Beel den Stormer Presents the Only Fishery Blog You Need

Fish, Fisheries and Queryomics

PEW Environmental Group Makes a Bad Call

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Three days after a Pacific bluefin tuna sold for $1.76 million at auction in Tokyo, the Pew Environment Group (PEG) revealed “evidence” that the Pacific bluefin tuna population had fallen by 96.4 per cent from unfished levels, due to decades of overfishing.

Beel is sympathetic to charges of overexploitation, but Beel has examined the source of PEG’s allegations.  They are dead wrong. Look for yourself at the study they cite.

The report cited shows (Figure 4) that biomass of spawning tuna has declined. True, but there is evidence of a cyclical pattern PEG’s analysis did not accomodate. Nevertheless, there is a downward trend- by about 66%.   Recuitment of new fish to the fishery (Figure 5)- shows no change- this is easily seen. Spawning biomass, Figure 6, shows about a 50% reduction. Mortality due to fishing (Figure 7) shows about a 70%  reduction. In the end, these compensate.  Less death, less need for birth.  Period. This is math from the ancient Greeks.

All told, Beel’s call:  a fluctuating stock, maybe on the slight downhill side of things, but nowhere near a catostophe. No one this side of a lunatic is going to come up with a claim that the fishery has decreased by 96%.  Word.

Beel really expected to see a worst-case senario.  The data are clear, this stock is problematic, but there is no evidence of severe overfishing.

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This entry was posted on January 10, 2013 by in Commentary, Statistics and tagged .
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