Researchers: Fish Become Wary Of Spearfishermen; 'The Fish Tended To Move Off'

Papua

TOWNSVILLE, Queensland -- Fish are not as dumb as people sometimes think: marine scientists have found that fish that are regularly hunted with spearguns are much more wary and keep their distance from fishers.

In investigating the effects of marine areas closed to fishing by customary laws, an international team of researchers working in the Pacific found that fish exposed to speargun fishing take flight much earlier when a diver approaches compared with those living in protected zones.

"We were studying the effect of the customary reef closures which many groups in the Pacific use," explains team member Fraser Januchowski-Hartley of the ARC Centre of Excellence for Coral Reef Studies at James Cook University and the Wildlife Conservation Society.

"In developed countries marine areas closed to fishing are a fairly recent idea – but in the Pacific islands, people have been using them for generations, for traditional reasons."

One of the issues the team was interested in was whether the existence of a closed area changed the behavior of the fish inside it, compared to the behavior of fish outside the area.

Their study took place at Muluk in Papua New Guinea where the local chiefs close areas of reef to fishing, sometimes for several years at a time, whenever it seems the fish are becoming a bit shy. The study looked at fish traditionally hunted by the local people including snappers, triggerfish, parrotfish and surgeonfish.

To study the fishes' flight distance, a scuba diver slowly approached the fish and dropped a marker at the point where the diver was when the fish was seen to take flight – and a second marker at the point on the reef where the fish was when it fled. This enabled them to measure the distances at which fish fled from the diver, both inside and outside the protected area.

"Fish which are regularly targeted appeared to have a pretty fair idea of the 3m range of the typical rifle-style speargun used by the local PNG fishers", explains lead author Dr David Feary of University of Technology Sydney (UTS).

"Inside protected areas, the fish tended to move off when the diver closed to within 2-3 meters of them. However those outside the protected zone, where hunting was common, mostly fled when the diver came within 4-5 meters of them."

"Quite simply, the fish in areas that were fished regularly were warier and stayed further away- just far enough that it would be difficult to hit them with the spear gun technology used locally"