Friday, October 05, 2012

Thesis: are the Numbers lower?

Back to the infamous numbers.

I assume that you're familiar with the Clarke paper.
In essence, it stipulates that more than 10 years ago, the fin trade was processing the fins of approx 40 million Sharks, give or take. Clarke herself has since speculated that the fin trade may have shrunk.

This brand new thesis appears to confirm her hunch.
Here's the relevant statement,  hidden at the bottom of page 56ff.

3.3.1. Best Catch estimates for Sharks and mean wet fin to body weight ratios

Based on BCEs, the total estimated global yearly catch for 200-2009 was 571,485 ± 114,297 t, of which 450,517 ± 90,103 t was from the EEZs of various maritime countries and 120,968 ± 24,193 t was from the High Seas.

3.3.2.  Estimation of traded dry fin weight using the Monte Carlo method

The model predicts that the mean potential weight of dried fins produced from global shark catch was 7795 t per year in the 2000s

This compares to Clarke's original estimate of 10,600 t of dry fins (that she then extrapolated into number of Sharks), this with the caveat that the new numbers could be too low due to non- and under-reporting, and that they could in fact be "similar" to those by Clarke.

Is this good or bad news for Sharks?
The hope would be that these lower numbers reflect better global protection measures - alas, like the author, I fear that the reported decline of Shark catches since 2003 is a reflection of the dramatic decline of Shark stocks due to overfishing.

Anyway, there you have it.
This is the latest credible research -  and I'm sure that if you are a regular reader of this blog, you understand.

H/T: Shark Year

No comments: