NY study on effects of stocking browns in water w/ brookies

k-bob

k-bob

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http://www.glsc.usgs.gov/publications/2013/1662
 
Interesting article.
 
well researched imho.
 
That was interesting, but I don't get them saying "causes of the decline of Brook Trout in their native range are not clear"? Not clear??
 
"Intensive annual stocking of Brown Trout could eliminate resident Brook Trout in less than a decade."
 
I really don't get it. "The abstract of the report states: Intensive annual stocking of Brown Trout could eliminate resident Brook Trout in less than a decade. Ecological differences, harvest behavior, and other habitat changes can exacerbate Brook Trout losses. Custom stocking scenarios with Brown Trout introductions at relatively low proportions of resident Brook Trout populations may be able to sustain healthy populations of both species within their present range." Note the key word "may" in the last sentence. When I was still working we called these 'weasel' words.

How can the premise of this study be so. There are many other studies showing not only the opposite but give the reasons why: Brook trout are 3 times more likely to be harvested than brown trout in waters where the two species are living in sympatry in similar numbers (Cooper); brown trout (because they tend to be a little bigger than brook trout) can displace brook trout from critical stream positions (Fausch & White); brown trout can carry diseases (Saprolegnia) to which they are pretty much immune, but brook trout and other salmonids are very susceptible (DeWald & Wilzbach); and many others.

I fish for brown trout lot and have a lot of respect for them. Brown trout, like brook trout, are an excellent sport fish. I'm an immigrant too and my ancestors came from the same places. Their introduction could have been much worse (think snakeheads and carp). Catching big browns in the Little J and Spring Creek is a fine experience that I enjoy immensely. But they have taken over and dominate all the waters where brook trout once averaged 9 inches; frequently reached a foot; and occasionally 20 inches - the big freestones and limestone stream of PA. "Although we have not lost the brook trout as a species, we have lost a lot." (Charles Gowan).

This is just another attempt to justify the widespread policy of stocking brown trout over brook trout and other native salmonids.
 
"New York State contains a large portion of the Brook Trout's native range, where both species are maintained by stocking and other management actions."

The brook trout populations are "maintained" by stocking? Really?
 
KenU: "This is just another attempt to justify the widespread policy of stocking brown trout over brook trout and other native salmonids."

uh sure, that's what USGS scientists are doing
 
The statement: "Custom stocking scenarios with Brown Trout introductions at relatively low proportions of resident Brook Trout populations may be able to sustain healthy populations of both species within their present range" was why I said that the report could be used to justify the practice of stocking brown trout over brook trout populations.

I can't imagine how that conclusion could be reached considering the results that are outlined in the rest of the abstract.
 
apparently those are the results: the worst brown trout stocking practices could severely impact wild brookies, but the best brown trout stocking practices may be consistent with brookie conservation. that's how I read them anyhow. don't recall all details but stocking that is too frequent, or intense, or involves too much of a stream length, and attracts much harvest increases impact. struck me as a careful study but some of the methods were over my head.

I had a way to read it online, but won't try to repeat a long study. if you want the full study a university library near you may uh stock it :)
 
KenU wrote:
The statement: "Custom stocking scenarios with Brown Trout introductions at relatively low proportions of resident Brook Trout populations may be able to sustain healthy populations of both species within their present range"

As I pointed out in another post, they also said this, earlier in the abstract:

"New York State contains a large portion of the Brook Trout's native range, where both species are maintained by stocking and other management actions."

In both of these statements they are saying that brook trout and brown trout populations are "sustained/maintained" by stocking.

Does anyone reading this believe that they are? If stocking ended, would brook trout and brown trout populations disappear?

 
better to read this study than make too much of one ambiguous abstract sentence? You probably can find the studying actually read it if you want to
 
Here's a news release put out by the USGS about the same study:

http://www.usgs.gov/newsroom/article.asp?ID=3754&from=rss

"There is great potential for brown trout stocking to reduce native brook trout populations," said James McKenna, USGS scientist and lead author of the study. "But brown trout aren’t necessarily causing the current brook trout declines, and managers may be able to develop sustainable scenarios to support both fisheries."

 
right, like the article, the press release notes the problem with repeated disproportionate stocking.
 
