Hatchery trout survival in the wild in Pa. - a few comments

[Mike]

Survival of hatchery trout in the wild: This is not meant to be an exhaustive commentary, just some thoughts/observations.....

A big difference between wild trout and hatchery trout is that the natural selection processes that immediately affect wild trout eggs, fry, and fingerlings are to a substantial extent delayed when trout are raised in a hatchery. All life stages of trout are treated against diseases; wild trout have no artificial protection in that regard. Some hatchery trout are protected against avian and other predators either through netting over raceways or indirectly through human activity during the daytime. When the eagles' nest is active at Bellefonte Hatchery, even the eagles get into the act by defending the raceways against great blue herons. Hatchery trout are regularly fed and do not have to expend much energy while foraging.

When hatchery trout are released into streams and lakes, suddenly all of the forces of nature from which they were protected are also released upon them and the rate of mortality can be high. That does not mean that some can't survive to reproduce and, in fact, they do...particularly browns and occasionally rainbows. I have never seen evidence of hatchery brookies successfully reproducing in the wild. This does not mean it doesn't occur, but I have not seen any evidence of it, nor have I heard any PFBC biologist even mention it in nearly four decades. It must not occur very often, if at all. On the other hand, fall stocked browns will immediately reproduce and do so successfully, even when stocked in streams that are actually warmwater streams. If they survived the summer in those same streams, and that is a big if, they would not reproduce because their gametes would either not develop or survive the warm summer water temps.

 

[streamerguy]

Interesting stuff.

Mike wrote:
On the other hand, fall stocked browns will immediately reproduce and do so successfully, even when stocked in streams that are actually warmwater streams.

I have noticed this as well. Even the fall spawning hatchery rainbows too(as in they spawn/attempt to right away).

Not to derail the thread too much, but a while back I exchanged a few emails with a PFBC biologist(nw part of the state) regarding the vermiculations and such on PFBC hatchery browns......specifically ones stocked in the fall. A few people think they're tigers, but most people chalk them up as weird looking browns with weird hatchery genetics or something.

After sending him a few pics, the biologist actually thought they were tigers as well. I was shocked. He said even though the PFBC doesn't purposely raise tigers it happens by accident on occasion.

Mike wrote:
will immediately reproduce and do so successfully

I'd be interested in hearing your opinions on how this affects how successful they are

 

[Mike]

We have evidence of success in that a consulting firm collected fingerlings the following late spring before the water temps became too warm for survival. We also had a fish kill in a slightly cooler stream, but one where natural reproduction was not taking place. The kill revealed fingerlings a year or two after fall stockings of adults started. The fingerlings in both cases would probably have survived in the long run were it not for warm summer water temps.

 

[geebee]

Mike wrote: I have never seen evidence of hatchery brookies successfully reproducing in the wild. This does not mean it doesn't occur, but I have not seen any evidence of it, nor have I heard any PFBC biologist even mention it in nearly four decades. It must not occur very often, if at all.

that must be a water quality or temperature issue.

all the brookies in colorado's alpine lakes were stocked either by air or backpack. those populations have been self sustaining for many years.

lest we forget, specks are chars not trout.

 

[krayfish2]

Mike wrote:
On the other hand, fall stocked browns will immediately reproduce and do so successfully, even when stocked in streams that are actually warmwater streams.

Didn't the PFBC cut the fall stocking programs back or eliminate many of them all together? If they reproduce and you wanted to establish a wild stock, that seems like a good way to get the ball rolling. Do hatchery fish being 'utilized' to spawn carry less value to the PFBC than fish being 'utilized' as freezer burned raccoon food?

 

[JackM]

Mike, can you answer this: are there any studies or practices that take hatchery stock, artificially breed them and then place the fry into a simulated environment until they can be released into a stream known to support wild trout? Survival from about 0-3 months would be predominately in the natural environment, so I would assume that those specimens most adapted to the natural environment would survive and thrive, whereas those less so adapted constitute the natural attrition.

Do biologists believe that survival of fry, where introduced as soon as liberated, would be significantly different between hatchery stock and wild reproducing cultures? Are folks right that believe that the hatchery trout gene pool is significantly diluted in favor of maladaptive offspring?

 

[jifigz]

It is pretty amazing that the eagles fend off the herons and keep that amazing supply of trout to themselves, or at least attempt to. Why is it believed that stocked Brook Trout do not naturally reproduce in PA streams?

 

[jifigz]

And please don't tell me because of the fact that there is no support or proof to back up this thought, but there has to be a reason. If Browns and Bows reproduce and they are stocked, which I fully believe they do, then why not stocked Brookies? What is it about them that makes it so hard to reproduce?

 

[Eccles]

I second what jifigz says ^ too. I find it curious that with all the stocking of brook trout that must have occurred, none have gone on to establish reproducing, 'wild' populations. Strange, no?

Has the brook trout domestication process fundamentally changed them more than how brown trout have been changed so that their fitness is even worse in the wild than browns?

