Shark nets have been deployed on five beaches on Australia’s far North Coast. The department of Primary Industries (DPI) confirmed that the nets were now in place.
According to the DPI the nets are placed off shore 1640 feet (500m) from the shore in water that is around 32-39 feet (10-12m) deep. The shark nets do not create a fully enclosed area or barrier, and have a gap at the top around 13 feet (4m) from the top of the net to the surface.
The current plan is to have the nets checked twice per day, with a minimum of once per every 72 hours by DPI Contractors. The nets are also fitted with SMART automatic alert devices. The devices are designed to notify contractors when the nets have snared a marine animal. The goal is for the contractor to quickly respond and remove any unintentional catch, such as sea turtles, dolphins or whales.
In addition, each shark net will feature two whale alarms and three dolphin pingers. Both alarms are designed to warn the species of the fishing gear and deter them from becoming entangled.
Dolphin pingers are thought to entice the species into using echolocation which hopefully would help it recognize the shark net and find an alternate path. Whale alarms also send out an audible alert; however, some frequencies appear to have no detectable response in migrating humpback whales.
The Shark Meshing (Bather Protection) Program 2014-15 Annual Performance Report indicated 189 animals were entangled in shark nets from September 1, 2014 to April 2015. According to the report:
Twenty three (23) of those 189 interactions were with threatened or protected species, including:
• 10 White Sharks (all dead);
•4 Green Turtles (3 dead, 1 released alive);
•4 Grey Nurse Sharks (all dead);
•3 Common Dolphins (all dead);
•1 Hawksbill Turtle (dead);
•1 unidentified turtle (released alive).
In addition, there were 131 interactions with other nontarget species, including:
•86 Rays (19 dead, 67 released alive)
•42 Smooth Hammerheads (41 dead, 1 released alive);
•1 Australian Angel Shark (dead);
•1 Thresher Shark (dead);
•1 Silky Shark (dead).
The shark nets will be trialed for six months at which point their continued use will be reevaluated.