Question regarding Wild Brook Trout Enhancement Program

[JackM]

He's referencing mine, I believe, and he is equally incorrect. Most wild trout enthusiasts simply believe that over harvest occurs frequently under statewide regs. I suggested they believe it is because they think that allowing 5 fish a day would result in my hyperbolic situation. I did not use my hyperbole to set up a false argument of my opponent that I could more easily tear down. Hence my distinction with strawman fallacy, which was supposed to be tongue-in-cheek in my response to TB. But I vow to let the conversation drift back to the real issue, other than how I characterize my or anyone else's argumentation.

 

[pcray1231]

nah, I was referring to this from TB:

This is a strawman:

"It is a significant fallacy in many wild trout enthusiasts thinking that they surmise that every license holder will visit any given stream and harvest their daily limit on a daily basis."

The intro makes it descriptive of the fallacy. But, if rather than ascribe it to wild trout enthusiasts, you held this belief yourself, I would place it as:

Appeal to the extreme, and approaching reductio ad absurdum. You could also include sweeping generalization. If you asked me to prove you wrong, it'd be an appeal to ignorance.

I'm reasonably well versed on logical fallacies.

My interpretation of eccles proposed experiment was that he was building a strawman. Eccles agreed it sounded that way, and further described his position. I accepted. But strawman was the correct term.

 

[LeTortAngler2]

Chaz Posted on: Today 9:19
"I would add that removing browns from brook trout streams would also do the trick."
Respectively, I think this could be done on certain streams with current high populations of natives throughout its length, but to remove all the browns from all the Native Brookie streams probably would end up being temporary for the majority. (linn run westmoreland cty comes to mind of a local chapter currently trying to eradicate the browns ). Without the more hardy and pollution resilient browns, some streams would not even be worth fishing imo, while all the Brookies would be only in the headwaters condensed to their suitable habitat and likely drawing more pressure to headwaters. The same goes for the recent talk over removing rainbows out of BigS while Brookie and Rainbow populations are on the rise.? I do not show favoritism to any of PAs 3 wild trout species and respect what Enviroment that they have chose to thrive and am thankful for the sport they provide. Browns and Brooks have coexisted for years and will likely continue doing so for a long time.

PennKev- "Our waterways have been altered to the point where browns are simply a better fit for them and can reside in a larger and more diverse variety of habitats found in this state. And for that matter, I think a lot of it has to do with water temps. I think our water temps are no longer consistently cool enough to allow brookies to take advantage of more fertile waterways the way browns do."
^^ Agreed

 

[troutbert]

pcray1231 wrote:
nah, I was referring to this from TB:

This is a strawman:

"It is a significant fallacy in many wild trout enthusiasts thinking that they surmise that every license holder will visit any given stream and harvest their daily limit on a daily basis."

The intro makes it descriptive of the fallacy. But, if rather than ascribe it to wild trout enthusiasts, you held this belief yourself, I would place it as:

Appeal to the extreme, and approaching reductio ad absurdum. You could also include sweeping generalization. If you asked me to prove you wrong, it'd be an appeal to ignorance.

The statement in quotes was something Jack wrote.

I like your description of what Jack's wrote, though.

"reductio ad absurdum", "sweeping generalization", "appeal to ignorance"

All that. Good stuff.

 

[k-bob]

interesting powerpoint from Michigan on possible effect of a harvest-reg increase for brook trout from 5 to 10 in upper peninsula streams ...

http://tinyurl.com/lkcfjal

they figure such a reg change would have "minimal effects" on the population, in part because the ST have "high natural mortality in older individuals" and "no shortage of spawners."

similar to PA small stream ST: release a caught fish with a high chance of not living another year due to natural causes, and it probably doesn't get recycled in other fisherman's catches much (behnke book and irish website link above)

I am not arguing for a higher ST creel limit in PA, but changing harvest regs for small stream ST may not be the biggest bang for your brookie-backing buck..

 

[Chaz]

An interesting statement was made at the meeting of the PA Trout Trout Management Committee, that PFBC didn't stock fish less than 9 inches. My immediate response was, why then allow the harvest of trout to begin at 7 inches, that kills a lot of wild fish un-necessarily.
If you continue to remove all of the >7inch brook trout from our streams, you will continue to have only mostly small brook trout in those streams.

 

[KenU]

Minimum size and high creel limits are not the way to go! Selectively removing larger fish from the gene pool removes the more successful brookies; i.e., those with the smarts and genetics that enable them to reach old age and maximum size. When a race horse wins the Triple Crown he is put out to stud, not ground up into pet food.

Nature doesn't do it this way. She takes out the small and immature and the weak first. According to Life History Theory, when larger size becomes less likely, genetics shift in order to favor early sexual maturity, short life span and therefore reduced size. So Ma Nature will compensate. She will change the gene pool to favor dinks. Brook trout have a very large and flexible gene pool . Why take out the larger fish? Don't we want them to get any bigger?

 

[k-bob]

are the small number (maybe 5%) of brookies in a pa headwaters stream that reach legal size really different genetically in some way that is connected to their relatively large size and would tend to be passed on to their offspring? maybe they are just the fish that happened to live longer or otherwise wind up bigger through luck... not really buying it...

 

[Chaz]

The larger brookies would have been the first brookies removed and that was over 100 years ago in most drainages. Brookies are like any other trout, if you keep removing the largest from the gene pool, you select fish for other traits. It's an unintended result, but that's the way it works.
That's more than likely why most streams don't have many > 8 inch fish and a 10 inch fish is big. Bigger trout mature later and grow faster, growth slows down when they start spawning. The largest brookies we know of now are in Labrador, they mature after 5 years of age or later. they also grown up to over 12 pounds and can be 30 inches long.
Right now you'd be hard pressed to find any brookies that weren't in Big Spring over 14 inches.

