SE Pa Stocked Trout Residency Surveys

[Mike]

So far a stocked trout residency survey was done on West Valley Creek near Exton. Residency was estimated to be 60% for BT and 100% for RT. Statewide, RT continue perform significantly better than BT or ST. Other waters already set up for this work are Conowingo Ck, N Br Muddy Ck - Felton section, E. Br Codorus Ck, Blymire Hollow Run.

 

[Fishidiot]

Interesting.
I would have guessed the RTs were most likely to skedaddle. I think there's something of a perception among anglers, at least in my neck of the woods, that browns are better for stocking in quality waters precisely because they will "stick" rather than migrate.

Anyway, keep us informed of the results on the other waters as they become available - will be interesting to see if the results are consistent.

 

[midnightangler]

What time intervals do these studies consider and what how much stream length do they cover? Has the PFBC ever evaluated residency beyond a year? That data would be interesting to see...

 

[troutwilleatflies]

I would love to hear the reasoning behind stocking RT & BT in the LL and no BT.

 

[Maurice]

Mike,

I am curious what you do when you are searching for stocked trout residency and you find substantial wild trout numbers in multiple age classes?

- Do you ignore them?

- Go back for summer time surveys to determine class?

Considering these residency surveys will take place in March I presume you will find wild trout along the way.

Should you find a class A population would you recommend for removal from the ATW list and discontinue stocking?

 

[pcray1231]

troutwilleat,

Because there are wild brown trout. Where wild fish are present, the PFBC tends to not stock that species. I'm not sure the official reason. One would be that the different species inhabit different niches in the stream, and stocked browns would thus more directly compete with wild browns than would bows or brookies. Another is concerns over genetic contamination of the wild stock.

 

[Mike]

Residency studies are done 6 to 20 days after the fish are stocked. Telemetry research indicates that the mass movement that concerns us occurs within a 5 day period after the fish are stocked. Sample sites are at least 300 m long directly at the stocking points, two per stocked section (sometimes 3). Sampling occurs 200 m below the stocking point and 100 m from the stocking point up with greater length covered when the bucket carriers spread the fish out. All fish stocked at each point are enumerated as they come off the truck. We rarely find that any trout have moved more than 30 m upstream and if they stay, we don't often find them more than about 150 m downstream. This work has primarily been done in streams that are 4-12 m wide although the few wider streams we have sampled have produced similar results in some cases.

 

[outsider]

Mike,

The RT number does not surprise me at all. I fish a few streams in NC PA consistantly for the past 40 years. Amazing that you can fish 50 yards upstream/downstream from stocking points and see/catch few fish in good holding water. The same residency % did not occur 30 years ago, but they did stock BT at that time.

Last year I stopped at the Little Pine (I don't fish this stream often) a few weeeks after it was stocked and looked into the water. A dense number of fish in 20 ft of stream length and very few above and below, even though the water appeared to be basically the same in that long pool. The solution?

 

[Mike]

Regarding the finding of wild trout during residency surveys, we don't ignore them, but we do not do population estimates either. As I have described in the past, but is worth mentioning again, we did a different study (statewide) of wild trout population biomass and population densities just before opening day and then repeated this work in the same sites mid-summer of the same year. Population densities and biomass were much higher in the summer, which contrasts directly with what a few have said on this message board...that so many legal wild fish, especially brook trout, are harvested on opening day that it ruins the fishing for legal size wild trout for the rest of the year (Our work indicated just the opposite....some were Class C or B in spring, Class A in summer, and legal size fish were more abundant in summer than in spring...and not because of narrower width in summer). . But I digress.

We would not do population estimates at the same time as residency work in part for the very same reason: because the estimates would be lower than summer estimates, but also because the residency work concentrates on adult fish. Nevertheless, if we find multiple year classes of wild trout in streams where they have not been recorded before, we would record the info (measure the fish) if we could do so without ruining the residency sample effectiveness or we would return at a later date to actually do a unassessed water survey, which could involve a wild trout population estimate if the population was large enough.

Typically, I run 2-man electrofishing crew for the residency work, which means the crew has its hands full just trying to sample and enumerate the stocked trout without dealing with the wild trout. For example, the crew may have to ignore the stream margins (fingerling habitat) in order to keep the adult stocked trout from avoiding the crew/electricity (running past the crew in a downstream direction). When doing an estimate of wild trout the stream margins would be electrofished.

