I think increasing krill harvesting by humans will also play a role Ian!
On 23 January 2015 at 10:28, Ian May <
<>> wrote:
Thanks for your reply David.
Yes I think "prior to ma's assault on whales and other cetaceans"
the available food balance was probably of little concern
regarding population survival, but the problem as I see it, is
that now is a time when overall seabird numbers are artificially
increased due to the absence of significant feeding competition
from Cetaceans, and because of this, the entire seabird population
is now at much greater risk of a crash from starvation if impacts
on the same available food source are suddenly increased, as must
be the case now, not from Climate Change, but from Cetacean
feeding competition.
Most people with an agricultural background will be aware of what
happens to animals, both wildlife and domestic when severe drought
descends on the country. If my memory of J curve is correct, when
a population exceeds the carrying capacity of its food source,
there "will be" a significant population crash. After this
occurs, for species that have evolved to adapt to a boom bust
cycle, most of these populations will recover, but as you would be
aware, boom bust ecology is not how it is with seabirds and a
major crash may well go beyond the tipping point for many of them.
regards
Ian May
PO Box 110
St Helens, TAS 7216
------------------------------------------------------------------------
David Bishop wrote:
Dear Ian,
This sort of connectivity fascinates me. I cannot help but
ponder your question as it makes one wonder, if you are
correct, what were penguin numbers like prior to ma's assault
on whales and other cetaceans? Perhaps the krill population
was commensurately larger in those far off times?
David Bishop
P. O. Box 1234, Armidale, NSW 2350, Australia
M +61 412 737 297 <tel:%2B61%20412%20737%20297> Office +61 2
6771 5580 <tel:%2B61%202%206771%205580>
On 23 Jan 2015, at 9:10 am, Ian May
< <>
<
<>>> wrote:
H
Hello Laurie
Not wanting to upset "the believers", I cannot help but
wonder if these researchers ever considered that a decline
of Antarctic Krill could be caused by the exponential
increase of Cetaceans that has occurred over the past two
decades. Is it true that a current population estimate
of just one species, the humpback whale has now reached
80,000 individuals? About five years ago, the population
estimate at that time had increased to 35,000 animals?
See
http://en.wikipedia.org/wiki/List_of_cetaceans#Global_Population_Estimates
or http://whaleone.com.au/whale-facts/
As a part time researcher from a time nearing the end of
the commercial whaling era when it was rare to sight a
large whale in Australian waters, I occasionally pondered
the effects on the pelagic world from competition on the
basic marine food source impacted by the presence or
absence of Cetaceans.
My conclusion was that you cannot have your krill and eat
it too.
regards
Ian May
PO Box 110
St Helens, 7216
------------------------------------------------------------------------
Laurie Knight wrote:
The following study contrasts the fortunes of
Chinstrap and Gentoo Penguins
see
http://www.sciencedaily.com/releases/2015/01/150120121304.htm
Original study: MJ Polito, WZ Trivelpiece, WP
Patterson, NJ Karnovsky, CS Reiss, SD Emslie.
Contrasting specialist and generalist patterns
facilitate foraging niche partitioning in sympatric
populations of Pygoscelis penguins. Marine Ecology
Progress Series, 2015; 519: 221 DOI: 10.3354/meps11095
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