WELLINGTON, New Zealand (AP) _ Two months of tests failed to find the cause of the deaths of hundreds of rare sea lions on islands south of New Zealand, the government said today.

As many as 1,000 adult Hookers sea lions and 1,400 pups were found dead or dying in the Auckland Islands group, 200 miles south of New Zealand, in January and early February. The die-off depleted what had been a population of only 11,000 to 14,000.

Department of Conservation spokesman Alan Baker said four laboratories examined tissue and blood from the dead sea lions, but found nothing conclusive.

The U.S. Department of Agriculture is carrying out final tests for any viruses. Baker said another possibility is a bloom of toxic algae, known as a ``red tide.''