Sawfish 'use Wi-Fi to find prey'
Washington: Sawfish senses electric fields to find prey, contrary to the widely held perception that they only feed from the bottom of the ocean, says a new study.
An international team, led by the University of Western Australia, says the findings dispel the myth that sawfish are purely bottom feeders who use their saw to rake up the sandy bottom. It provides evidence that the fish, which develop in freshwater river systems, also feed closer to the surface.
The discovery could help save the sawfish from extinction by providing vital information for captive breeding programs and strategies to save them from falling victim to commercial fishing nets, the 'Current Biology' journal reported.
"Officially they have never been targeted and so they are caught only as by-catch. Unfortunately, their saws are often taken for trophies by both commercial and recreational fishers and their fins are popular in the shark fin trade.
"The more we know about them the better we can protect them. The first step might be to develop by-catch diversion strategies. And for captive sawfish, we can make sure they get the right stimuli to survive and reproduce," Barbara Wueringer, who led the team, said in a varsity release.
Sawfish share a common ancestry with shovelnose rays and it's believed they evolved their saw-like rostrum with teeth on the outside to extend their niche in the underwater world.
Once common in tropical and subtropical regions, freshwater sawfish spend their young life in river systems until they reach adulthood -- about age 10 and at least three metres long -- when they move into the ocean.
Sawfish feed on catfish, mullet and freshwater prawns. One strike from their saw can split a fish in half.