November 14, 2012
Numbers Of Overfished Tuna Could Improve With Pacific Fishing Zones
University of Hawaii “ SOEST
Marine zoning in the Pacific Ocean, in combination with other measures, could significantly improve numbers of heavily overfished bigeye tuna and improve local economies, a fish modelling study has found.
- restrict longline fishing in tuna-spawning areas
- manage the use of fish-aggregating devices (e.g. moored or drifting buoys which attract fish) in purse-seine areas.
"We found that simply closing areas off to fishing doesn't work, because the boats just move their operations to neighbouring zones and fish even harder. It's going to need a combination of approaches," he says.
"The model will help people evaluate alternative policies to manage tropical tuna fisheries. Our predictions can help countries estimate how effective conservation measures might be, relative to any economic effects, and tailor measures to suit their goals. The advantage of this approach is that effects can be estimated locally, as well as for the stock as a whole."
Half the current bigeye tuna catch is by longline, which targets high-value tuna sold as fresh fish. These fish command a market premium and sell for over $10 per kilogram.
The other half is caught in purse-seine nets as incidental bycatch when aiming to catch skipjack tuna. These juvenile bigeye tuna are sold to the canning industry for $1.70 per kilogram.
Dr Sibert says the study calls for a complete economic valuation of the Western Central Pacific Ocean (WCPO) tuna fishery.
He says the most effective conservation measures are those "which protect fish throughout their lifetime."
Rebuilding the bigeye-tuna stock will take at least 15 years, and will be affected by any climate changes the ecosystems experience.
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