Several dead Caspian seals were discovered on the beaches of Aktau, Kazakhstan, on July 3, prompting environmental authorities to launch a new investigation.

Specialists from the Mangystau Region Department of Ecology collected seawater samples from the affected area and have begun laboratory testing to determine the possible cause of the deaths, The Caspian Post reports via Orda.kz.

"We have taken seawater samples from the site. Additional information will be provided after the test results are available," the department said.

The Caspian seal is the only marine mammal native to the Caspian Sea. Listed in Kazakhstan's Red List as an endangered species, it has faced repeated mass die-offs along the coastline in recent years.