Friday, August 7, 2009

Twisting the Science

By Bruce Steele & Diane Pleschner-Steele

It has come to our attention that certain organizations and individuals appear to be twisting or misrepresenting data presented in the recent Worm, Hilborn et al paper, Rebuilding Global Fisheries, that appeared in the July 31 issue of Science magazine.

We've included a few excerpts from the paper to provide a balanced view of its findings:

• reducing exploitation rates to u [exploitation rate] = 0.25 is predicted to rebuild total biomass, increase average body size, and strongly reduce species collapse with little loss in long-term yield [Fig. 2]...

• Since the 1990s, Iceland, Newfoundland-Labrador, the Northeast US shelf, the Southeast Australian shelf and California Current ecosystems have shown substantial declines in fishing pressure such that they are now at or below the modeled uMMSY [multi-species maximum sustainable yield exploitation rate]. However, only in the California Current and in New Zealand are current exploitation rates predicted to achieve a conservation target of less than 10% of stocks collapsed [Fig. 3A]

• Diverse management tools have helped to achieve reductions in exploitation rates [Table 1]. The most commonly used tools overall are gear restrictions, closed areas, and a reduction of fishing capacity, followed by reductions in total allowable catch and catch shares. Reductions in fishing capacity and allowable catch directly reduce the exploitation rate of target species by limiting catches...

We emphasize that the feasibility and value of different management tools depend heavily on local characteristics of the fisheries, ecosystem and governance system. ... A combination of diverse tools, such as catch restrictions, gear modifications and closed areas, is typically required to meet both fisheries and conservation objectives.

• Some of the most spectacular rebuilding efforts, such as those undertaken in California... have involved bold experimentation with closed areas, gear and effort restrictions, and new approaches to catch allocation and enforcement.

Commenting on the paper, Dr. Hilborn made the following statement:

“The analysis presented in our Science paper shows that the California Current ecosystem has the lowest exploitation rates of any place we examined in the world. The drastic reductions in harvest have been designed to rebuild the overexploited rockfish stocks. At present the community of groundfish is now at about 60% of its unfished biomass, far above the 30-40% level target for maximum sustained yield. 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.”

- Ray Hilborn, School of Aquatic and Fishery Sciences, University of Washington

Both my wife Diane and I view MPAs as one tool in a diverse resource management tool kit that can provide ecosystem benefits to sedentary stocks and protect unique habitats in a relatively untouched state [side-stepping the water quality issue]. We have always advocated for best available science and have strived to achieve it in the sea urchin and wetfish fisheries. However, in our minds 'best available science' also means acknowledging that California fisheries are managed conservatively -- with regulations even more restrictive now than MSY. As the bioeconomic models illustrate, in MSY and conservative management scenarios there is a direct trade-off between larger MPAs and larger socio-economic impacts for insignificant gain in conservation benefits.

We disagree with the size and spacing formula laid down by the SAT, as it is based on scorched-earth assumptions that are not valid in California [and many on the current and NCC SAT teams have expressed similar reservations]. Nevertheless, we will continue to work proactively within the MLPA process to achieve an MPA network in southern CA that meets the SAT guidelines to the extent possible and also minimizes economic pain to fishing communities to the greatest extent possible.

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