Hello all
There's no suggestion from me that we cull whales to protect seabirds so some of you, please settle down, its OK. Nevertheless, it is a fact that
seabirds that eat Krill have enjoyed much less food competition during the past whale-harvesting century than is now the case.
Moreover, it is probable that the more food (Krill) available during that period, helped raise some seabird populations above a typical level, in a
manner more recognised as the good times in a boom/bust cycle. Changing Krill predator feeding dynamics will have ecological consequences and this
includes a potentially negative impact on krill eating Seabirds.
As others have suggested, the decline of Krill is likely to be caused by various factors. The claim of 80% decline of Krill due to climate change is
nonsense and is totally alarmist. If it is true, the optimist should rejoice because the surviving 20% are clearly immune to climate change and will
breed.
Ian May
St Helens, Tasmania
Tim Jones wrote:
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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