Sensory Labs was the vision software sub-contractor for a fish counting effort related to fish migration being blocked by a dam. The system uses two techniques for counting fish; a line-scan camera, and a laser sensor for use underwater. The fish are encouraged to swim into the elevator space. As they pass through a vertical light beam detection area, they are counted. Fish leaving the elevator are also detected and the count reduced. When the elevator space has sufficient fish, the chamber is closed and raised. The fish are poured onto the flume where they are de-watered. Fish pass the view of a second line-scan camera and are counted again as they enter the holding tank. Later, staff sorts the fish into a number of trucks. Some fish are taken back down the river, some are moved above the dam, and others are moved further up the river past additional barriers.