Bhubaneswar: Officials of the Chilika wildlife division are making an all-out effort to guard the 15.53sqkm Nalabana avian sanctuary located in the core area of lake against illegal intrusion by local fishermen, who become hyperactive during the winter months.

"There is a ban on fishing in the sanctuary area round the year. But during rains when it is submerged in water, fishermen try to sneak in on the excuse that its boundary markers are not visible," said Chilika divisional forest officer Bikash Ranjan Dash.

Keen to enforce the ban strictly in Nalabana, forest officials have so far seized two boats for making illegal entry into the sanctuary. Dash said that last year, around 12 boats had been impounded and more than a dozen fishermen arrested for violating the ban.

"We have deployed 20 persons, including forest guards, to keep tabs on fishermen trying to violate the ban. Our officials are also carrying out boat patrolling in the area which has three watchtowers," he said.

Sources said Nalabana was favoured by the birds because they got enough food stock on the mudflats of the island. "Though birds can be seen in almost all areas of Chilika during the winter their largest congregation is in Nalabana," said environmentalist Shashi Kant Mishra.