Closing off areas of the Pacific Ocean to bigeye-tuna fishing might not be the most effective conservation measure, a modelling study suggests.
Pacific populations of bigeye tuna (Thunnus obesus) are being threatened by both 'purse seine' fishing, which involves catching large schools of fish with nets, and longline fishing. This led authorities to close two areas to purse seine fishing in 2009, but the effects of these closures have never been evaluated. John Sibert at the University of Hawaii in Honolulu and his colleagues used a model of tuna population dynamics to simulate the effects of different fishery-management practices on tuna biomass.
The researchers found that closing high-seas enclaves in the western central Pacific Ocean to purse seine fishing had little effect on the fishes' biomass. Reducing longline fishing in spawning areas, and prohibiting the use of fish-aggregating devices that increase the incidental catch of bigeye tuna, seem to be more efficient ways of maintaining tuna populations.
Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1209468109 (2012)
For a longer story on this research, see http://go.nature.com/xuyljd