Viral attack
A previously unknown virus could be contributing to the global decline in number of marine mammals. Studies were conducted by on declining populations of southern elephant seals of Macquarie Island, 2,000 km south of mainland Australia. The study revealed that lice that infect the seals carry a type of virus called arbovirus, which might infect the brains of the seals. The seals whose immune systems are already weakened by pollution are washed ashore along with the tide i.e. beached. Beaching could prove fatal for the weakened seals ( New Scientist , May 12, 2001).