Australian Fish Moving Poleward

CSIRO researchers say there is striking evidence of tropical species moving south as sea temperatures rise quickly.

The scientists say large numbers of marine animals and plants are already dying off or migrating.

Can we stop pretending we aren’t sure anything is happening yet?

Comments:

  1. A nice illustration of your previous blogpost. I doubt very much that anyone at CSIRO said that the evidence was striking. The whole tenor of the fishy parts of the report is that evidence is scarce, patchy and anecdotal - a fisherman reports catching an exotic tuna off eastern Tasmania, that sort of thing.

    And did 'scientists say large numbers of marine animals and plants are already dying off or migrating'? They said that the ranges of some marine plants are slowly contracting. I suppose that might count as a die-off. But large numbers of Australia's marine mammals dying off or migrating? If you can find that in the report, you're better at skim-reading than I am (it's a very long report). Again, the main story is a scarcity of evidence. (The report has to bring in studies about Scotland and New Zealand to pad it out.) One 2004 study said that dugongs might temporarily occupy areas where water has warmed temporarily. A particular type of dolphin might have moved into a particular bay when its waters warmed. Blue whales might do something or other. Dying off? Permanent migration? Not that I can find.

    That's the journalism. How about the report itself? Does a sentence like the following really belong in something billed as an impartial scientific report?

    'We note with concern that some fishery status reports (e.g., Rowling et al. 2010) are still not considering climate change as an issue of significance.'

    (Rowling et al was a NSW govt report on commercial fish stocks. It was chiefly concerned with overfishing and - the horror! - didn't mention climate change at all. Incidentally, it included a section on the 'jackass morwong', a wonderful name that deserves wider application. Perhaps it could replace 'denier' or 'alarmist' or both.)

    I'm not saying, of course, that Australian marine life isn't reacting to warming waters and shifting currents or that it won't react more strongly in the future. It's just that the actual observations of reactions are far from striking.

  2. Adelady, would it be overly picky to point out that those are a different bunch of researchers or that corals aren't fish? Still, I'll concede that four coral species moving into a new area in the last 20 years is moderately striking.

    This looks dodgy, though:

    'Over the last ten years, researchers have observed dramatic increases in the number of tropical reef fish species appearing in the more temperate waters of the New South Wales coastline.'

    Dramatic? Here's what the new Report Card says about tropical coastal fish:

    'Increasing occurrence and persistence of recruits from tropical species in sub-tropical and temperate locations. Increased reports of tropical species in temperate locations.'

    But:

    'The confidence level is LOW for observed impacts on geographic ranges ... because there is limited evidence available to date and it is difficult to distinguish climate change effects from natural variation (e.g. El NiƱo).'

    Can limited evidence = dramatic? Especially when it can't be reliably tied to long-term climate change?

    The researchers who wrote that article know a lot more about this subject than I do but I smell overselling. (They were, after all, trying to recruit the public to a reporting programme.)

  3. Cripes! The report's website did say 'striking evidence' after all. It has been inaccessible at this end for the last few days but here's a googlecache:

    'Many new changes have been documented since the 2009 Report Card. There is now striking evidence of extensive southward movements of tropical fish and plankton species in southeast Australia, declines in abundance of temperate species, and the first signs of the effect of ocean acidification on marine species with shells.'

    I didn't see that the last time the website was working. Silly me.

  4. Thanks, mt.

    But ...

    Was the evidence striking? Was that welcome page perhaps written by a presso rather than a scientist? The bits of the report I read were, at best, equivocal.

    Hmmm. www.oceanclimatechange.org.au is now available again. So I suppose I should do more reading.

    Not in the mood. => The evidence *was* striking. I give up.


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