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