(Reuters) - Environmental protection of Sydney's beaches and harbour has created a cleaner marine environment, but is attracting sharks closer to shore chasing fish, say marine experts, after two shark attacks in two days.

Following are points on avoiding or surviving a shark attack:

* Don't swim in a known shark feeding area, such as the estuary of a river, creek or a nearby beach or harbour.

* Don't swim at dawn or dusk, when sharks normally feed. Don't swim amongst schools of fish, particularly swarming bait fish which are a favourite of sharks, or a colony of seals.

* If you do find yourself in the water with a shark, its best to get out as quickly, but as quietly as you can. Don't panic. Panicking and thrashing the water will just make the shark think you are a school of fish.

* If exiting the water is not an option, then crowd together or at least try and make yourself look big. You may intimidate the shark and it might back off. Remember this is the food chain, so size and aggression often win.

* Don't give up, FIGHT!!! Three of the Australians bitten since January survived because they or their rescuer punched the shark in the head. Sharks are sensitive around the eyes, gills and nose and divers who routinely swim with sharks use small batons to prod off sharks if they get too close.

* Even if you find yourself inside the shark, keep on fighting! An Australian abalone diver was swallowed head first up to his chest by a Great White in 2007, but kept punching and poking the shark in the eye until it let him go.

He survived because he was wearing a lead vest which prevented the shark's bite penetrating his chest and because his punching forced the shark to release its bite.

(Editing by Jeremy Laurence)