US officials say 6 sea lions found dead on river likely died from the heat

The deaths of six sea lions found in traps on the Columbia River in the U.S. earlier this month were likely caused by the heat, and not by gunshots as officials first suspected, the National Marine Fisheries Service said.

Oregon and Washington officials had been trapping the animals as part of a federally approved removal process because they feast on salmon at the Bonneville Dam.

Federal and state officials initially said the sea lions had been shot, but they did an about-face after necropsies by state and federal experts found no evidence of bullet wounds.

The fisheries service said Wednesday the results of necropsies on all six animals were …