Mexican environmental authorities said Thursday that 292 sea turtles found dead on the country's southern Pacific coast since Christmas died as a result of a red tide algae bloom.

The number of monarch butterflies that showed up at their winter resting grounds decreased about 53% this year, Mexican officials said Friday. Some activists called the decline "heartbreaking," but the Mexico head of the World Wildlife Fund said the reduction "is not alarming."

The Mexican government officially abandoned the policy of maintaining a fishing-free zone around the last 10 or so remaining vaquita marina. The measure announced Wednesday replaces the fishing-free "zero tolerance" zone in the upper Gulf of California with a sliding scale of punishments if more than 60 boats are seen in the area on multiple occasions.