Sixteen years after an explosion on the Deepwater Horizon oil rig unleashed more than 4 million barrels of oil into the Gulf of Mexico, life in the deep sea has yet to recover.

A new study finds that in the first few years after the 2010 disaster, populations of octopus, squid, krill, shrimp, and lanternfish declined by at least 60 percent. The research, based on acoustic surveys and thousands of netted samples across a broad swath of the Gulf of Mexico, found little evidence that life in the deep sea has bounced back.

The study, published in the Proceedings of the National Academy of Sciences, described the losses as “the fastest and most severe” decline of animal life in the ocean layer that extends from about 600 feet deep to more than two miles down. While researchers stopped short of concluding that the oil spill had caused the declines, they said it was “the most parsimonious explanation.”