Creel limit changes: typically not the effect that you might expect

[The_Sasquatch]

So are you guys saying that the premise that a super high biomass of fish in a small stream stunts the growth of fish is completely wrong?

I've been discussing this on a board for fishing in the Smokies. Many of them harvest down there. Several believe it is helpful to bringing back "larger" fish. One person said, "In a normal stream where you might have 300 trout per mile, I wouldn't advocate harvesting. In our streams we have anywhere from 3500-4500 fish per mile."

 

[Squaretail]

Oh crap, I forgot about that. When are you going again? I'm going down towards the end of October thanks to recent events.
Be cool to hook up down there.
My experience has shown that what you say holds sand, but only in the smaller/smallest infertile streams.
Think Falling Springs and Big Springs. Plenty small but chock full of food. Plenty of trout. Quite a few bigguns.
You fish hard enough down there in the Smokies and sooner or later instead of the smaller bows and brookies, you'll bump into one whale of a brown.

 

[FarmerDave]

There is no doubt that you can manipulate size through harvest.

A given body of water can handle a certain biomass. The word is Biomass, not numbers.

My harvesting mid size fish, you do increase the potential sizes. This is especially true with impoundments, but also true in streams to varying degrees. But I also agree with Squaretail that streams with extremely high fertility such as Spring Creek would be much harder to manipulate through this method especially since the anglers wouldn't follow the recommendations anyway.

 

[troutbert]

The_Sasquatch wrote:
So are you guys saying that the premise that a super high biomass of fish in a small stream stunts the growth of fish is completely wrong?

I've been discussing this on a board for fishing in the Smokies. Many of them harvest down there. Several believe it is helpful to bringing back "larger" fish. One person said, "In a normal stream where you might have 300 trout per mile, I wouldn't advocate harvesting. In our streams we have anywhere from 3500-4500 fish per mile."

In PA, and elsewhere, if you make enough effort, you can find streams that are very lightly exploited, much less than average.

And what you find on those streams does not support your theory. The fish are not stunted. What you find are more LARGE trout than usual. And the fish are in good condition. They have not over-populated.

This is true of both brook trout and browns, but especially brook trout, because brook trout are easier to catch, so more vulnerable to getting cropped off at 7 inches.

So, what's the explanation? Why don't they over-populate? The reason is that where many of trout are allowed to live long enough to grow large, these big fish control the population through cannabilism.

The spawning produces more young fish than is needed to occupy all the slots in the stream, but the excess simply gets eaten.

And the reason there are more large trout in these streams is simply that it takes years for trout to grow large, and where they are not getting harvested, their odds of reaching an advanced age are much greater.

For ages anglers have gone to great lengths to fish places where very other people fish. Hiking into the wilderness, going on horseback, flying planes and helicopters at great expense etc.

And they do this so they can find places with big fish, and lots of them. If such very lightly exploited fisheries were all over-populated by skinny, stunted fish, people wouldn't go to such efforts.

 

[FarmerDave]

I cut my teeth on small infertile and unstocked NWPA brookie streams that were remote and very lightly exploited and have caught many big headed 5 - 6 inch trout complete with exposed gills.

You were saying?...

Why does it always have to be all or none with you?

You absolutely can manipulate a characteristic such as size through various harvesting practices. It is actually not difficult at all in an impoundment. But I do agree it would be extremely difficult in a highly fertile limestone spring creek.

But I certainly would not recommend a bunch of people on a chat board to start harvesting to improve the size because it would likely be much easier to screw it up than to improve it.

 

[The_Sasquatch]

Squaretail wrote:
Oh crap, I forgot about that. When are you going again? I'm going down towards the end of October thanks to recent events.
Be cool to hook up down there.
My experience has shown that what you say holds sand, but only in the smaller/smallest infertile streams.
Think Falling Springs and Big Springs. Plenty small but chock full of food. Plenty of trout. Quite a few bigguns.
You fish hard enough down there in the Smokies and sooner or later instead of the smaller bows and brookies, you'll bump into one whale of a brown.

I'm going down on Oct. 10th. You're going down during prime "leafer" season hahaha! Too bad we'll be missing each other. Although the irony of having to drive 10 hours to finally fish together when we live relatively close would be pretty rich ;-)

We've talked about Spring before, and from what I've read by members on this board who are old enought to have fished it before the biomass kill was that it had fewer fish back in the day, but bigger fish. This is why I bring it up now.

 

[pcray1231]

I think it is very hard to speak in terms of generalities on such a subject. Every stream is different. I recognize the difficulty of having different management for every single stream, and I'm not saying we should. But when you don't, different streams need different things, and on any topic, one guy will say, "well, on this stream this change resulted in this", and another will say "yeah, but on this one it resulted in this." They're both right.

I can poke holes in research. For instance, the assessment of harvested fish being the same despite lower creel limits. As was mentioned, it coincided with a stocking reduction. So it doesn't answer the question of whether it would have had an effect had all other variables been even.