Troutbert has it right. Stocking hatchery-raised trout in order to maintain a population is factitious. Stocked trout have been adapted to hatchery life for many generations now and have lost many of the characteristics needed for survival in the wild. Wildness is the first trait to be lost when any animal is brought into captivity. This is especially true of hatchery-raised (i.e., domesticated) brook trout. They are dumb as a box of rocks.
 
This article discusses the same study.

http://www.outdoornews.com/January-2014/Study-Wild-brook-trout-do-suffer-from-stocking/

Note the title: "Wild-brook-trout-do-suffer-from-stocking"

This article was posted on paflyfish before and discussed extensively. I did a search but couldn't find it. I haven't had much luck with search tool on here.
 
The paper is interesting but I'm not sure I buy some of their assumptions. Leaving aside the outputs from their neural network model the results they generate for the impact of stocked brown trout on top of brook trout are only as good as the assumptions they use to drive the model.

For example they cite two articles to support the fact that brookies are easier to catch than browns. One leads directly back to the NY "Trout" webpage (http://www.dec.ny.gov/animals/7016.html) which is a useless as supporting evidence (I'm surprised they got away with using this as a reference) and the other to Cooper's 1952 study on brook trout versus brown trout harvest rates. That may well be a good study (I've only read the abstract at the moment) but I'd like see how relevant it is to NY 60 years later.
KenU rightly points out the detrimental effects on Brook trout domestication but the same is true for brown trout. Are hatchery brown trout really good competitors of wild brook trout? And do they get caught significantly less than wild brook trout - they must be equally as dumb as the box of rocks hatchery brook trout after all. It could also be argued that they are a more prized target for the harvest crowd being bigger and more apparent.

In connection they authors also ignore modern C&R practice (unlikely to be a significant factor back in the 1950s). I wonder if wild brook trout would be harvested at 3 times the rate of browns given their possible smaller average size, C&R and increasing education of anglers to the parlous state of the species.

In general brown trout can impact wild brookies and KenU is right in some of the ways that is played out but in the wild these are often relatively subtle, condition dependent interactions and have to include other factors such as habitat change (increasing mean water temps for e.g.).

McKenna et al. seem to be taking a very coarse grind to look at what is inevitably a finely milled topic.

Anyway that's enough from me.
 
TB: right, stocking can impact wild brookies, the effect differs with stocking frequency, intensity, % of stream miles stocked, # anglers.

so how many of PA's brookie streams are stocked?: EBTJV: "Of the 5,044.3 miles of stream that support some level of brook trout reproduction, a total of 299 sections and 1,268.65 miles are also stocked with hatchery trout." That's a quarter - even if you assume that 100% of the length of those streams is stocked.

So less than a quarter of PA brookie stream miles are stocked. And stocking can be managed to conserve wild brookie populations, if not every fish or all of the larger ones. In fact, many of the PA streams that now have good wild brookies were stocked in the past - look at old records. How could that be if stocking were so damaging to native brookie populations?

And even when you guys do get PA trout stocking and Federal taxes changed to your liking, I still won't pursue the 20" natives that reappear in the Loyalsock -- I'll be afraid of the mountain lions! :)


 
k-bob wrote:

In fact, many of the PA streams that now have good wild brookies were stocked in the past - look at old records. How could that be if stocking were so damaging to native brookie populations?


Mr. Miko of the PFBC stated recently that the brookie populations on those streams improved when stocking ended. And other PFBC biologists stated the same thing at the trout management seminar they held in the mid 1990s and they had data from many years of stream surveys to support it. And what you actually see out on the streams also supports it.

I'm not sure that the NY study actually contradicts this. Their language is quite vague.

But if they are contradicting this, go with the PFBC biologists. They have solid data on this.
 
k-bob wrote:

I still won't pursue the 20" natives that reappear in the Loyalsock

The stocked portions of the Loyalsock are not even on the reproduction list. There is no chance whatever that stocking will end there.

Neither PATU or TU national has ever advocated ending stocking on the Loyalsock.
 
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