A conservation group said that the operations of a dam along the Union River in downtown Ellsworth caused the death of thousands of fish earlier this month. The Downeast Salmon Federation released videos on Wednesday showing what it said are thousands of dead adult river herring, or alewives, along the water and banks immediately downstream of the Ellsworth dam, which is operated by Brookfield Renewable. Brett Ciccotelli, the restoration and engagement coordinator with the federation, blamed this kill on fish likely finding their way through broken wooden flashboards on top of the dam, which have since been repaired. “This year, they found this gap on the flashboards, went over the gap, or through the gap, and smashed on to these ledges below,” Ciccotelli said.