The trout's diet...
 

Tom G wrote:

Now I'm wondering about the lack of survival skills in hatchery fish.
How many of them fail to thrive in the wild because they don't know
how/what to eat?

I think it goes beyond that but I did read about a study that tried to
do what you're suggesting - I can't remember the results.

Most trout that are raised to catchable size before stocking are from
lines of fish that were developed to do well in hatchery runs (at least
this is true in Colorado). They selectively bred for fish that would
gain the most weight in the shortest amount of time in a runway
environment. It pretty obvious to me that those fish aren't going to do
well in a natural environment even if they know what to eat.

Willi

The trout's diet...
 

Wolfgang wrote:


As for sustaining an arbitrary wild fish population, I once spoke
to a trout researcher who surveyed quite a few streams in Mexico,
and he stated that he did not believe it was possible to exterminate
a wild population merely by hook+line fishing. Down there he did
see fishing, even flyfished with the local 3-person flyfishing club,
and any fish caught was _always_ kept. Yes, the trout populations
were very low. Yes, the fish were very small. But they were there.


Lots of experts throughout history were certain that [insert critter of
choice here] could not possibly exterminated by means of [insert method of
choice here]. They were wrong. Always. Evidently, some things don't
change.


In absolute terms it is possible but it would be TOUGH to exterminate a
viable trout population with just hook and line. However, in most
places, it isn't difficult to severely lower the population. The
extermination of all the native trout I'm aware of, was either caused by
changes in the environment like increased water temperature, pollution,
etc or the leading cause, in most cases, the introduction of non native
trout and other fishes.

Willi

The trout's diet...
 

RDean notes:
Tonight, shrimp remoulade, crawfish bisque, FRESH pistolet, and the last
of the strawberries...yeah,

Oh, right! I run around town on errands like a fiend, choke down a couple
grilled cheeses with canned soup, and then have to suffer through this! At
least we do have a mess of very fine strawberries, and haven't gotten to the
last of them yet!
suffering remoulade envy,
Tom

The trout's diet...
 

"Willi" wrote in message
...

In absolute terms it is possible but it would be TOUGH to exterminate a
viable trout population with just hook and line.

The impossible is intractable.....it can sometimes take years. The TOUGH we
can do in about a month......in bad weather.

However, in most
places, it isn't difficult to severely lower the population.

I got a crew can do that in 72 hours on any trout stream in the world.

The
extermination of all the native trout I'm aware of, was either caused by
changes in the environment like increased water temperature, pollution,
etc or the leading cause, in most cases, the introduction of non native
trout and other fishes.

I can see no fault with that argument.

Wolfgang

The trout's diet...
 

"Willi" wrote in message
...


Tom G wrote:

Now I'm wondering about the lack of survival skills in hatchery fish.
How many of them fail to thrive in the wild because they don't know
how/what to eat?

I think it goes beyond that but I did read about a study that tried to
do what you're suggesting - I can't remember the results.

Most trout that are raised to catchable size before stocking are from
lines of fish that were developed to do well in hatchery runs (at least
this is true in Colorado). They selectively bred for fish that would
gain the most weight in the shortest amount of time in a runway
environment. It pretty obvious to me that those fish aren't going to do
well in a natural environment even if they know what to eat.

When fish are hungry, they WILL eat. I'm going to guess it doesn't take
them long to figure out the difference between a pebble and a plecopteran.
If they're thirty days from the hatchery and they're not dead?..........

Wolfgang

The trout's diet...
 

In article
d.umich.edu,
Mu Young Lee wrote:

On Mon, 14 Jun 2004, Tom G wrote:

Two of the trout had white flesh while the third had orange/pink flesh.
Not as pink as the (landlocked) Dolly Varden I used to catch in Alaska,
but distinctly _not_ white.

I have had similar experiences with brown trout in a little spring-fed
pond I used to fish. Early in the season the flesh was white. By August,
those that managed to survive the summer had pink/orange flesh.

That's quicker than I would have expected. Thanks for the info.
--
email:remove tt

The trout's diet...
 

Willi wrote in message ...

It pretty obvious to me that those fish aren't going to do
well in a natural environment even if they know what to eat.

