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

Sea Lice and Salmon
 

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.

Sea Lice and Salmon
 

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)

Sea Lice and Salmon
 

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

Sea Lice and Salmon
 

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.

Sea Lice and Salmon
 

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.

Sea Lice and Salmon
 

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

Sea Lice and Salmon
 

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

Sea Lice and Salmon
 

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

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

Sea Lice and Salmon
 

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

Sea Lice and Salmon
 

On 16 Dec, 07:10, Tim Lysyk wrote:

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


Just a question, because I don´t know anything about pink salmon. Do
all the pink salmon of a particular year return at the same time?

Just wondering because of the two year cycle you mentioned.

Sea Lice and Salmon
 

Oh, and just one other point. Does this mathematical model take
population viability levels into account? Or does it just show the
time to extinction?

I saw a model here which demonstrates that population viability levels
reach a critical point quite a while before actual extinction, but
this also accelerates the extinction. ( Hope that made sense?).

Unfortunately I don´t know what this model is called.

Sea Lice and Salmon
 

Just a question, because I don´t know anything about pink salmon. Do
all the pink salmon of a particular year return at the same time?

Just wondering because of the two year cycle you mentioned.

All I can find is that they spawn from late-June to Mid-October, but I
don't know if that is over a wide geographic area, or if the spawning
times are more restricted on individual rivers.

Tim Lysyk

Sea Lice and Salmon
 

"Mike" wrote in message
...

Just a question, because I don´t know anything about pink salmon. Do
all the pink salmon of a particular year return at the same time?

Just wondering because of the two year cycle you mentioned.

Pink Salmon (also commonly called Humpies because of the pronounced hump
that forms on spawning males) - the smallest of the PNW salmon species -
mature in 2 years (1 year at sea) and, unlike many other species of salmon,
do not have some portion of the population staying at sea for longer
periods. In many watersheds significant runs occur only every other year,
with very weak runs in the off years. i.e some watersheds have even # yr.
runs while others have odd # yr. runs, and at times for no apparent reason
the cycle of the runs within a given watershed may switch from odd yrs. to
even years (or vice versa) for no apparent reason. Fish from odd yr runs
and even year runs do not interbreed, though Humpies have been known to
cross with Chum salmon producing a sterile hybrid.


Bob Weinberger La Grande, OR

Sea Lice and Salmon
 

Mike wrote:
Oh, and just one other point. Does this mathematical model take
population viability levels into account? Or does it just show the
time to extinction?

I saw a model here which demonstrates that population viability levels
reach a critical point quite a while before actual extinction, but
this also accelerates the extinction. ( Hope that made sense?).

Unfortunately I don´t know what this model is called.

The Ricker model is mostly used to predict a time series of data, i.e.,
numbers at one time as a function of numbers at an earlier time. It
differs from the logistic model in that negative population growth can
occur at high numbers; it becomes quite a bit more stochastic, and even
chaotic.

The authors mainly used the Ricker model to estimate population rates of
change, then used a viability analysis to estimate extinction times.

Tim Lysyk

Sea Lice and Salmon
 

"Bob Weinberger" wrote in message
news:pe49j.1098$Vg1.56@trndny04...

In re-reading what I wrote , I believe that I didn't make it clear that,
though Pinks in a given watershed are PREDOMINANTLY either odd yr or even yr
spawners, there are runs every year within a watershed.

Bob Weinberger La Grande, OR

Sea Lice and Salmon
 

Bob Weinberger wrote:
"Bob Weinberger" wrote in message
news:pe49j.1098$Vg1.56@trndny04...

In re-reading what I wrote , I believe that I didn't make it clear that,
though Pinks in a given watershed are PREDOMINANTLY either odd yr or even yr
spawners, there are runs every year within a watershed.

Bob Weinberger La Grande, OR







If you want a detailed map to see where they are talking about, here is
a link below. It is a large PDF file, about 3 megs.

http://ilmbwww.gov.bc.ca/lup/lrmp/co.../broupa62m.PDF

Sea Lice and Salmon
 

OK. Thanks for the info.

TL
MC