Hundreds of sea lions have died amid a toxic algae bloom, with some animals becoming dangerous and acting erratically.

Driven mad by toxic chemicals released by algae flourishing in warming oceans, sea lions and other marine mammals are becoming aggressive.

The California sea lion was picked up off a street near beach in Carlsbad. Officials say it may be a case of domoic acid poisoning caused by an algae bloom.

A longtime surfer and marine wildlife advocate was "left shaken" to his core after a relentless and horrifying encounter with a deranged sea creature in California.