Big Fishes That Grow Up In Marines Reserves Can’t Defend Themselves Outside The Reserve

Looking for easy pickings, spear fishers often wait for big fish to wander out from their marine reserve since the fish don't know how to defend themselves..

"There are plenty of reports of fish, both adults and juveniles, moving out of reserves and into the surrounding sea," said Fraser Januchowski-Hartley of the ARC Centre of Excellence for Coral Reef Studies. "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.

"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 metres," he added.

A study, which was conducted to learn the "flight initiation distance" of fish targeted locally by spear fishers, used underwater markers and measuring tape to track the distance. The "flight initiation distance" is how close a fisher can get to a big fish before it escapes.

The study found that fish living in the fished area were more careful as they turned and escaped at a distance of a meter or two of the fishers' approach. However, it was not the same with the reserve fishes.

"However in our studies of marine reserves in the Philippines, Vanuatu and Papua New Guinea, where spearfishing 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," Januchowski-Hartley said.

Dr. Nick Graham, a co-author on the study, also found that spear fishing is a matter of survival for people there.

"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," he said.

Januchowski-Hartley concluded that these marine reserves help 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."