Or, when stocking was ended, 6 out of 11 streams gaining population, and 5/11 losing population. That may not be "no discernable effect". On the contrary, it's a positive effect for 6 streams, and a negative one for 5 streams. They are different streams! Those effects may be very real, just different in different places. The next step isn't to offer a final conclusion. It's to figure out WHY it helped 6 streams and hurt 5 of them. If it turns out to be random variation, fine. If it turns out to be real, then apply what you learn to other streams.

But yes, there are streams where harvest harms the wild trout populations, in at least certain parts of the season. There are streams where it culls the larger wild trout, perhaps not hurting the population numbers but hurting the size distribution of it, resulting in more smaller fish. And there are streams that are already overpopulated, and a little harvest could IMPROVE the stream.

Every stream is different. Don't try to fit them all in a shoebox. And don't push global declarations like "harvest hurts wild trout populations" or "harvest doesn't affect wild trout populations", because neither is true all of the time.

 

[Chaz]

IT is not the number of fish in a stream that stunts growth but the number of times fish are caught in a year, that crops the fish. In other words each time a trout is caught it is more likely to succomb to mortality because of being caught.
Nearly any stream that is somewhat fertile has a nearly endless supply of food, the biomass of trout would have to be huge for the trout to be stunted by overpopulation.

 

[Chaz]

JackM wrote:
Well, I don't think he is stupid. Larger trout require more food. Forage is rare in most Brook Trout streams. Taking a couple here and there may actually help, but will not likely hurt the stream.

To get large trout the food has to be larger and the trout have to be inclined to eat larger and larger prey. Not all trout make the transition, in fact from what I see in the surveys, I'd say that most of our brown trout don't make the transition to larger prey, so they top out at about 14 inches, or are caught so many times they die from being caught so many times.
In other words it's not that the prey isn't there, it's that the trout won't take the larger prey. For instance where I've caught numbers of large brook trout there has been abundant prey and big brookies to eat it. In these streams they aren't likely to take small prey unless it is so abundant that they can't afford to take the abundant prey. But there is a limit to the number of tricos or midges a large trout may eat and still grow, that limit appears in the surveys to be around 14 inches.

 

[pcray1231]

Chaz, I'm not sure that is particularly true.

Amount of total food does affect growth rate. While you could say that, for instance, a limestoner has an endless supply of food, if that were so, would they not grow every bit as fast as say, a steelhead in Lake Erie? But they clearly don't. Steelhead grow much faster than browns in Penns Creek, which grow faster than browns in Spring Creek, which grow faster than browns in random medium sized freestoner, which grow faster than browns in tiny little mountain freestoner. Want bigger fish in a small stream? Fish upstream of the mouth where it runs into a river, or above a impoundment on the stream.

Why?

Part of it I think is simply space. Fish have a way of growing to the water they are in. For instance, a simple goldfish. Put him in a small bowl, and he grows to a certain size. Put him in a larger bowl, and he gets considerably bigger, even if you feed him the same.

And part of it is indeed food availability. Not all food forms are equal. And even if a stream has lots of food, that doesn't mean that all of it is available, or easily available. Certainly, you notice that certain lies grow bigger fish than others, even within the same stream. Do they grow faster there, or do bigger fish move in there? Either way, it supports the notion. If they grow faster there, then presumably a "good" lie presents more food for less energy used.

I certainly do think that some streams get overpopulated. You see fish jockey for best position all the time. The winner, more often than not, for the best spot is the biggest fish. Meaning the smaller ones get pushed to lesser spots. If the main draw of "spots" is protection from predators, then that means the little ones that got pushed to the margins get eaten, and the size structure is good. We would say it is not overpopulated, thanks to predation (harvest). If the main draw is food, then the little one's pushed to the margins survive, but just do not grow much, and you have a whole bunch of little malnourished fish with only a few bigger ones. This is an overpopulated stream.

Both situations happen.

Certainly, those who manage ponds will recognize the effect of "harvest" with panfish. If you have a little farm pond and stock bluegills, they will quickly overpopulate, and you have a lot of little bluegills. Want bigger ones? Add bass. Bluegill numbers plummet, but what's left grows much, much bigger.

The part of management that I struggle with is the idea that harvesting the LARGE fish improves the stream. If the harvest is supposed to reduce overpopulation and improve the size structure, then you want to harvest the little guys. Should be a respectable fish in just about every good lie, but that's it, not a million little one's in crappy lies.

 

[Chaz]

pcray1231 wrote:
Chaz, I'm not sure that is particularly true.

Amount of total food does affect growth rate. While you could say that, for instance, a limestoner has an endless supply of food, if that were so, would they not grow every bit as fast as say, a steelhead in Lake Erie? But they clearly don't. Steelhead grow much faster than browns in Penns Creek, which grow faster than browns in Spring Creek, which grow faster than browns in random medium sized freestoner, which grow faster than browns in tiny little mountain freestoner. Want bigger fish in a small stream? Fish upstream of the mouth where it runs into a river, or above a impoundment on the stream.

