Stock fish

As a few of people asked me about this, here is some information you
may find interesting.

There is considerable genetic diversity in wild fish, even among our
native brown trout in various river systems. Stocking fish from other
rivers or systems can, (and frequently has) , cause severe damage to
the local blood-line. This may have far reaching results, up to and
including the extinction of a species or sub species.

There are even more risks involved when stocking non-indigenous fish,
even in still waters. This is one reason so called "triploid" rainbows
are usually stocked in most waters in Europe. In many places it is
illegal to stock anything other than sterile fish anyway. Except in
running water, and using broodstock from the same bloodline. This is
carefully controlled amd monitored in most places.

Just like humans, fish have genetic building blocks gained from both
parents. Half these blocks come from the male parent, and half from
the female, and are generally referred to as genes.

Genes are basically programmed instructions to cells on how to produce
proteins. These instructions are contained in DNA strings. The
abbreviation "DNA" stands for DeoxyriboNucleic Acid. This is the
genetic material of a cell. The chromosomes inside the nucleus (the
control centre) of the cell are made of DNA. A very large amount of
DNA. It is very fine and tightly coiled but there may be as much as a
metre of DNA string in a single cell.

Different species have a different number of chromosomes containing
different numbers of genes. One set of genes, from one parent, is
referred to as a "haploid" set.

At the moment of fertilisation, egg and sperm combine their haploid
sets, and the resulting egg then has two complementary sets of genes,
and is referred to as "diploid". The resulting diploid fish will
develop into a normal fish, and upon reaching sexual maturity, will
reproduce normally.

However, if the egg is treated with a shock immediately after
fertilisation occurs, this produces a fish with three sets of
chromosomes, or a "triploid". This extra genetic code is form the
female parent, and is present before fertilisation. Normally, without
any extrenal treatment, this code disappears from the egg after
fertilisation. If the egg is subjected to a physical shock, such as a
pressure increase, or a temperature spike, or even just a good
shaking, this prevents the code from being ejected. This also occurs
in the wild, and is possibly a natural mechanism to prevent damaged
eggs being viable.

There is no genetic modification as such, no genes have been changed
or produced, but the number of chormosomes has been increased because
one female set was not lost after fertilisation. The egg now has
three sets of genetic information, instead of two.

Triploid fish grow and develop more or less normally, ( with some
exceptions, see below), but when they try to reproduce, the three sets
of genetic code can not divide properly, and no viable eggs or sperm
are produced.

This is also why at some fisheries, fish my be caught which are full
of eggs and milt! In a lot of cases this is reabsorbed by the fish,
given time, and in many other cases the fish simply die.

As described above, this is really only a basic and simplified model
of the process.Many species are naturally possessed of multiple
identical chromosome sets, "tetraploid" ( four sets),
"hexaploid" ( six sets), heptaploid ( seven sets) etc. When more than
diploid, the term usid is normally "polyploid".

In order to ensure triploidy, the exact point, type, and degree of
shocking is of paramount importance. Too small a shock and triploidy
does not occur, if the timing is wrong triploidy will also not occur.
Too much shock, and the eggs may be killed.

Furthermore, in any batch of eggs so treated, the incidence of
triploidy is never more than about 90% maximum,. and may be
considerably less. farmers have to inspect the fish carefully in
order to remove any hen fish, before these are stocked. Even so, any
particular batch of mature "triploids", may contain a few fertile
fish.

In order to ensure continued viability of a species in the wild, there
must be a sufficient number of that species in existence, and there
must also be sufficient genetic diversity to ensure their survival. A
few fertile hen fish in a particular enclosed water, are not
considered to be a major danger, but this is not to say that they will
not be!

Many of the original rainbow trout imported to the UK and elsewhere,
came form original Steelhead strins, most especially Shasta river
steelhead. This explains their genetically programmed propensity for
running to sea given the opportunity. There are a couple of places in
the UK, most notably the Wye, where rainbows breed natually and are a
vibale population. There are a couple of other less well know places,
which I don´t want to mention here. There are also a few places in
Europe where small natural populations have established themselves,
including a few still relatively small populations of sea-going fish.
Mainly in the Baltic region.