I don't think that statement holds up as a blanket for all
situations. Fish are pretty basic lifeforms. Hatchery trout
(catchable size) do learn fairly quickly what to eat in the
wild, and other life skills such as flight. In relatively benign
environments, I think they can and do fill the carrying capacity
of that environment effectively. Fertile reservoirs, tailwaters,
etc., all can grow and sustain hatchery-based populations. We've
all caught even 1-year holdovers that were healthy and strong,
and were clearly adapted to their environment. In more harsh
environments, I would agree that a stocked catchable is starting
at a severe disadvantage, and the outlook is more dire.

I'm not saying hatcheries are always beneficial, that there's no
downside, that they don't impact wild populations, that catchable
stocking is good everywhere. But I think it's obvious that there
are waters where they do quite good and create viable fisheries
which might not exist otherwise.

Jon.

The trout's diet...
 

On Tue, 15 Jun 2004 18:50:41 -0500, "Wolfgang"
wrote:


"Willi" wrote in message
...


Tom G wrote:

Now I'm wondering about the lack of survival skills in hatchery fish.
How many of them fail to thrive in the wild because they don't know
how/what to eat?

I think it goes beyond that but I did read about a study that tried to
do what you're suggesting - I can't remember the results.

Most trout that are raised to catchable size before stocking are from
lines of fish that were developed to do well in hatchery runs (at least
this is true in Colorado). They selectively bred for fish that would
gain the most weight in the shortest amount of time in a runway
environment. It pretty obvious to me that those fish aren't going to do
well in a natural environment even if they know what to eat.

When fish are hungry, they WILL eat. I'm going to guess it doesn't take
them long to figure out the difference between a pebble and a plecopteran.
If they're thirty days from the hatchery and they're not dead?..........

Wolfgang

A couple weeks ago we kept some stocked fish from a local lake. There
is absolutely zero reproduction and I would guess little carryover
from year to year. They all had natural food in their stomachs ranging
from damselfly nymphs to midge pupa. From what I understand it is
instinctive behavior for trout to mouth things drifting in the water
column as a way of investigating them.


g.c.

The trout's diet...
 

In article ,
Willi wrote:



Tom G wrote:
Now I'm wondering about the lack of survival skills in hatchery fish.
How many of them fail to thrive in the wild because they don't know
how/what to eat?

I dont think they have a problem with eating. If anything, I think they
eat too much, I.E at first they eat garbage, like cigarrette butts,
weeds,etc. They will eat anything, and this includes nutritious food.
They dont starve, and after a while they figure out not to eat the
garbage.

I think the biggest thing to wipe them out is birds, they stay on top
and in groups and are easy prey. A second factor would be quickly being
caught by the bait chuckers.

The trout's diet...
 

Jonathan Cook wrote:

Willi wrote in message ...


It pretty obvious to me that those fish aren't going to do
well in a natural environment even if they know what to eat.


I don't think that statement holds up as a blanket for all
situations. Fish are pretty basic lifeforms. Hatchery trout
(catchable size) do learn fairly quickly what to eat in the
wild, and other life skills such as flight. In relatively benign
environments, I think they can and do fill the carrying capacity
of that environment effectively.

The Montana studies showed that dumping catchable on top of a self
sustaining population of trout can actually low the carrying capacity of
a river or stream.


Fertile reservoirs, tailwaters,
etc., all can grow and sustain hatchery-based populations. We've
all caught even 1-year holdovers that were healthy and strong,
and were clearly adapted to their environment. In more harsh
environments, I would agree that a stocked catchable is starting
at a severe disadvantage, and the outlook is more dire.

The percentage of catchables that makes it through the first season is
VERY low. In most situations where stocking is necessary, I favor
stocking of fingerlings. Much less expensive and it creates a more
"natural" situation.



I'm not saying hatcheries are always beneficial, that there's no
downside, that they don't impact wild populations, that catchable
stocking is good everywhere. But I think it's obvious that there
are waters where they do quite good and create viable fisheries
which might not exist otherwise.

I don't completely disagree. I think they're great in urban environments
that provide a place for kids to have some success. However, overall, I
would rather they manage those waters for fishes that can successfully
become self sustaining or make changes in the environment so that
reproduction is more successful.

Stocking catchables does sell licenses. However, with the cost of
raising trout to catchable size, I have trouble with the argument that
the DOW "makes money" on this. The increased revenue from the increased
license sales does allow the DOWs to be larger (which seems to be a goal
for all government agencies) but I would like to see a cost
effectiveness done.

Willi