Trout size

[rrt]

Lark,

Some of us believe that overfishing and thus overhandling of the fish is a cause of this. If the fish are handled too often, it would seem that they succumb from the stress of that, at least that is what we believe. When I fished Spring many years ago, there were many nice trout. The last few times I managed to squeeze in there, the fish were much smaller -- and as you noted, the habitat was the same -- except for where the powers that be removed the West Penn and McCoy dams which provided great trout habitat, esp behind the McCoy dam. There were great trout there, and even I managed to land a few of them.

But, on the other places on Spring where I used to catch some nice trout, there were few the last few times I fished there. I believe, as some others do, that the stress of overhandling them caused early mortality.

I cannot speak to Penns; I only ever fished there a couple of times.

I have noticed the same phenomenon on a couple of other streams where increasing pressure resulted in fewer, smaller fish, too.

 

[jifigz]

The obvious requirements for big trout have been stated. Adequate food supply, excellent holding water/cover, a variety of habitat, and prime spawning areas. I can think of examples that both support and negate many of the previous comments.

I too believe that too many trout in a stream is a bad thing for producing large fish. I also think that a mixture of habitats is extremely important to "nurture" the fish through each stage of life. Once a fish reaches a large size of course it muscles its way into the prime water offering cover, depth, and security.

I know of a stream that does not hold all that many fish, seems to have not the best opportunities for food and is rather lifeless in places, yet big trout are there year round. Other streams like Penns and the Little J have plenty of fish, plenty of food, and plenty of above average trout. Those trout are often in places that make them too hard for the angler to reach and catch with consistency of to get your flies presented correctly. I honestly don't think that a genetics play much or a role. I bet we'd all be surprised by how many large trout there are in a lot of places and just how bad we are at catching them with our equipment given where they reside.

 

[larkmark]

rrt- I have had the same hunch about what happened at Spring. It is hard to watch it pounded day after day all year long. The same has happened to an extent on Penns too. Guides taking clients day after day along with the normal year around pounding. Those creeks are fish and bug factories but all that pressure is making them small fish fisheries despite having good food and habitat and regulations.

 

[redietz]

ryansheehan wrote:
[

Troutbert, I would say the trophy fish occupied those places because they have grown big . I would not say that those fish became big because of those places. Those large fish have not occupied those prime lies their entire life. They started in the thin water, then moved to a little deeper run and so on. As long as there was enough food for them to grow they would continue to move up in the pecking order. If there were limited food sources the trout in the most prime lies would not be that big. I've seen enough large fish in small spring creeks that are easily seen from overhead to make me realize more that cover is not the most important aspect. There are certainly many factors but take away food and nothing else matters.

Exactly. The fact that the biggest fish inhabit the best lies explains the distribution of fish within a stream; it says nothing about the capacity of the stream to produce fish of any given size.

 

[SteveG]

Food. It's why the largest trout are found spending most of their time in larger "warm-water" creeks/rivers, or lakes. Flip a few rocks over on our larger rivers, and while the water may not be "pristine" in regard to pollution, the biomass is undeniable. I feel that habitat is a distant 2nd place.

 

[fishhead]

I fish many "marginal trout waters" in Pa and surrounding states when hunting for large fish. Find marginal WW fisheries connected to or at least in the same watershed as healthy CW fisheries and they are there. Most of the places i have found them are LOADED with "forage fish" such as chubs,redhorse,grass carp and fallfish in the 5-8"range as well as huge crayfish populations. December thru february are the main times that i target fish on these waters, but have run into some very large fish while SMB fishing with my sons even in the summer. I believe many of these fish move considerable distances more than most folks realize.

 

[silverfox]

I've read that in New Zealand, the primary reason for all the huge fish is the water temperature fluctuations. In that there isn't much of one. Most of their rivers and lakes maintain an almost yearly constant temperature right in trout's optimal temperature zone.

I'm sure other factors contribute too, but that makes a lot of sense to me personally. If they aren't stressed, or stressed very little, they'll grow at an optimal rate.

Of course, there's more to it than that. If you have a tiny mountain trickle in PA that maintains a constant temperature, you're not going to get 25 inch brook trout. Need habitat, food and water chemistry. If you have all those things plus a constant optimal water temperature, you get tons of huge fish. Remove any one of those factors and you get mostly small fish.

