Sea Lice and Salmon

This time it is a Canadian population of salmon that is threatened.

http://news.bbc.co.uk/1/hi/sci/tech/7142053.stm

Tim Lysyk

On 16 Dec, 01:34, Tim Lysyk wrote:
This time it is a Canadian population of salmon that is threatened.

http://news.bbc.co.uk/1/hi/sci/tech/7142053.stm

Tim Lysyk

Actually a number of populations are threatened, and various sea trout
runs have more or less been eradicated in a number of places.
Unfortunately, it is quite impossible to convince the powers that be
of the desperate situation. There is too much money involved in this
type of aquaculture. The absolutely massive damage it is causing to
the environment on several fronts is simply not a consideration it
seems.

When the wild fish are wiped out, the farms will rule.

On Dec 16, 8:34 am, Tim Lysyk wrote:
This time it is a Canadian population of salmon that is threatened.

http://news.bbc.co.uk/1/hi/sci/tech/7142053.stm

Tim Lysyk

"Using a mathematical model of population growth rates, they show that
sea lice from industrial fish farms are reducing the numbers of wild
pink salmon - a Pacific salmon species - to the extent that the fish
could be locally extinct in eight years or less.

Dr Krkosek said the population growth rate was "severely depressed".

"It means that the probability of extinction is 100% and the only
question is how long it is going to take," he told BBC News. "

The 'probability of extinction' statement exposes that they are using
an exponential growth model, a la Malthus, while it is more likely a
logistic curve model. Logistic curves are self-correcting, although
all the mechanisms that decrease growth are not always known.

--riverman (off to create math Final exams, with his head in the
numbers)

On 16 Dec, 04:14, riverman wrote:
On Dec 16, 8:34 am, Tim Lysyk wrote:

This time it is a Canadian population of salmon that is threatened.

http://news.bbc.co.uk/1/hi/sci/tech/7142053.stm

Tim Lysyk

"Using a mathematical model of population growth rates, they show that
sea lice from industrial fish farms are reducing the numbers of wild
pink salmon - a Pacific salmon species - to the extent that the fish
could be locally extinct in eight years or less.

Dr Krkosek said the population growth rate was "severely depressed".

"It means that the probability of extinction is 100% and the only
question is how long it is going to take," he told BBC News. "

The 'probability of extinction' statement exposes that they are using
an exponential growth model, a la Malthus, while it is more likely a
logistic curve model. Logistic curves are self-correcting, although
all the mechanisms that decrease growth are not always known.

--riverman (off to create math Final exams, with his head in the
numbers)

Only necessary to know one growth decreasing mechanism here, the death
of the smolts caused by the sea lice.

The contamination is so great in systems affected by fish farms,
where before the advent of the farms it was zero, that the destruction
of the native fish is only a matter of time. Even if a few fish return
to spawn, their progeny can not survive the onslaught of the sea lice
when moving out to sea. The natural mechanisms which would normally
prevent total extinction (for instance, some fish overwinter, and do
not return to spawn each year, some may skip several years) have been
circumvented, and the runs are being destroyed at source.

The only possible solution would be to close the farms immediately,
and possibly use large scale measures to eradicate the massive numbers
of sea lice. The alternative is the total destruction of the salmon
run. This is also the more likely scenario, as neither government or
industry are prepared to take such warnings seriously, Preferring to
lie and prevaricate out of political and economic interest.

This will also affect far more than the salmon runs. Everything that
depends on those runs will also be severely affected.

In view of the ever weakening position of many anadromous fish at
various places, due to other factors. Fish farms destroying at source
will sound the death knell for many runs. This is so incredibly
foolhardy and short-sighted that it beggars belief. But still it is
done, for money.

MC

Also ironic, that the presence of a few sea lice on a fish caught in
freshwater were once greeted as a sign of fresh run healthy fish. Now,
they signal a dead one. Thanks to foolish tampering.

Mike wrote:
Also ironic, that the presence of a few sea lice on a fish caught in
freshwater were once greeted as a sign of fresh run healthy fish. Now,
they signal a dead one. Thanks to foolish tampering.

It's still that way some places -- no telling how long it will last.

--
Cut "to the chase" for my email address.

Tim Lysyk wrote:
This time it is a Canadian population of salmon that is threatened.

http://news.bbc.co.uk/1/hi/sci/tech/7142053.stm

Tim Lysyk

One of the many ironies of this story is that it only refers to
"Canadian salmon", ignoring the distinction that the wild salmon
threatened are Pacific salmon of the genus Oncorhynchus (O.
gorbuscha), while the farmed salmon causing the trouble are
Atlantic salmon (Salmo salar), fish that have no business in the
Pacific ocean to begin with.

Well, no business other than Business....

Still, the basic problem is that if you artificially increase the
population density of a species, you're going to increase
density-dependent transmission of parasites. Something to keep
in mind the next time you're tempted to buy salmon in the store
at such a "reasonable" price.... a price, in fact, lower than it
was 10-15 years ago, before coastal farming took off....

- JR

On 16 Dec, 06:19, JR wrote:
Tim Lysyk wrote:
This time it is a Canadian population of salmon that is threatened.

http://news.bbc.co.uk/1/hi/sci/tech/7142053.stm

Tim Lysyk

One of the many ironies of this story is that it only refers to
"Canadian salmon", ignoring the distinction that the wild salmon
threatened are Pacific salmon of the genus Oncorhynchus (O.
gorbuscha), while the farmed salmon causing the trouble are
Atlantic salmon (Salmo salar), fish that have no business in the
Pacific ocean to begin with.

Well, no business other than Business....

Still, the basic problem is that if you artificially increase the
population density of a species, you're going to increase
density-dependent transmission of parasites. Something to keep
in mind the next time you're tempted to buy salmon in the store
at such a "reasonable" price.... a price, in fact, lower than it
was 10-15 years ago, before coastal farming took off....

- JR

Very true. The stuff is being sold at dumping prices.

May be also be of interest;

http://www.salmonfarmmonitor.org/

http://www.wild-fishing-scotland.co....php?board=28.0

http://www.esa.org/science_resources...ues/issue8.php

http://www.esa.org/science_resources...ish/issue8.pdf

riverman wrote:

"Using a mathematical model of population growth rates, they show that
sea lice from industrial fish farms are reducing the numbers of wild
pink salmon - a Pacific salmon species - to the extent that the fish
could be locally extinct in eight years or less.

Dr Krkosek said the population growth rate was "severely depressed".

"It means that the probability of extinction is 100% and the only
question is how long it is going to take," he told BBC News. "

The 'probability of extinction' statement exposes that they are using
an exponential growth model, a la Malthus, while it is more likely a
logistic curve model. Logistic curves are self-correcting, although
all the mechanisms that decrease growth are not always known.

--riverman (off to create math Final exams, with his head in the
numbers)


Nope. They were using a Ricker model, modified for the two-year life
cycle of the pink salmon, which has a density dependent growth term in
it. They estimated rates of increase from an extensive data set, then
added a parasite induced mortality term estimated from years that salmon
populations were exposed to sea lice. The time to 99% extinction was
estimated from the population growth rates, and is about 4 years.

Tim Lysyk