All,
I was lucky enough to travel to the Antarctic this January. There were lectures
on board ship regarding everything from explorers to geology to wildlife, and
there was a very informative one about krill. The decline in krill probably has
nothing whatsoever to do with predators. I am no scientist, but my
understanding is that it is likely due to:
- decrease in ice in key areas due to climate change, although large areas of
the Antarctic may be getting colder, with some increasing in temperature
- the invasion of Salp - an animal which is numerous like krill and is
gradually displacing it but has no known role in the upward food chain
- ocean acidifcation due to fossil fuel absorbtion - even immediate cessation
would take time to reverse the acidification
- possible overharvesting by humans. Certain countries have signed on to a
convention which limits krill harvesting to a very sustainable level but there
is much which goes on illicitly. However, krill is difficult to process after
harvest, so it is not hugely economically attractive and the amount of trade
which goes on may not be sufficient to be having a serious effect.
These things may be right or wrong but certainly a fair bit seemed empirically
and scientifically based.
I doubt those nasty whales have much to do with it given that there were a
thousand times as many in the Antarctic a hundred years ago....
The seabird declines are also probably much more due to increasing human
pressures (including the loss of krill) while we are carefully protecting
whales (at least most countries are).
When all is said and done, whatever nature's imbalances and competition for
resources are, it all comes down to one species - homo sapiens.
Cheers
Tim
> Date: Wed, 13 Apr 2011 06:32:52 -0700
> From:
> To: ;
> CC:
> Subject: Re: [Birding-Aus] Antarctic penguins losing to climate change
> through 80% krill decline
>
> Any details? Which "pelagic sea birds"? Which "whales"? Species? Numbers?
> Rather than a terribly superficial statement?
>
> ----------------
> Nikolas Haass
>
> Sydney, NSW
>
>
> ________________________________
> From: Ian May <>
> To: Laurie Knight <>
> Cc: Birding Aus <>
> Sent: Wednesday, April 13, 2011 6:35 PM
> Subject: Re: [Birding-Aus] Antarctic penguins losing to climate change
> through 80% krill decline
>
> Very unlikely scenario.
>
> Rather than negative climate impacts or human fishing scenarios causing an
> 80% decline of Krill, it is more likely that the massive expansion of whale
> populations are depleting the Krill biomass.
>
> We are observing pelagic sea bird declines and there is a correlation where
> whale populations are increasing.
>
> Ian May
>
>
>
>
>
> Laurie Knight wrote:
>
> > see http://news.mongabay.com/2011/0411-hance_penguin_krill.html
> > http://www.ipsnews.net/news.asp?idnews=55223
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