Despite frequent natural calamities, worsening environment and growing salinity in the Sundarbans, the number of Bengal tigers has risen, observes the state minister for forest and environment.

Hasan Mahmud, the minister, made the observation last week, citing the ongoing track monitoring survey by the forest department and Wildlife Trust of Bangladesh.

He was speaking at the launch of the country's first Tiger Action Plan on January 25.

The latest survey finds the number of big cats ranging between 400 and450.

Censuses in 35 years till 2009 put it between 350 and 450, while in last nine years at least 29 tigers were killed by villagers.

Noted tiger experts do not agree with the state minister as they say disturbances in the mangrove forest have only increased in recent years.

"I don't see any reason the number of tigers should rise. Maybe that remains stable,” said tiger expert Dr Manirul H Khan of Jahangirnagar University.

Most of the surveys conducted so far were unscientific and the numbers they gave of tigers were mere estimates, he continued.

"Not all parts of the forest are evenly claimed by the cats as their territory. So monitoring

tracks or counting pugmarks cannot give the exact number.”

Instead, adds Manirul, the camera census could bring out the exact number.

"I think the number is less than 400 and has not increased recently," said Dr Manirul.

The last pugmark survey by the forest department and United Nations Development Programme (UNDP) in 2004 estimated the number to be around 440 including 21 cubs.

Dr Manirul thinks the UNDP survey overestimated the tiger populace.

Earlier in 1975, Bubert Hendrichs conducted a field survey in compartments 3-6,29-31, and 46-50. He estimated the tiger count at350.

In 1982, Margaret Salter conducted a sample and field survey and estimated the number of tigers was 425.

Rex Gittins conducted a survey in 1984 over a 110-square kilometre area of the Sundarbans South Wildlife Sanctuary and found the number to be 430 to 450.

In 1992, the forest department collected data from people working in the Sundarbans area and estimated the count to be359.

The following year. Dhan Bahadur Tamang conducted pugmark census over 350 square kilometres of different compartments in the Sundarbans and put the number at 362.

In last nine years since 2000,193 people were killed by tigers while 23 tigers were beaten to death and others were found dead in the forest, say the official records of the forest department.

Khasru Chowdhury, a tiger expert who has been visiting the Sundarbans for over last 30 years, said disturbance in the world’s largest mangrove forest has been increasing day by day.

He pointed out that tigers are very sensitive animals and a small disturbance could hamper their regeneration process.

"In recent years, we did not see any significant improvement in forest environment that could help tiger population rise.”

Besides, he added, the stock of tigers' prey has been depleting causing food shortage for the big cats. That tigers are often entering the villages shows they are suffering from a food crisis in the forest.