The 'famous scientist' Walter Starck has gone to some effort to criticise fisheries management on the Great Barrier Reef by comparing catch per unit area, insisting that the fishing is being overly restricted. This is like a farmer in arid lands insisting he should be able to have the same stocking rates as one on the east coast.
freediver wrote on Jul 24
th, 2010 at 8:52am:
fishfinder wrote on Jul 24
th, 2010 at 2:15am:
I would have thought the important point would be not that CPUA is 100X lower on the GBR coral reefs than other reefs with different oceanography, biology and fishing methods etc.- but what CPUA can the GBR handle? We know quite a lot about the oceanography and biology of the GBR and fishing methods employed there. I don't think any other scientists have suggested ratcheting up the fishing pressure to that extent and it seems a pretty radical course of action based on a simple comparison and a lone voice.
I'm no expert but I would have thought not all coral reef fisheries are the same. Temperate fisheries are not.
Where I'm living in WA the entire demersal scalefish catch (of over 15 species) was ~1500t in an . It has been cut this year to ~750t to avoid 'high risk' of collapse of those fisheries. This fishery is spread over ~1000km of coastline. Just one of those species, Pink Snapper, in just one fishery zone in New Zealand - over about 100km of coastline - has an allowable catch of 4500t that is considered a sustainable yield. In other words one species in a fishery area a tenth of the size can produce six times more fish than all the fish in 1000km of coastline in Western Australia.
To me, this suggests that fishery productivity varies widely.
Exactly. You don't have to be an expert to figure that one out. Most people would laugh if a 'scientist' compared farm stocking rates in an arid region with those in a wet region and suggested this is a good way to judge whether stocking rates should be increased or decreased. It would get even more ludicrous if different animals from different parts of the food chain were being harvested and it was strongly impacted by size effects an inflows from surrounding regions.
Yet this is what Walter does with the oceans. He and his devoted followers accept the absurd simplification that because they are both called a 'reef' it is reasonable to expect the same level of productivity. His analysis is based on the equivalent of ignorance of the difference between a desert and a jungle.
I suppose you couldn't expect much more from a self described "pioneer in the scientific investigation of coral reefs" who does not have a single scientific publication in a peer reviewed journal.
PJ responded by claiming that the evidence suggests that the Great Barrier Reef is more productive, even though the evidence being presented was of lower yields.
pjb05 wrote on Jul 24
th, 2010 at 9:43am:
Also there is no evidence the GBR is less productive than these reefs. Actually it's probably more productive.
He then went on to suggest that because we target fish higher up the food chain than at the comparison sites, the catch rates should be higher. This is like saying you should be able to harvest more lions than you could buffalo on the African plains.
pjb05 wrote on Jul 24
th, 2010 at 1:43pm:
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Quote:The fact that we don't target the herbivours like the susbsistence fishermen of the South Pacific is a good thing, given their role in reef ecology.
2) Given that herbivores are lower on the food chain, they can support higher catch rates, so it is definitely a bad thing if you use this as a benchmark for judging the sustainability of catch rates for a fishery dominated by higher level carnivores.
The evidence above suggests the contrary. And not all fish lower in the food chain are herbivours. Even though genuine scientists balked at making the same conclusions as Walter when they made similar comparisons, and actually advised against it, PJ insits that they would have in this case:
Quote:They weren't making comparisons with the GBR were they. If they were they may have well drawn the same conclusions as Walter.
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Walter's 'paper' comparing catch rates (Read 3586 times)
