27 September 2012 Last updated at 07:24 ET

Brazil's northeast coast boasts warm waters and beautiful beaches. But the coastal waters are home to many aggressive sharks, and in the last 20 years a spate of attacks has made this one of the most dangerous places in the world to swim. Rob Sawers reports.

In the last week of August, the body of Tiago Jose de Oliveira da Silva, 18, was found in the sea just south of Recife, in north-eastern Brazil. An autopsy ruled he had been killed by sharks.

His death was the 56th shark attack in Recife in 20 years. What is so shocking about Recife's attacks is that so many of them are fatal - 21 of the 56, a death rate of about 37%. This is much higher than the worldwide shark attack fatality rate, which is currently about 16%, according to Florida State Museum of Natural History .

According to Dr Rosangela Lessa of the Federal Rural University of Pernambuco (UFRPE), and president of the state's team trying to reduce shark attacks, the blame lies with recent environmental disturbances in the region. It is also because there are lots of beachgoers - and lots of aggressive sharks - sharing the water.

Scientists believe most of these attacks are committed by two species - bull sharks and tiger sharks - but forensic evidence has only been able to confirm the species responsible in eight of these attacks.

Bull sharks are considered the be one of the most dangerous shark species, with many proven attacks against man.

There are almost two million people in Recife and surrounding areas, and there are many beaches conveniently located in and around the city. But, some 700 metres off the coast lies a deep trench running parallel to the beaches near the city.

Sharks use this trench as a migratory route and emerge from it to hunt in the shallows.

It is Recife's Port Suape, though, that many see as the biggest cause of the recent attacks. Located 20km (12 miles) south of Boa Viagem Beach, where most of the attacks have occurred, the port has been the cause of much disturbance for marine life along the coast and the nearby estuaries.

Read more from the original source:

The danger lurking off Brazil's beaches