Innovative DNA-fingerprinting of fish

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 today (July 12).

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.

Jones presented his team’s findings as part of a media briefing at the International Coral Reef Symposium (ICRS) in Cairns on fish larval dispersal and the connectivity between reefs entitled "Reef Connections".

Held every four years, the International Coral Reef Symposium is the premier 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.

A full video of the briefing, with each panelist’s discussion of the current science presented at ICRS and management applications of fish larval research, is available online at www.icrs2012mediaportal.com.

The study was carried out in the Keppel Island group on the Great Barrier Reef by researchers from the ARC Centre of Excellence for Coral Reef Studies (CoECRS), in conjunction with other leading research institutions.

"The implications for local fishing communities around the world are huge," said Leanne Fernandes, who was the manager of the Representative Areas Program in Australia 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’ research also shows that MPAs can be effective on small scales, which has implications worldwide. For many communities, particularly 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 two kilometres cross or even 800 meters 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 snapper larvae from MPAs in the Keppel island group. They found that a very large proportion of juveniles -- 65 per cent -- settled in nearby areas that are open to fishing. Most of the baby fish settled within one to five kilometres of reserves but a significant proportion dispersed 10 kilometres or more to find a new home.

In addition, the study found that the six marine reserves, which cover only 28 per cent of the total reef area of the Keppels, had generated 50 per cent of the total juvenile fish, both inside and outside of the reserves. "So 28 per cent of the area protected equals 50 per cent 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.

Team member Prof. Bob Warner said that research into fish larvae behavior is tremendously important to developing successful management approaches. Fish larvae, which are microscopic fish babies, normally are 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.

Stephen 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 neighboring 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.