Increasingly large numbers of rainbows are caught in the Baltic sea
every year, and although the vast majority of these fish are escaped
triploids, there is a small percentage of fish which return to various
rivers and spawn.

It is often stated that triploid fish are stocked because of their
better growth rates. This is not the case. Better growth rates in
the majority of rainbow stock trout have been selected for over a
period of time. Fish with high growth rates are selected as parents,
their progeny is also selected, and so on. Of course, selecting for
certain traits may also produce other problems, and it does!

Basically all the fish produced in Europe for stocking purposes are
selectively bred fast growing fish reared to a certain size using
fishmeal.

( Extract and link)

QUOTE

What Is Fishmeal

Fishmeal is a generic term for a nutrient-rich feed ingredient used
primarily in diets for domestic animals, sometimes used as a high-
quality organic fertilizer. Fishmeal can be made from almost any type
of seafood but is generally manufactured from wild-caught, small
marine fish that contain a high percentage of bones and oil, and
usually deemed not suitable for direct human consumption. These fishes
are considered 'industrial' since most of them are caught for the sole
purpose of fishmeal and fish oil production. A small percentage of
fishmeal is rendered from the by-catch of other fisheries, and by-
products or trimmings created during processing (e.g., fish filleting
and cannery operations) of various seafood products destined for
direct human consumption.

UNQUOTE

http://www.thefishsite.com/articles/...aculture-diets

This has extremely unfortunate, and in many places disastrous effects
on the marine environment, as vast quantities of wild bait fish are
used to produce the fishmeal.

The stocked fish, assuming good water and feed conditions, continue to
grow at rapid rates, and even after a fairly short time may at least
outwardly be almost indistinguishable from normal wild fish. But, as
they are the product of extreme selection from a limited gene pool,
manipulation, and intensive rearing, they do not possess many of the
faculties or instincts of wild fish.

In the meantime, in order to supply the continuous demand for stocking
and other purposes on the European markets, and especially the UK
market which is one of the largest, fish eggs are imported form a
number of places. This is also because fish from different areas spawn
at different times of year. Although a large number of producers spawn
fish artificially all the year round from their initial brood stock,
large quantities of eggs are now imported from Denmark and South
Africa. Some eggs also come from America, Canada, Iceland and even
Australia, among others.

Although extremely controlled by the government, many people feel this
is a recipe for disaster just waiting to happen.

From the hatcheries, they are grown on to the size required by the
waters wishing to stock them, once again using large quantities of
fish meal obtained form wild marine protein, and also using intensive
rearing methods involving the heavy use of various drugs and
chemicals which are essentila to any intensive rearing environment, in
order to prevent or control disease and parasites. Most fish are also
fed added colouring agents to make their flesh colour more attractive
to the eventual consumers.

Once actually at the fisheries concerned, stocking policies vary. Some
waters may stock large contingents of fish in one go, often at the end
of winter. Other fisheries may have large holding ponds in which they
continue to feed the fish until required for "topping up" the water
with fish. Others obtain their fish form special holding farms, which
specialise in supplying stock fish for this purpose.



TL
MC

George?

I thought your heart gave out, old man. Welcome back. I fished with
your rod the other day. It doesn't compare to my other boos, but I'm
glad to have it. My best to Gladys.

The Pirate

On 16 Sep, 19:48, Dave LaCourse wrote:
George?

I thought your heart gave out, old man. Welcome back. I fished with
your rod the other day. It doesn't compare to my other boos, but I'm
glad to have it. My best to Gladys.

The Pirate

**** off Lacourse, if you have nothing constructive to contribute, you
should keep your mouth shut. You just finished making a complete ****
of yourself, and nobody wants to see a repeat. You can´t win a
****ing match anyway, your dick doesn´t work properly any more, and
that also seems to have affected your brain.

MC

On Sep 16, 8:08 am, Mike wrote:
As a few of people asked me about this, here is some information you
may find interesting.