 

[JackM]

It's 90% luck.

 

[k-bob]

KenU "Selectively removing larger fish from the gene pool removes the more successful brookies; i.e., those with the smarts and genetics that enable them to reach old age and maximum size."

first, it is not clear that the brookies which reach legal size do so because of genetics. take two brookies with the same genes; the heron gets one, the other one gets away. ...

even if I assume there's a genetic reason why some brookies reach legal size while most dont, remember that the _bigger_ fish are harvested. so they have probably already spawned. (you would cut off genetic influence of harvested fish much more by keeping small fish that had never spawned.)

in a small pa st streams, the fish grow slowly and only live about three years. a 7" legal brookie harvested in its 3rd year of life has probably spawned on one of the two years it would likely have been around to spawn.

assume it's harvested in the summer and had a 60% chance living to spawn again (w/ 30% annual survival, there's 60% half-year survival). so that third year-harvest has a 60% chance of removing half of the fishes spawning years (that is, the second of two). so there's 30% less genetic influence from the fish (60% chance of losing half). if half of the legal brookies in a stream are so harvested, there's still 85% of their spawning influence...

not really buying the idea that brookie genetics are strongly slanted to smaller fish in this way...

 

[Chaz]

The brook trout in PA have been selected for fast maturity and small maximum size by the fact that we keep removing the faster growing, larger, slower maturing fish.

 

[k-bob]

still not sure that brookies are smaller today because their genetics have been affected by the harvest of bigger fish.. from kenUs article on old time ST fishing accounts:

"Brookies that lived year-round in the smaller upstream waters
were called hemlock trout and were brilliantly colored, big-headed and slender … the same as those familiar to most Pennsylvania anglers of today. They seldom exceeded 10 inches in length." the next paragraph starts "This is the way it was in Pennsylvania until shortly after the turn of the century. "

shouldnt the small stream brookies in the old days - before we messed their genes up by selectively harvesting bigger fish over many decades - have been bigger than they are now, not the same?

imho small-stream ST are small because they grow slowly and dont live long. ...

 

[JackM]

Chaz, I think what is being said is that habitat and fertility is the greater issue of even the slightest genetic slanting of the gene pool. And, I agree. Change the conditions and you will have sufficient genes in the pool to revert to a different growth and maturity curve. Change the harvest regulations and you will change practical nothing, as the research shows.

 

[Chaz]

Jack,
I have many times said that habitat is a factor, fertility not so much, because there are AMD streams that produce large brookies that aren't fished because they are AMD streams. There are also a couple of limestone streams that are brookies only that produce large fish.
The larger brook trout of the past were fast growing larger trout than today that matured later in life extending the growth and lived longer then the trout we have today. Brookie growth is slower after sexual maturity. Todays brook trout mature by 2 years of age in most populations, therefore 5 and 6 inch fish are reproducing at the expense of size.
Some streams have so many brook trout that I believe that they are probably stunted by resources. I believe Devils Hole is like that. It has a tremendous number of fish, but the size is only up to about 8 inches.
Yes a small infertile stream is likely to produce small trout because the conditions aren't there for big fish. But that explanation doesn't hold for all brookie streams. There are entire drainages of brookie streams that have high numbers of fish that still produce larger brookies in decent numbers that are fertile, but still the size of the fish limits out around 12 inches for most of the population.
The historic record is full of accounts of brookies larger than 12 inches especially in the big freestone streams. Those fish are gone and it isn't related to fertility.

 

[PennKev]

Chaz,

You are saying the trout of old were faster growing and also saying they inhabited larger waterways....

Do you not see the correlation?

Larger waterways generally are more "fertile," there is simply more forage. Whether due to different water chemistry or just simply being more habitat available to produce forage.

I don't know what you are getting at with the use of limestone's as an example. They tend to produce bigger fish precisely because they are fertile.

Additionally, is it not possible that in your AMD example, that the fish are growing larger because there are far fewer of them? The AMD suppresses population leading to less competition for available forage and habitat.

Kev

 

[JackM]

Chaz: "The historic record is full of accounts of brookies larger than 12 inches especially in the big freestone streams. Those fish are gone and it isn't related to fertility."

And so you think it is over harvest?

 

[salmonoid]

JackM wrote:
Chaz: "The historic record is full of accounts of brookies larger than 12 inches especially in the big freestone streams. Those fish are gone and it isn't related to fertility."

And so you think it is over harvest?

I've read some of the historic accounts about fish in the 12-20" range being common. Charles Lose "The Vanishing Trout" comes to mind. I also know that history can be exaggerated and fisherpeople tend to stretch sizes. Is anyone aware of old scientific literature or the predecessor of the PFBC studies that would corroborate the historic record of these sizes?

 

[JackM]

The habitat is degraded. Again, nothing to do with harvest. Now, Chaz' other point about stocking-over has continued validity, but not over harvest.

 

[k-bob]

looked at behnke's Trout and Salmon, chapter on brook tout:

"Adult length in dense slow-growing populations is attained at 5-7 inches." ... "In a typical small-stream population, brook trout will sexually mature and spawn at a young age of two years. In dense, small-stream populations, few live beyond three years."

a headwaters PA brookie big enough to be harvested has probably already spawned. so its genes arent removed from future fish. it is not certain that harvest prevents it from spawning again, because it may not have lived long enough to spawn again.

this assumes genetics are connected to fish size in the first place.