 

[Eccles]

JackM wrote:
Mike, can you answer this: are there any studies or practices that take hatchery stock, artificially breed them and then place the fry into a simulated environment until they can be released into a stream known to support wild trout?

Not wishing to preempt Mike but as a partial answer to your question - yes. Sort of. They are certainly looking at things like "enriching" the rearing environment and sometimes holding stockies in natural stream reaches before wider release. All aimed at increasing post release survival of course.

 

[Mike]

Jack,
I have only read about the same hatchery modifications that Eccles reported on. We never hear about trout fry stockings in streams by agencies on the east coast most likely because they don't survive very well. As you know, we have enough trouble finding waters where fingerling stockings will be successful enough to provide a fishable population.

Some sportsmen's groups raise trout from egg to fry for stocking purposes.

I have not read any scientific studies that would answer your question directly, but I would be surprised if someone has not published a study or two that would answer your question.

 

[gfen]

krayfish2 wrote:
Didn't the PFBC cut the fall stocking programs back or eliminate many of them all together?

Resource first.

 

[Mike]

Kray,
The fall stocked streams are the same ones that are stocked in the spring. If the remnants of spring stockings can't survive the summer in good enough shape to spawn in fall, how would you expect the progeny of fall stocked adults to do so the following two to three summers before they began to spawn?

 

[krayfish2]

I was specifically referring to a stream that could support wild fish but currently has a very small wilds population or no existing wild fish. In theory, those streams that 'could' support fish 12 months out of the year could get mature fish after labor day....the fish spawn to produce the next generation. In a couple of years, PFCB might be able to remove the stream from the stocking list allowing more fish in locations where freezer fillers congregate. No? Do it to enough streams and they begin to maintain themselves.

 

[PennKev]

krayfish2 wrote:
I was specifically referring to a stream that could support wild fish but currently has a very small wilds population or no existing wild fish. In theory, those streams that 'could' support fish 12 months out of the year could get mature fish after labor day....the fish spawn to produce the next generation.

Kray,

How is that situation any different than the stocking of fingerlings into a stream that has wild trout populations limited by available habitat? How would that lead to higher wild fish numbers in th elong term? I mean, if the stream already has wild trout, it probably has as many as it can currently produce and hold. Does adding more breeding trout to the stream actually lead to long term increases in trout population or does it just briefly add slightly more prey to the food chain?

In a couple of years, PFCB might be able to remove the stream from the stocking list allowing more fish in locations where freezer fillers congregate. No? Do it to enough streams and they begin to maintain themselves.

If a large number of wild, stream-born fish are due directly to an influx of hatchery trout during the spawning season, won't the trout population just fall back to it's pre-stocking size once stocking stops? Again, I don't see how the stream will suddenly start supporting a vibrant population of wild fish if habitat remains the same as before stocking.

 

[Chaz]

Keep in mind, even though browns and rainbows spawn after being stocked in the fall that doesn't make it successful until the young mature and they spawn.
As for brookies not spawning, I've seen them at the LL going through the motions, though I've never seen a stream that had no brookies, after being fall stocked, suddenly establish a brookie population. But the genetics of the brookies stocked is so bad it's not likely that brookies from our hatchery system will ever be able to be used to re-establish a brookie population.
Hatchery stocks need to be improved if a goal of stocking is to establish wild populations in selected streams. The best and quickest way to do that is to take wild fish and get the eggs and milt from the wild stock, fertilize the eggs, and once the offspring become fingerlings, put them in the stream you want to establish a population in. And only then do you do it if the tribs don't have established populations or the wild stock came from those tribs.
Anytime you want to establish a new population of trout the best way is to use wild fish to stock the stream or plant fingerlings from wild stock that hopefully came from the same watershed. The hatchery program could have an allocation for this.

 

[troutbert]

krayfish2 wrote:
I was specifically referring to a stream that could support wild fish but currently has a very small wilds population or no existing wild fish. In theory, those streams that 'could' support fish 12 months out of the year could get mature fish after labor day....the fish spawn to produce the next generation. In a couple of years, PFCB might be able to remove the stream from the stocking list allowing more fish in locations where freezer fillers congregate. No? Do it to enough streams and they begin to maintain themselves.

Does anyone know of a stream that has no wild trout that they think has all the necessary conditions for supporting wild trout, but simply needs trout to be introduced?

I don't know of any such streams. It's possible that a few might exist, but it's probably an extremely rare thing.

If such a stream was found, the sensible thing would be a one time introduction of wild strain trout. Not put hatchery strain trout in there.

 

[troutbert]

geebee wrote:

Mike wrote: I have never seen evidence of hatchery brookies successfully reproducing in the wild. This does not mean it doesn't occur, but I have not seen any evidence of it, nor have I heard any PFBC biologist even mention it in nearly four decades. It must not occur very often, if at all.

that must be a water quality or temperature issue.

all the brookies in colorado's alpine lakes were stocked either by air or backpack. those populations have been self sustaining for many years.

It seems more likely that the difference is in the strain of the trout.