 

[midnightangler]

We rarely find that any trout have moved more than 30 m upstream and if they stay, we don't often find them more than about 150 m downstream

Would it be a bad thing if fish spread out more than that?Congregation of stocked fish wherever they happen to be dumped would seem to reduce the likelihood that fish can holdover.

 

[Mike]

Outsider, in some waters we see 100% residency, but if I recall correctly, the average statewide is around 60-70 percent. That means that 30-40% have moved on average, if I have that number correct, but not necessarily out of the stocked section on those waters. In the worst cases, however, they have moved out. When they do move, however, they run right past our 200 meter downstream sampling starting point and keep going for some distance. We know this because we usually don't find any trout when we first start electrofishing at the 200 m downstream point. Occasionally we do. So, if fish are running, they are going past the 200 m point to parts unknown, but clearly on larger streams up to 20 m wide, based on my fishing experience, they (at least some) hold up somewhere downstream because my standard technique on opening day (when not working) was to start fishing in between stocking points and I could often pick a limit of fish off here and there without having to deal with crowds. That approach does not work nearly so well on some smaller stocked streams and now I know why. You can find the year 1 report of the stocked trout residency work on the PFBC web site if this interests you.

By the way, the RT vs BT and ST movement difference is a solid account based on a few hundred waters statewide. RT reside very well...around 90% residency. ST and BT statistically significantly less so...48-52% residency.

Side note: As some who have witnessed electrofishing can attest (if they got beyond the amazing number of fish they saw at times and paid attention to the habitat electrofished .... where the fish came from) they probably enhanced their fishing techniques, at least as far as reading the water is concerned.

 

[jbomb]

Silly question... What does "ST" stand for?

 

[Squaretail]

Brookies.

 

[afishinado]

Squaretail wrote:
Brookies.

Actually, squaretail, Squaretail. :lol:

 

[Mike]

ST = speckled trout = brook trout

 

[afishinado]

Mike wrote:
ST = speckled trout = brook trout

You ruined it for me, Mike ;-)

 

[TimMurphy]

Fishidiot wrote:
Interesting.
I would have guessed the RTs were most likely to skedaddle. I think there's something of a perception among anglers, at least in my neck of the woods, that browns are better for stocking in quality waters precisely because they will "stick" rather than migrate.

Anyway, keep us informed of the results on the other waters as they become available - will be interesting to see if the results are consistent.

Dear Fishidiot,

While I understand the thought behind the basic premise that RT should be more far ranging you need to keep in mind that "Troutus Hatcherius", AKA stocked rainbows, lack about 95% of the genetic qualities that make them trout.

By the time those puppies get dumped in a crick they are almost too stupid to know what direction to face in relation to the current. ;-)

If they are given sufficient time to relearn what should be their normal behavior they do quite well, witness that stream in Cumberland County if you need evidence. I doubt you do though.

Regards,

Tim Murphy

 

[JackM]

Narrow streams resemble a raceway. These trout are "imprinted" (rudimentary "learning") with a survival technique to stay in a group and wait for handfuls of pellets. They will stay in the group and group-feed (aggressively) when the food become available.

A few of the brutes will venture beyond the group and may or may not find competition or better habitat.

Contrast the larger water, where immediately the peabrain trout is tempted to spread out and happen upon less competition and better habitat. In any event, imprinting is quickly overcome by instinct. That it may take more than 20 days is not surpising given how long the trout has spent in the raceway environment.

An interesting twist on these experiments would be to stock a fertile stream or three and prohibit fishing, then identify travel patterns over the course of a full year. Perhaps having each plant "tagged" with a GPS transmitter. The technology is there to do this right, I would think.

 

[kbobb]

Do you take poaching into account in these surveys? We helped with pre-season stocking a mountain stream a few years ago and mentioned to the fish warden that because of poaching many of the fish would not be there on opening day and he remarked - "half these fish won't be here tomorrow night".

 

[Chaz]

If I were a betting man, I'd bet the movement of stocked trout starts as soon as they are thrown into the water. As for RT not moving, where they are native they don't move as much as many anglers think, when in streams with both cutthroats and bows, the bows and cutthroats stay in their niches and don't inter breed, it's when there are RT stocked into CT waters that you start to get the interbreeding and cuttbows impacting the gene pools of both species. This characteristic keeps the genes pure in wild trout environments.