Reserve Fish Easy Targets for Fishers, Suggests Study

First Posted: Nov 14, 2012 02:02 AM EST

The latest research by an Australian team working in the Philippines into the effects of marine reserves states that big fish residing in the marine reserves are not capable of protecting themselves from fishers armed with spear guns waiting outside the reserve.

The researchers say there is good fortune awaiting fishers who obey the rules and respect reserve boundaries -- in the form of big, innocent fish wandering out of the reserve.

"There are plenty of reports of fish, both adults and juveniles, moving out of reserves and into the surrounding sea. Having grown up in an area where they were protected from hunting, we wondered how naïve they would be with regard to avoiding danger from humans," says Fraser Januchowski-Hartley of the ARC Centre of Excellence for Coral Reef Studies.

The answer is: pretty naive. "Educated fish normally turn tail and flee when a diver armed with a spear gun approaches within firing range of them. The typical flight distance is usually just over four meters," he explains.

"However in our studies of marine reserves in the Philippines, Vanuatu and Papua New Guinea, where spear fishing remains a major way of harvesting table fish, we discovered that reserve-reared fish were much less wary and allowed people to get much closer."

"The fish are literally more catchable."

For their study the team observed the behavior of fish 200 m within the boundaries of marine reserves and 200 m outside the reserve. With the help of underwater markers and measuring tapes they measured the flight initiation distance of fish targeted locally by spear fishers. With this they indicated how close a fisher could approach before a fish decided to turn tail and flee.

They noticed that fish living outside the reserve were quicker in protecting themselves from divers, they took flight at distances a meter or two further away than ones living within the reserve. The team also established a 'naivete radius', a distance of 150 meters from the boundary, where the fish from the reserve spill out.

Through this study the team suggests that fishers are more likely to catch fish that stray out of the reserve, and so improve the local fish harvest. Thereby helping fishers become more supportive of marine reserves.

"In these parts of the oceans, spear fishing is still very much about survival for humans and putting food on the family table -- so it is important that local fishers feel they are deriving some benefit from having a local area that is closed to fishing, or they may not respect it," says Dr Nick Graham, a co-author on the study.

"This information is also useful in traditional reserves where fishing is taboo most of the time, but then they are opened for fishing by village elders just a few days a year."

"On the face of it, this work suggests that marine reserves can play an important role in putting more fish on the table of local communities in these tropical locations -- as well as conserving overall fish stocks and replenishing those outside the reserve," Januchowski-Hartley says.

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