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Thoughts on COTS - commercial harvest?

Discussion in 'Ocean Conservation' started by JasmineNeedsGills, Jun 7, 2020.

Could we harvest Crown-of-Thorns commercially to reduce the pressures on reef systems?

  1. Yes! Crush 'em up and let their worthless corpses fertalise the land!

    0 vote(s)
  2. Nope.... their toxins shall doom us all!

    0 vote(s)
  1. JasmineNeedsGills

    JasmineNeedsGills Contributor

    Sitting at home with nothing to do, as is the tradition these days, left me some time to daydream about coral reefs, and was reading up on some of the problem Crown-of-Thorns starfish have been causing in the Cook Islands, as opposed to their usual passtime of killing the GBR (Crown of Thorns Starfish, COTS, Coral Predators Killing Coral Reefs)

    COTS are a constant menace but it seems they occasionally have population explosions once their density in any area reaches a critical mass, especially if their predators are absent (as is the case on the GBR, where the Giant Triton is rare). In any case Tritons feed so slowly that although their scent repels COTS from an area, it doesn’t reduce their overall numbers.

    The Aussies have gone so far as to build COTS killing robots (Killer robots unleashed to tackle coral-eating starfish epidemic) but it’s hard to see funding for this lasting in the long term, and again not in a ay that can make a long term impact.

    This leads me to another idea. The industrialised mass commercial fishing, as we know, is great at wiping out vast numbers of fish, even when those fish are not destined for the dinner plate, i.e. many fish are farmed to turn into meal for other animals or crops. So, rather than than funding localised culls of the Crown-of-Thorns, or killer robots to stab them one by one… could it be possible to fund research into finding a marketable use for them, to encourage commercial harvesting?

    While COTS bodies are largely water, I imagine they may well contain some use on a commercial basis, sufficient one hopes that with initial help from NGO/public funds to incubate the industry, that in the long term it will take off and scale up by itself.

    There’s two possibilities I can think of.

    1. Agricultural fertilizer.I dug up an old NOAA report from the late 40s which conducted some experiments to this end, and found favourable results, with some caveats about the cost and challenges of processing, but didn’t make any specific mention of COTS. (https://spo.nmfs.noaa.gov/sites/default/files/pdf-content/mfr1063.pdf) - Given that in the case of the GBR there is significant agricultural activity very nearby that relies heavily on fertailiser (the QLD sugar plantations) then this seems like it could be a good solution.

    1. Fish meal. Though venomous, species to pray upon the COTS, and with processing I would guess it could be rendered into low level feedstock for fish farms or similar. The NOAA report makes mention of this being done with other species for use in poultry feed. There’s not as much local demand for this, but if rendering could be performed at a nearby port where the fish could be landed (say Cairns, Townsville or Mackay) then the finished product (of greater value and less volume) could be transported onward to a final market quite economically by rail.

    Potential problems.

    1. COTS populations are highly variable, occasionally reaching “plague” levels but then dropping significantly. That makes it hard for any business model that relies solely on the COTS.

    2. COTS can be hard to harvest, as they mainly feed at night, and often shelter under overhangs and in concealed places during the day. The drone technology currently in early/prototype stages could be modified for use in harvesting, but would need to become both much cheaper and more efficient to do so. One possible solution here would be developing a modification kit for an “off the shelf” underwater drone rather than a whole unit built from scratch.

    Just some random quarantine thoughts - would love to hear of any projects that have been working along these lines, and if not one others thoughts are. If no organisation has been going down this road, are there any particular reasons why not?
    Yawana-Dive likes this.

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