Friday, November 20, 2009

California Fisheries Health

In the Science Magazine article Rebuilding Global Fisheries (July 2009), Boris Worm, Ray Hilborn et al conclude:
  1. California and New Zealand have the least over-exploited fisheries in the world.
  2. Existing fisheries management tools (e.g., catch limits) are sufficient to rebuild these fisheries without MPAs.
  3. Closure via marine protected areas will result in increased abundance of species with low mobility, rather than the larval dispersal panacea touted by MLPA.
Here's a video synopsis of the study.

Ray Hilborn:  “Much of the motivation for the MLPA was concern about the state of the groundfish stocks – there is clear evidence that these can be rebuilt without MPAs resulting from the MLPA that have only recently begun to be implemented.”  ... “The benefits of the MPAs established under the MLPA will be primarily to have some areas of high abundance of species with limited mobility.”

This is not the first time that Dr. Hilborn has criticized the MLPA process. In 2006, Hilborn and others reviewed the MLPA model for size and spacing of MPAs and found: “It appears to us that those prescriptions were pulled out of the air, based on intuitive reasoning.”

Click the graphic for the dataset from the study:

What is most interesting about this study is that it brings together for the first time two scientific perspectives: 

"In large part, the Worm-Hilborn clash reflects the different worldviews of the two disciplines. Fisheries scientists see marine ecosystems as a resource to be used, whereas marine ecologists usually envision pristine, unfished habitats as the ideal. 

"The two fields also tend to rely on different types of data. In their 2006 Science paper, Worm and his co-authors were trying to look at the global impacts of marine biodiversity loss. For that, they had to rely on the most comprehensive kind of data available: the tonnages that countries report are caught. Fisheries scientists, by contrast, tend to look at individual stocks of fish and typically use sparser data gathered by scientific means; they consider catch reports unreliable."

D├ętente in the Fisheries War, 10 April 2009 Volume 324 Science Magazine

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