 

[troutbert]

redietz wrote:

ryansheehan wrote:
[

Troutbert, I would say the trophy fish occupied those places because they have grown big . I would not say that those fish became big because of those places. Those large fish have not occupied those prime lies their entire life. They started in the thin water, then moved to a little deeper run and so on. As long as there was enough food for them to grow they would continue to move up in the pecking order. If there were limited food sources the trout in the most prime lies would not be that big. I've seen enough large fish in small spring creeks that are easily seen from overhead to make me realize more that cover is not the most important aspect. There are certainly many factors but take away food and nothing else matters.

Exactly. The fact that the biggest fish inhabit the best lies explains the distribution of fish within a stream; it says nothing about the capacity of the stream to produce fish of any given size.

Going back to the Young Womans Creek example I discussed earlier, if YWC had no prime habitat spots its entire length, it would not have large trout.

In the "thin" habitat areas, the trout would not grow large.

The physical habitat has a huge influence on the ability of the stream to produce large trout.

It also has a huge influence on the overall quantity of trout the stream supports, measured as kilograms per hectare (the units the PFBC uses) or pounds per acre.

 

[dryflyguy]

I agree with habitat and forage being the largest factors.

However, constant temps seem to be important too
And present a prime example: the clarion river, in the special regs area between Johnsonburg and Ridgeway - which holds many large fish.

It's not a very large stream in this stretch - roughly about the size of the lower section of spring creek.

Habitat is OK IMO - some deep holes, but also a lot of skinny water.
And I have caught many large fish in those shallow stretches

Hatches are very sparse there. So I guess, the fish feed mainly on chubs and crayfish. But I do manage to catch my share on dry flies

Sounds like many other streams I know.
However, the one difference here, is the giant paper plant in Johnsonburg.

It discharges a lot of warm water that is used in their manufacturing process 24 hours/day - 7 days a week.
And keeps the stream open and at a moderate temp all winter long.
Allowing the fish to feed more and stay active right through the winter
That's my theory, anyway.

I do know this - I've fished both branches above the paper plant. And long stretches below Ridgeway.
And haven't caught anywhere close to the amount of large fish that I do in that 7 mile section

 

[MKern]

The same reason humans are various sizes: genetics.

But of course, food and habitat play a factor....just like humans that occupy different countries.

But I agree that the largest fish occupy the best lies because they are the biggest fish.

 

[PennKev]

dryflyguy wrote:
I agree with habitat and forage being the largest factors.

However, constant temps seem to be important too
And present a prime example: the clarion river, in the special regs area between Johnsonburg and Ridgeway - which holds many large fish.

I think you are on the right track in regard to moderation of temps as an important factor. I firmly believe that length of "growing season" is vital in determining trout size. I think a limiting factor for many of our waters in PA is the amount of days each year in which conditions are favorable for trout growth. Not survival, but growth. I think that even in many creeks where wild trout are abundant, the water temps spend too much time above a level at which trout grow well or below which trout are active.

When people wonder why large trout are more abundant in the west (or other places), I think what is missing is a comparison of how much of the year provides conditions favorable to growth.
As a point of reference, westerners have a lower threshold for what they consider "too warm for trout." For example, the infamous "hoot owl" restrictions take effect when water temps REACH 73 degrees on 3 consecutive days. The key word being "reach," as during these periods the water temps actually spend much of the time in the low to mid 60's. The takeaway being that even during very hot summers, the water temps are generally better than what we see in some of our better streams on a regular basis during "normal" summers.

What you get in the case of the west is a growing season that begins shortly after ice-out and lasts into summer with minimal interruption before resuming in September. In comparison I think that PA generally has a short spring growing season that often ends abruptly in early June, if not sooner, then resumes relatively late. Sometimes as late as October before growth slows again for the winter.
Another key factor is that our water temps, once elevated, tend to hover near the threshold at which trout are losing weight, if not staying above that threshold for extended periods encompassing days or even weeks. In many western waters, that threshold is approached and exceeded for much shorter periods before returning to much lower temps. This can be a daily cycle. Temps can dip below 60 and peak above 70 in a single day. Keep in mid this is would often be considered the worst conditions of the year on many western waters.

While we are blessed with many spring creeks and several spring creek influenced watersheds, we need not look any further than the yearly fretting over water temps on some of our "best" waters to recognize that temps over the course of a season could be a limiting factor to trout growth, even though wild trout are abundant.