You cannot assume that the PFBC hatchery strain brook trout and the strain of brook trout stocked in CO are similar. They are the same species.

But there are great differences within species, even in the wild, but when people use genetic selection, they create very large differences, and pretty quickly.

A chihuahua and a Great Dane are the same species. The enormous differences were created by selective breeding.

Also, in PA hatchery brook trout are frequently stocked over wild brook trout. So the water quality and temperature are suitable for brook trout. So, if it's true that these hatchery brook trout are not reproducing, it's because of genetic limitations.

IF it's true. I once saw a hatchery brook trout paired up on a redd with a native brook trout.

Many people on this thread are apparently thinking of hatchery trout spawning as a GOOD thing. But if hatchery brook trout are spawning, that's a BAD thing. Because brook trout are the native salmonid in our streams. Alteration of the gene pool of native fish by inter-mixing with domesticated strains is a bad idea.

 

[krayfish2]

Hold the phone troutbert. Don't lump me in with others. I'm taking a bit of what Mike is saying and mixing in a touch of what OldLefty posted in a similar thread.

A. If hatchery fish are = to wild fish in genes..... and
B. Fall stocking = fish immediately spawning

Why not stock adults in the fall and let them 'do their thing'?? Wouldn't that end up helping bolster the wild / stream raised fish population? That is me playing devil’s advocate.

I believe that hatchery fish are close in genes but most won't survive a few weeks due to angling pressure, predation or lack of survival skills. Stocking over wild fish due to angling demand may be needed but the fish stocked should be sterile so they don't damage the existing populations gene pool. I don't necessarily like the idea but the license paying public pressure may require it in some populated or high use areas.

Take a look at the markings and fish shape of fish from Penns, Letort, Juniata, Big Spring and Delaware. Compare those to what the PFBC is putting in the creeks. Did they selectively breed out the yellow and red spots? Most of what they put in are marked like a chain link fence of black blobs...not even dots. They might be trout but something's quite different. Compare a 2 year old hatchery fish stocked by PFBC to a 2 year old fish tossed in the Beaverkill by NYDEC. Body type, spot pattern, fins, etc. are very different. A fish from NY could be mistaken as wild after a month or two in the river. Not the case with the strangely spotted, nubby finned things PFBC turns out. Look at a farm raised hog and a feral hog. They are basically the same genes but are quite different in appearance.

On more than one occasion, I've suggested that the PFBC pull eggs and milt from existing wild populations to help develop our own stock from wild fish to help jumpstart a reclaimed stream or reestablish a population where wild fish once lived. Could apply to browns or brook trout. Sample a dozen fish from Spring / Logan branch....Valley.....Penns.......Big Spring.......Little J......Letort......Delaware and others. Raise them in raceways with cover (as Jack suggested) and little human contact. Plant those 4"-5" fish..... or ..... raise them to spawning age and breed once. You might go from 2500 fish with fresh / superior genes to 25,000 due to hatchery having much higher success rate of hatching out. Plant those fish in a project water. For lack of argument, I'll pick the Yough, below Raystown or the Lehigh (if they can get better releases). You've now introduced what I'd consider a superior strain of fish. That's the kind of stocked fish you'd like to have reproducing. Carefully manage the frequency and waters you pull from as to help minimize inpact on existing populations. Also, the PFBC should give serious consideration to identifying known spawning areas and they should be closed to any type of use from October 15 - March 31. PA has enough streams (even marginal streams with thermal refuges) that can / will support their own wild populations. How about managing in that direction instead of focusing on and dumping finless trout that are shaped like sunfish in for the opening day crowds?
Just a thought.

 

[PennKev]

Well that's assuming that breeding a super wild strain for your stocking plan would actually create a strain that has an advantage over the wild trout already existing in the stream receiving the stockings.

Face it, a stream with limited wild trout has a limited trout population for a reason(s). Any wild trout that are present may very well be the most suitable for that waterway already. Even if you bred a super wild strain of fish for the purpose of stocking, why do you think it would be more successful than the existing wild fish. Also in you examples of where you are selecting fish from, you are citing some of the best trout habitat in the state in terms of producing numbers and average size of trout. These fish are not necessarily better wild fish, they were just lucky enough to live in good habitat.

The way I look at it is this: A stream either has a self sustaining wild trout population or it doesn't. If the stream has wild trout but the numbers are limited, habitat is probably the issue, not the strain of trout present in the system. If your goal is just to spawn more fish in the stream, spawning habitat is probably more important than how many fish are using the available habitat. Improve habitat and the fish will take care of themselves.

About the only time I think there would be a need to stocking a wild strain would be the tailwaters you mentioned. In these cases you are looking for either trout that will establish a strong breeding population of wild trout, or trout that will survive well in the wild once stocked, or both.

As for streams that do not have wild fish, it is probably again a problem with habitat and I don't think wild strain fish is the answer. How do you breed a trout to overcome warm temps, siltation, widened channels etc. Many of our streams face one or several such problems and until they are fixed no trout will create a viable population there.