How to stop a shark

SHARK ATTACK PREVENTION METHODS OUTLINED IN A REPORT FOR THE SYDNEY SUMMIT:

* Shark spotting and tagging favoured as most effective.

* Most technologies needed more testing before they could be ruled as effective.

* Among the suggestions were both personal and large scale deterrents. They ranged from the complex, such as a wave powered electric fence, to the unusual, with repellant made from necromones - the chemical created during the decomposition of shark meat.

* Physical barriers such as nets or barriers were highlighted as effective but the environmental impact was the main drawback.

* Large scale measures included:

- Barriers both physical and electrical using low voltages to create an invisible electric wall.

- Bubble curtains to create a wall of bubbles aimed at deterring sharks from entering an area.

- Alert systems including warning flags and social media alerts of shark sightings.

* Personal measures included:

- Electromagnetic fields generated by devices on surfboards.

- Wetsuits aimed at confusing or scaring sharks, one such design was similar to a poisonous sea snake but the report warned some sharks actually ate the snakes rather than feared them.

- Some repellants were deemed effective but one chemical was criticised as possibly attracting larger sharks.

(Source: NSW Department of Primary Industries report - Shark Deterrents and Detectors, Review of Bather Protection Technologies)