Anti-shark sensors

Underwater sensors that detect large sharks and tweet warnings to beachgoers will be installed in the sea near Sydney this summer. The devices will be triggered only by sharks previously caught by fisheries officers and equipped with an electronic tag attached to their fins. The north coast of New South Wales had half of Australia’s shark attacks last summer. The NSWstate government yesterday unveiled the A$16 million (NZ$16.9m) ‘‘shark mitigation strategy’’.