 

[Hook_Jaw]

The biggest trout usually live where there's not a lot of trout

 

[marcq]

Maybe I should of made this post about valley because I keep referring to it as my baseline stream with a lot of smaller fish and few big but that’s besides the point. It just the stream I’m most familiar with.
I’m starting to see a trend after reading everyone post and thinking about my experience. The biggest fish come from marginal streams because they have more baitfish and other forage like crayfish leeches basically bigger meals. Now look at limestone creeks like valley creek and streams like it. they seem to lack large forage like crayfish, leeches and baitfish beside small trout. One species the that thrives in limestone creeks are sculpin. I’ve never witnessed them on valley creek. I’ve seen them in big spring. A creek known to have large fish. Read that sculpin were stocked by PAFB into codorus creek. That’s stream is half the size of valley and has a trophy section and I think valley has a fare about of holes and water to hold large fish. Would PAFB ever consider introducing a species on a class a water to possibly make it a better stream?

 

[gulfgreyhound]

I posed the question of why New Zealand trout get so large to a gentleman who works for The New Zealand Fish and Game folks and this is his response:
There will be a lot of people more qualified on this subject than me but heres some thoughts you would be welcome to put up on your website if you like.

Food and temperature would be two major reasons. When trout were first released in NZ they grew to very large sizes feeding on an abundance of small native fish. These days significant mice (due to beach tree seed events) cicadas and whitebait (small native fish) seasons still result in trout putting on a lot of weight quickly.

The temperature regime in many NZ rivers would help a lot as well. Often in the 12-16 degrees Celsius range which is good for brown trout growth. Some of our Otago streams may get as high as 19-21 on a mid-summer day but generally cool off overnight which would help to reduce stress. I’m aware that some north American streams will remain hot over night as well?

I’m sure there’s a density dependant relationship. In rivers/lakes with lots of spawning grounds the number of trout may be high but often the average size is lower than systems with less spawning potential and/or frequent disturbance events such as drought or floods. In Lake Onslow which has a lot of spawning streams the average brown trout length is around 30cm in the nearby Poolburn Dam which only has two small spawning streams the average size is around 50cm.

Longevity also helps. In the Nevis River in Otago, the brown trout can reach large sizes even though the population in the upper river is isolated (from a large water body/potential food source) and the winters are quite cold. We did some otolith analysis and found that some of the trout were up to 12 years old. We also thought some were not spawning every year so the cost of reproduction on energy reserves (which can tax 50% of energy reserves). Delayed maturity may also assist trout in growing to a large size, perhaps especially with rainbows.

The variable life history of brown trout helps some fish to attain large sizes. River born browns can migrate to the sea or an estuary/lake (with lots of bait fish resources) and then return to reside in an upper river.

I also wonder if we have less large avian predators (no swooping eagles etc) than many north American systems which allows NZ trout to feed more frequently in rivers during daylight hours and put on weight. Although we do have a cormorant and a species of heron that feeds on trout but many small ones which probably often helps to reduce competition between fish and increase average sizes.

More to follow.
GG

 

[ryansheehan]

I've spent alot of time on the Gunpowder so I guess this is where alot of my ideas are coming from. The gunpowder below the dam has very great temps, , good cover and deep holes(even at low flows). The one thing it lacks on the upper section is good forage and it has mostly small fish. There are definitely large fish but as we talked about they tend to be in the more marginal water further down stream.

 

[MarkC]

The Gunpowder was interesting to watch make the transition from a marginal trout stream which about ran dry every year, to a tailwater with minimum flows. The first few years of tailwater releases the few trout around grew quickly but there wasn’t many of them. The fish left had the whole habitat to themselves, especially lower down.

My friend and I were the only two fisherman I ever saw on one stretch for years. The trout peaked about 18” (my top fish was a 24” rainbow that had probably been stocked as a 12” fish) with maybe one fish per 100 yards of stream. Each had a spot of cover they would emerge from to feed anywhere along their stretch (the trout by the log, the trout by the bush), and they were spooky as hell. We called it our New Zealand fishing.

Then conditions for spawning became ideal and within a few years the large trout were gone, replaced by lots of little guys that inhabit the stream now. There seems to be more pounds of trout now, not sure if it’s stunting or over population. Some of the hatches also disappeared, here again perhaps there’s more bug biomass, it’s just different (no more weeklong blanket Grannom hatch below were the little falls dumps in).

Mark C

 

[wbranch]

Ryansheehan wrote;

I feel like the reason I catch big browns in marginal trout water(tempature wise) is the abundance of forage that can support their needs. There are certainly many factors but I would rate this as number one.

Spot on 100%. Abundant food sources, and the addition of regulated water flows and temperatures, will grow and sustain large numbers of big trout.