90% of all botulism outbreaks are caused by improperly prepared food.
There is one rare type of botulism, that strain being related to Clostridium botulinum found in soil world wide. That rare type botulism has not yet been associated with any human or animal outbreak.
An outbreak of botulism related to the tragic conditions in the aftermath of the tsunami is highly unlikely.
IIRC, where I live we've had a occasional botulism worry with dead geese. Rotting meat, especially in water, is anaerobic.