There is considerable genetic diversity in wild fish, even among our
native brown trout in various river systems. Stocking fish from other
rivers or systems can, (and frequently has) , cause severe damage to
the local blood-line. This may have far reaching results, up to and
including the extinction of a species or sub species.

There are even more risks involved when stocking non-indigenous fish,
even in still waters. This is one reason so called "triploid" rainbows
are usually stocked in most waters in Europe. In many places it is
illegal to stock anything other than sterile fish anyway. Except in
running water, and using broodstock from the same bloodline. This is
carefully controlled amd monitored in most places.

Just like humans, fish have genetic building blocks gained from both
parents. Half these blocks come from the male parent, and half from
the female, and are generally referred to as genes.

Genes are basically programmed instructions to cells on how to produce
proteins. These instructions are contained in DNA strings. The
abbreviation "DNA" stands for DeoxyriboNucleic Acid. This is the
genetic material of a cell. The chromosomes inside the nucleus (the
control centre) of the cell are made of DNA. A very large amount of
DNA. It is very fine and tightly coiled but there may be as much as a
metre of DNA string in a single cell.

Different species have a different number of chromosomes containing
different numbers of genes. One set of genes, from one parent, is
referred to as a "haploid" set.

At the moment of fertilisation, egg and sperm combine their haploid
sets, and the resulting egg then has two complementary sets of genes,
and is referred to as "diploid". The resulting diploid fish will
develop into a normal fish, and upon reaching sexual maturity, will
reproduce normally.

However, if the egg is treated with a shock immediately after
fertilisation occurs, this produces a fish with three sets of
chromosomes, or a "triploid". This extra genetic code is form the
female parent, and is present before fertilisation. Normally, without
any extrenal treatment, this code disappears from the egg after
fertilisation. If the egg is subjected to a physical shock, such as a
pressure increase, or a temperature spike, or even just a good
shaking, this prevents the code from being ejected. This also occurs
in the wild, and is possibly a natural mechanism to prevent damaged
eggs being viable.

There is no genetic modification as such, no genes have been changed
or produced, but the number of chormosomes has been increased because
one female set was not lost after fertilisation. The egg now has
three sets of genetic information, instead of two.

Triploid fish grow and develop more or less normally, ( with some
exceptions, see below), but when they try to reproduce, the three sets
of genetic code can not divide properly, and no viable eggs or sperm
are produced.

This is also why at some fisheries, fish my be caught which are full
of eggs and milt! In a lot of cases this is reabsorbed by the fish,
given time, and in many other cases the fish simply die.

As described above, this is really only a basic and simplified model
of the process.Many species are naturally possessed of multiple
identical chromosome sets, "tetraploid" ( four sets),
"hexaploid" ( six sets), heptaploid ( seven sets) etc. When more than
diploid, the term usid is normally "polyploid".

In order to ensure triploidy, the exact point, type, and degree of
shocking is of paramount importance. Too small a shock and triploidy
does not occur, if the timing is wrong triploidy will also not occur.
Too much shock, and the eggs may be killed.

Furthermore, in any batch of eggs so treated, the incidence of
triploidy is never more than about 90% maximum,. and may be
considerably less. farmers have to inspect the fish carefully in
order to remove any hen fish, before these are stocked. Even so, any
particular batch of mature "triploids", may contain a few fertile
fish.

In order to ensure continued viability of a species in the wild, there
must be a sufficient number of that species in existence, and there
must also be sufficient genetic diversity to ensure their survival. A
few fertile hen fish in a particular enclosed water, are not
considered to be a major danger, but this is not to say that they will
not be!

Many of the original rainbow trout imported to the UK and elsewhere,
came form original Steelhead strins, most especially Shasta river
steelhead. This explains their genetically programmed propensity for
running to sea given the opportunity. There are a couple of places in
the UK, most notably the Wye, where rainbows breed natually and are a
vibale population. There are a couple of other less well know places,
which I don´t want to mention here. There are also a few places in
Europe where small natural populations have established themselves,
including a few still relatively small populations of sea-going fish.
Mainly in the Baltic region.

