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Antarctic krill: Key food source moves south

January 22, 2019
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By Paul Homewood

Today’s climate scare comes from the BBC:

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A keystone prey species in the Southern Ocean is retreating towards the Antarctic because of climate change.

Krill are small, shrimp-like creatures that swarm in vast numbers and form a major part of the diets of whales, penguins, seabirds, seals and fish.

Scientists say warming conditions in recent decades have led to the krill contracting poleward.

If the shift is maintained, it will have negative ecosystem impacts, they warn.

Already there is some evidence that macaroni penguins and fur seals may be finding it harder to get enough of the krill to support their populations.

"Our results suggest that over the past 40 years, the amount of krill has, on average, gone down, and also the location of the krill has contracted to much less of the habitat. That suggests all these other animals that eat krill will face much more intense competition with each other for this important food resource," Simeon Hill from the British Antarctic Survey told BBC News.

It focuses on the Scotia Sea and the Antarctic Peninsula – the places where the crustaceans are most abundant.

Scientists have been gathering data in these areas since the 1920s.

Initially, krill catches were recorded to understand the environmental consequences of commercial whaling, but the information has continued to be collected through to the present.

Dr Hill and colleagues say the change in the distribution and density of the crustaceans is a clear signal that emerges in the data from the late 1980s onwards.

It coincides with a phase change in a climate oscillation known as the Southern Annular Mode.

The SAM essentially describes the dominant pattern of pressure zones in the southern hemisphere outside of the tropics.

The mode’s switch in state in the late 80s produced warmer, cloudier, windier weather, and much less sea-ice in those areas where the krill had tended to congregate.

https://www.bbc.co.uk/news/science-environment-46953652

Note to the BBC – the Southern Annular Mode (SAM) has nothing whatsoever to do with climate change. Instead it is simply a natural climatic cycle, just as the PDO or AMO are.

New Zealand’s Environmental Reporting Series shows how the SAM has oscillated since the 1800s:

SAM-fig1-static

http://archive.stats.govt.nz/browse_for_stats/environment/environmental-reporting-series/environmental-indicators/Home/Atmosphere-and-climate/southern-annular-mode.aspx

The population of krill has been affected by other factors over the decades.

When commercial whaling was large scale in the early years of the 20thC, the population of krill would naturally have thrived.

Just at the time when whaling was ending, fishing for krill took off. According to this 2014 paper:

Fishing is the major industry in Antarctic waters. Hundreds of thousands of tons are landed each year. Antarctic krill (E. superba) support the largest fishery (Figures 5 and 6). In the 1970s, development of the commercial krill fishery was facilitated by heavy fishing subsidies in the USSR, which became the most important krill-fishing nation during the 1970s and the 1980s (Nicol and Foster, 2003).

https://academic.oup.com/icesjms/article/71/7/1934/666832

FAOSTAT show how the harvest of Antarctic krill grew from a figure of 4t in 1961 to over 500,000t. Even though harvest dropped back in the 1990s, the damage had already been done.

 chart-1

http://www.fao.org/fishery/species/3393/en

Most of the fishing takes place in the Scotia Sea, which this new study has identified as the main area of decline.

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https://www.nature.com/articles/s41558-018-0370-z.epdf?referrer_access_token=p0Y9my7yPk20M2v2UcWTt9RgN0jAjWel9jnR3ZoTv0MBxinTLF4eJC0VduOthzvj0lw7ufoGLfGEdGOile2n1qc6U0jLx1hl1fgXDv61cUj6ywiPvZVxCnJh1gwWFdprLUVOOHMhWqDxPri4LZ_1VRxP-kwKPkDq1ZGuVwxuSkAz30qIcX4UFrvThwOZcByyGS25ukJ9ctpqXNWkljeI8ylMqjP-8M8cWIJUmOVbYKw%3D&tracking_referrer=www.bbc.co.uk

According to the BBC article:

Margaret McBride, from the Norwegian Institute of Marine Research in Bergen, has written a comment article on the research in the same edition of Nature Climate Change.

She said models had predicted that krill would shift southwards in the future, whereas the new research suggested this contraction was already under way.

"It offers a profoundly adverse, but highly plausible, endgame for Antarctic krill that has serious implications for both the Southern Ocean food web and sustainable management of fisheries targeting this species," she wrote

However, although the actual study makes vague warnings about what a warmer climate might bring in future, it provides no evidence that global warming has had any effect on the current situation.

Indeed, on the contrary Southern Ocean SSTs have been dropping since 1980, and currently are below the long term mean.

