DNA fingerprinting shows marine protected areas benefit fisheries

The first conclusive evidence that no-take protected areas can help restock exploited fish populations on neighbouring reefs was presented at the International Coral Reef Symposium (ICRS) yesterday. The findings are expected to help resolve a long-running debate worldwide about whether areas closed to all forms of fishing help replenish fish numbers outside the marine protected areas (MPAs).

“Using DNA fingerprinting technology, we now can clearly show that the benefits of MPAs spread beyond reserve boundaries, providing a baby bonus to fisheries,” said Geoff Jones, from the ARC Centre of Excellence for Coral Reef Studies (CoECRS) and James Cook University, who led the study.

ICRS, which is held every four years, is a global coral reef conference and a hotbed of the latest advances in coral reef science. The research and findings presented at ICRS2012 are fundamental in informing international and national policies and the sustainable use of coral reefs globally.

Jones presented his team’s findings as part of a media briefing on fish larval dispersal and the connectivity between reefs. He was joined by Leanne Fernandes, Director and Principal Consultant, Marine and Coastal Resource Management, Earth to Ocean; Stephen D Simpson, Marine Biologist and NERC KE Fellow, School of Biological Sciences, University of Bristol; and Bob Warner, Professor of Marine Biology at the University of California, Santa Barbara. A full video of the briefing, with each panellist’s discussion of the current science presented at ICRS and management applications of fish larval research, is available online.

The groundbreaking study was carried out in the Keppel Island group on Australia’s Great Barrier Reef by researchers from CoECRS, in conjunction with other leading research institutions.

“The implications for local fishing communities around the world are huge,” said Fernandes, who was the manager of the Representative Areas Program that established one-third of the Great Barrier Reef as no-take protected areas. “It’s never easy to protect areas from fishing because, so often, the fished areas are very important for local communities for food, livelihoods and lifestyles. So fishermen need to know for sure it will work.”

Fernandes said that Jones’s research also shows that MPAs can be effective on small scales, which has implications worldwide. For many communities, particularly those in the developing world that depend on small areas of reef for food and income, there are limited options for closing areas to fishing.

“The MPAs weren’t tens of kilometres across. Some were about 2 km across or even 800 m across, and they still worked,” she said. “This is great news for local fishing communities around the world because protecting areas about this size might be possible for them; protecting really big areas is just too hard.”

Using DNA samples, the team of scientists tracked the dispersal pathways of juvenile coral trout and stripey snappers larvae from MPAs in the Keppel Island group. They found that a very large proportion of juveniles, 65%, settled in nearby areas that are open to fishing. Most of the baby fish settled within 1-5 km of reserves but a significant proportion dispersed 10 km or more to find a new home.

In addition, the study found that the six marine reserves, which cover only 28% of the total reef area of the Keppels, had generated 50% of the total juvenile fish, both inside and outside of the reserves. “So 28% of the area protected equals 50% of the baby fish produced. This means there would have been a lot less fish if the no-take areas weren’t there,” Fernandes said.

Warner said that research into fish larvae behaviour is tremendously important to developing successful management approaches. Fish larvae, which are microscopic fish babies, are normally dispersed in the open ocean after they are born, living for days or weeks before the lucky survivors make it back a reef.

“This poses immense problems for management. How do you manage fish populations if the young produced are scattered out to sea like dandelion puffs drifting in the wind?” he said. But Jones has addressed this critical issue by showing that these fish babies do return to their home reefs, which means that local actions to protect fish can have direct local benefits, he said.

Simpson added that recent research has shown that fish larvae have highly developed senses, included smell and hearing, and can actively swim back to their home reefs. But that means the reef habitat and adult fish populations need to be intact for them to find their way home. That’s exactly what MPAs can provide, with spillover benefits for neighbouring reefs.

“This research is the strongest support for management strategies that adopt marine protected areas as a fundamental tool for sustaining fish populations,” Simpson said.

The paper ‘Larval Export From Marine Reserves and the Recruitment Benefit for Fish and Fisheries’ appears in the May online issue of Current Biology.