Increasingly large numbers of rainbows are caught in the Baltic sea
every year, and although the vast majority of these fish are escaped
triploids, there is a small percentage of fish which return to various
rivers and spawn.

It is often stated that triploid fish are stocked because of their
better growth rates. This is not the case. Better growth rates in
the majority of rainbow stock trout have been selected for over a
period of time. Fish with high growth rates are selected as parents,
their progeny is also selected, and so on. Of course, selecting for
certain traits may also produce other problems, and it does!

Basically all the fish produced in Europe for stocking purposes are
selectively bred fast growing fish reared to a certain size using
fishmeal.

( Extract and link)

QUOTE

What Is Fishmeal

Fishmeal is a generic term for a nutrient-rich feed ingredient used
primarily in diets for domestic animals, sometimes used as a high-
quality organic fertilizer. Fishmeal can be made from almost any type
of seafood but is generally manufactured from wild-caught, small
marine fish that contain a high percentage of bones and oil, and
usually deemed not suitable for direct human consumption. These fishes
are considered 'industrial' since most of them are caught for the sole
purpose of fishmeal and fish oil production. A small percentage of
fishmeal is rendered from the by-catch of other fisheries, and by-
products or trimmings created during processing (e.g., fish filleting
and cannery operations) of various seafood products destined for
direct human consumption.

UNQUOTE

http://www.thefishsite.com/articles/...-fish-meal-in-...

This has extremely unfortunate, and in many places disastrous effects
on the marine environment, as vast quantities of wild bait fish are
used to produce the fishmeal.

The stocked fish, assuming good water and feed conditions, continue to
grow at rapid rates, and even after a fairly short time may at least
outwardly be almost indistinguishable from normal wild fish. But, as
they are the product of extreme selection from a limited gene pool,
manipulation, and intensive rearing, they do not possess many of the
faculties or instincts of wild fish.

In the meantime, in order to supply the continuous demand for stocking
and other purposes on the European markets, and especially the UK
market which is one of the largest, fish eggs are imported form a
number of places. This is also because fish from different areas spawn
at different times of year. Although a large number of producers spawn
fish artificially all the year round from their initial brood stock,
large quantities of eggs are now imported from Denmark and South
Africa. Some eggs also come from America, Canada, Iceland and even
Australia, among others.

Although extremely controlled by the government, many people feel this
is a recipe for disaster just waiting to happen.

From the hatcheries, they are grown on to the size required by the

waters wishing to stock them, once again using large quantities of
fish meal obtained form wild marine protein, and also using intensive
rearing methods involving the heavy use of various drugs and
chemicals which are essentila to any intensive rearing environment, in
order to prevent or control disease and parasites. Most fish are also
fed added colouring agents to make their flesh colour more attractive
to the eventual consumers.

Once actually at the fisheries concerned, stocking policies vary. Some
waters may stock large contingents of fish in one go, often at the end
of winter. Other fisheries may have large holding ponds in which they
continue to feed the fish until required for "topping up" the water
with fish. Others obtain their fish form special holding farms, which
specialise in supplying stock fish for this purpose.

TL
MC

"As a few of people asked me about this"
People without access to Google it would appear. Or maby fictional
people? I'de bet a few six packs you couldn't come up with real names
if you were rendered off to a secret CIA prison and interogated for
six months.

On Sun, 16 Sep 2007 11:13:42 -0700, Mike
wrote:

On 16 Sep, 19:48, Dave LaCourse wrote:
George?

I thought your heart gave out, old man. Welcome back. I fished with
your rod the other day. It doesn't compare to my other boos, but I'm
glad to have it. My best to Gladys.

The Pirate

**** off Lacourse, if you have nothing constructive to contribute, you
should keep your mouth shut. You just finished making a complete ****
of yourself, and nobody wants to see a repeat. You can´t win a
****ing match anyway, your dick doesn´t work properly any more, and
that also seems to have affected your brain.

MC

Ok, Ken. You were right. Push the button or twist the knob... it
matters not. Too easy. But, he does remind me of George.

Davie