a select portion of the PFBC brood ready for egg and sperm stripping earlier than the fall (meaning in summer) by changing the photoperiod. In that way the young produced through photoperiod manipulation spend a few months more in the hatcheries than the progeny of traditionally spawned adults (not exposed to lighthouse photoperiod manipulation) and are, therefore, larger when stocked in two springs later, helping the PFBC to achieve the 11 inch average length objective for adult stocked trout.

Posted on: 2010/3/13 22:19


Re: A day in the early March life of an AFM
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Quote:

Mike wrote:
PFBC rainbows are fall spawners. The lighthouse is used only to make a select portion of the PFBC brood ready for egg and sperm stripping earlier than the fall (meaning in summer) by changing the photoperiod. In that way the young produced through photoperiod manipulation spend a few months more in the hatcheries than the progeny of traditionally spawned adults (not exposed to lighthouse photoperiod manipulation) and are, therefore, larger when stocked in two springs later, helping the PFBC to achieve the 11 inch average length objective for adult stocked trout.


Thanks for responding Mike....Interesting. I am curious how the RT stock became fall spawners in the first place.

It is true that the bulk of the RT stocked in PA are less than two full years old and therefor sexually immature. But how many are held over until their second fall when they would/could be producing eggs?

In other words, for instance, in a spring stocking such as the one at Muddy Creek this year, there were very good sized rainbows 13-15". Are these fish less than two years old?

Or rather, is there a significant number of RT held until two years old for fall stockings when they could potentially spawn in the wild?

In your story about the Golden RT, do you suppose these were 2+ yer old fish?

The crux of my querry is to shed some light on the sexual maturity of state stocked RT and how it relates to the lack of RT wild trout waters in the state.

Posted on: 2010/3/14 10:24
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Don't hit me with them negative waves so early in the morning. Think the bridge will be there and it will be there. It's a mother, beautiful bridge, and it's gonna be there. Ok?


Re: A day in the early March life of an AFM

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Quote:

Maurice wrote:
Quote:

Mike wrote:
PFBC rainbows are fall spawners. The lighthouse is used only to make a select portion of the PFBC brood ready for egg and sperm stripping earlier than the fall (meaning in summer) by changing the photoperiod. In that way the young produced through photoperiod manipulation spend a few months more in the hatcheries than the progeny of traditionally spawned adults (not exposed to lighthouse photoperiod manipulation) and are, therefore, larger when stocked in two springs later, helping the PFBC to achieve the 11 inch average length objective for adult stocked trout.


Thanks for responding Mike....Interesting. I am curious how the RT stock became fall spawners in the first place.



Selective breeding.

Just as selective breeding is used in agriculture and other domesticated animals to get desired traits, selective breeding is also used with trout, for aquaculture.

Posted on: 2010/3/14 11:01


Re: A day in the early March life of an AFM
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Mike, if you know, please also address whether the selective breeding suggested by troutbert results in broods of only fall-spawning rainbows. Does your example of the Golden and other rainbows in the stream trying to mate a wild exception or is the phenomenon of fall-spawners attempting to do so in the Spring fairly common?

Posted on: 2010/3/14 11:07
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Re: A day in the early March life of an AFM

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Below are some quotes from the PFBC website. Note that the genetic heritage of the golden rainbows is different than that of the other rainbows. They are raised as a seperate line from regular rainbows.

The regular PFBC rainbows are fall spawning in the hatcheries. But are the golden rainbows fall or spring spawning in the hatcheries? I don't know, but maybe Mike knows.

http://www.fish.state.pa.us/pafish/fishhtms/chap16.htm

--------------------------------------------------------
Rainbows have been intensively cultured in fish hatcheries. Strains have been developed that are of various colors, are tolerant of warm water, grow rapidly, resist disease and spawn at times different from the rainbow’s natural spawning time.

The golden rainbow trout is a gold-orange rainbow trout raised under artificial fish culture conditions and stocked as a novelty for angling sport. The golden rainbow was developed from one fish, a single female trout with a genetic mutation that gave her a mixed golden and normal rainbow trout coloration. She was found in the West Virginia hatchery system in 1954. Through selective breeding with regularly marked rainbow trout, an all-gold, golden rainbow trout was developed. In 1963, this fish strain was popularized as the “West Virginia Centennial Golden Trout.” Pennsylvania and other states hybridized the pure strain of West Virginia golden trout with normal rainbows and produced palomino trout, which were true genetic palominos. Palomino trout were first stocked in Pennsylvania in 1967. Since then, the genetic strain in Pennsylvania has weakened, but in recent years the hybrid was selectively bred back closer to the stronger, better-colored golden rainbow trout. Although palominos were stocked as both average-sized and large trout, today’s golden rainbow is raised only to trophy size for anglers and stocked throughout the state.
------------------------------------------------------

Posted on: 2010/3/14 12:05



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