A fish modeling study has found that marine zoning in the Pacific Ocean, in combination with other measures, could significantly improve numbers of heavily overfished big-eye tuna and improve local economies.
Scientists working at the University of Hawaiʻi at Mānoa, the Secretariat of the Pacific Community (SPC, Noumea, New Caledonia) and Collecte Localisation Satellites (CLS, Toulouse, France), have found that a network of marine zones in the Pacific Ocean could be a more effective conservation measure than simply closing relatively small areas to some types of fishing. These marine zones, where different fishing activities are allowed in different areas, may have significant and widespread benefits for big-eye tuna numbers.
Emeritus Professor John Sibert of the UH Mānoa Joint Institute of Marine and Atmospheric Research is one of four scientists leading the study.
After testing the effectiveness of a range of conservation measures with an ecosystem and fish population model, Sibert says the team found that the most effective measures were to:
- 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,” said Sibert. “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.”