14-southern-ssta

https://bobtisdale.wordpress.com/2016/11/08/october-2016-sea-surface-temperature-sst-anomaly-update/

http://climate4you.com/ 

It has also been claimed that krill are at risk from winter sea ice recedes. But as we know, winter sea ice extent has been gradually rising since 1979:

 

seaice.pl

seaice.pl

Antarctic krill E. superba. (a) Change in mean density of post-larval krill (ind. m−2) within the SW Atlantic sector (30–70°W) between 1976 and 2003. Based on the post-1976 dataset, there is a significant decline: log10(krill density) = 60.07 − 0.0294 (year); R2 = 31%, p = 0.007, n = 22 years (Source: modified from Atkinson et al., 2008; ©Inter-Research 2008). (b) Reported krill catches (in metric tonnes) in FAO Statistical Area 48, 1973 to 2011 (CCAMLR, 2010, 2011a) (source: Flores et al., 2012). (c) CCAMLR 2013 reported krill catches (source: http://www.ccamlr.org/en/fisheries/krill-fisheries).

https://nsidc.org/data/seaice_index/bist 

 

There is no evidence in this study to show that the population or distribution of Antarctic krill has been affected by global warming, or will be in future.

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10 Comments
  1. John Palmer permalink
    January 22, 2019 5:46 pm

    Goodness me, Paul…. how the Green Blob MSM must hate you!
    Whatever breathless new “scientific” scam they report, you just forensically dissect it and expose their incompetence and/or carelessness.

    • January 22, 2019 6:09 pm

      john,
      the MSM are neither incompetent or careless….but they are deceitful
      this has been going on for 30 yrs.

      It’s now got to the stage of …’it’s on the BBC therefore it’s probably untrue’.

  2. dennisambler permalink
    January 22, 2019 6:15 pm

    “Margaret McBride, from the Norwegian Institute of Marine Research in Bergen, has written a comment article on the research in the same edition of Nature Climate Change”.

    She didn’t mention Norway’s krill harvesting industry.

    https://www.undercurrentnews.com/2018/11/05/aker-biomarines-new-118m-state-of-the-art-vessel-set-for-next-antarctic-krill-fishing-season/

    “Krill is used in health products, food, flavourings, feed additives, pet food and aquarium feed – and is a key species in Antarctica’s eco-system, providing food for whales, penguins and seals”:

    Greenpeace report said Krill harvesting is a serious problem: https://www.theguardian.com/environment/2018/mar/13/krill-fishing-poses-serious-threat-to-antarctic-ecosystem-report-warns

    Others don’t think so:

    https://www.lowyinstitute.org/the-interpreter/calm-alarm-antarctic-krill-fishery

    • mwhite permalink
      January 22, 2019 6:32 pm

      First thing that entered my head, moved south or fished out?

  3. January 22, 2019 7:28 pm

    A few points:

    1) if the numbers given in wiki are any guide, then fisheries are not an important cause of population change (population estimated at 500 million tonnes, and fishing (human kind) at 100 thousand tonnes/yr). I had thought that fishing was more significant, but it seems not.

    2) reaching for my handy copy of “The Open Sea: the World of Plankton” by Alister Hardy (1956), (yes, really) I find that the daily ascent and descent of the krill enables them to maintain their geographical position. They travel north in the surface current by night and travel south by day in the reverse current. (Maybe this knowledge has been superseded).

    3) this kind of study worries me, not in fear for the krill or the mammals and birds they support, but because if such a study was done and did not find such a shift, it would not merit publication. I am not suggesting any impropriety of course. But just how much warmer is the Southern Ocean than 80 years ago? (I think it is a red herring to look at recent temperature anomalies).

    4) the productivity of the Southern Ocean is based upon sunlight (and nutrients that accumulate in the winter & presumably cycle). Therefore unless cloud levels have changed, productivity is the same now as in the 30s. This raises numerous questions, for example have there been shifts in phytoplankton communities, or have krill been displaced by salps (a kind of tunicate)?

    5) any effect on krill would have to be permanent for such shifts to maintain, because they multiply so fast that a depleted population in one year would be back to normal the following year unless the same perturbation was in place.

    Perhaps I should shut up, keep an open mind and read the paper…

  4. Bob Fernley-Jones permalink
    January 22, 2019 7:32 pm

    I sometimes wonder if the Japanese are covertly worried that the increasing whale population may lead to less krill, and are trying to do something about it

  5. Henning Nielsen permalink
    January 23, 2019 12:38 am

    But “Kill Krill” is an even better slogan than “Kill Bill”, irresistable it must be for the activists.

    Expect to hear shouts of “Krill Killer!” at the next COP meeting.

  6. January 23, 2019 3:20 am

    Thank you. The Zealots are happiest with the incomplete story

  7. Europeanonion permalink
    January 23, 2019 8:37 am

    How are the plankton levels? They might be a better indicator of change.

  8. saparonia permalink
    January 26, 2019 2:34 pm

    Thank you for your perseverance in dissecting the propaganda.

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