Why?

Part of it I think is simply space. Fish have a way of growing to the water they are in. For instance, a simple goldfish. Put him in a small bowl, and he grows to a certain size. Put him in a larger bowl, and he gets considerably bigger, even if you feed him the same.

And part of it is indeed food availability. Not all food forms are equal. And even if a stream has lots of food, that doesn't mean that all of it is available, or easily available. Certainly, you notice that certain lies grow bigger fish than others, even within the same stream. Do they grow faster there, or do bigger fish move in there? Either way, it supports the notion. If they grow faster there, then presumably a "good" lie presents more food for less energy used.

I certainly do think that some streams get overpopulated. You see fish jockey for best position all the time. The winner, more often than not, for the best spot is the biggest fish. Meaning the smaller ones get pushed to lesser spots. If the main draw of "spots" is protection from predators, then that means the little ones that got pushed to the margins get eaten, and the size structure is good. We would say it is not overpopulated, thanks to predation (harvest). If the main draw is food, then the little one's pushed to the margins survive, but just do not grow much, and you have a whole bunch of little malnourished fish with only a few bigger ones. This is an overpopulated stream.

Both situations happen.

Certainly, those who manage ponds will recognize the effect of "harvest" with panfish. If you have a little farm pond and stock bluegills, they will quickly overpopulate, and you have a lot of little bluegills. Want bigger ones? Add bass. Bluegill numbers plummet, but what's left grows much, much bigger.

The part of management that I struggle with is the idea that harvesting the LARGE fish improves the stream. If the harvest is supposed to reduce overpopulation and improve the size structure, then you want to harvest the little guys. Should be a respectable fish in just about every good lie, but that's it, not a million little one's in crappy lies.

Trout have tomake the transition to larger prey to grow large, they cannot keep eating insects all there lives and contiue to grow, at some point they will start using as much energy to catch the insects they eat as they gain by eating them. Space is a factor, and that comes in the form of habitat. There has to be big fish lies in a stream for it to support big fish. So in part we agree.


edit;

The idea that harvesting big fish will create more big fish is weird science, those big fish genes have to remain in the gene pool for fish to grow large. you remove fish of all sizes and you get a better combination of fish sizes than if you harvest the only the big ones or only the small ones.
What we have left after 100 years of harvest at 6 inches is a lot of

 

[FarmerDave]

Chaz wrote:

Trout have tomake the transition to larger prey to grow large, they cannot keep eating insects all there lives and contiue to grow, at some point they will start using as much energy to catch the insects they eat as they gain by eating them. Space is a factor, and that comes in the form of habitat. There has to be big fish lies in a stream for it to support big fish. So in part we agree.

Parts of that are true, but you give trout too much credit for brain power. It isn't like a conscious decision. Hell, I've seen brook trout bat around a pieced of a twig trying to eat it. The transition occurs without thought or effort. It' sinstinct and happens without thought.

edit;

The idea that harvesting big fish will create more big fish is weird science,

Yes it is. But what about slot limits (Harvest of only medium sized fish). They have been proven to work in many instances.

But as Pat said, all streams are different.

those big fish genes have to remain in the gene pool for fish to grow large. you remove fish of all sizes and you get a better combination of fish sizes than if you harvest the only the big ones or only the small ones.
What we have left after 100 years of harvest at 6 inches is a lot of

 

[The_Sasquatch]

Okay...I'm not advocating the idea that harvesting "BIG" fish will lead to more, bigger fish. I think the post I responded to said, "nice", not "big". I don't associate the two.

 

[The_Sasquatch]

Correction: he said "fine specimins". That, in no way to me, indicates that they were large fish.

 

[pcray1231]

Trout have tomake the transition to larger prey to grow large, they cannot keep eating insects all there lives and contiue to grow, at some point they will start using as much energy to catch the insects they eat as they gain by eating them.

So you do admit that food availability plays a big part. As FD said, the fish don't do it consciously. Once they reach a certain size, if baitfish are available, they eat them. If not, they don't, and continue eating bugs. But the availability of baitfish is indeed related to the stream itself.

What I was railing against was your assertion that food in an even somewhat fertile waterway has a "nearly endless" supply of food. i.e. it would follow that from a food standpoint it can handle more fish, and bigger fish. The limiting factor would thus be management practices and/or holding lies to avoid predation.

I just don't think that's true. It CAN be true sometimes. But the food supply isn't endless, or else the growth rates would be the same in all at least semi-fertile waters. They are not, they vary widely even between very fertile waters.

I won't argue that changes in management could help some streams, but there are quite a few that are about as good as they can be. They are what they are.

 

[FarmerDave]

The_Sasquatch wrote:
Correction: he said "fine specimins". That, in no way to me, indicates that they were large fish.

Right. Those would fall under mighty fine.