We've been fishing a Western Washington reservoir the past few weeks and I'm wondering if anyone has any insight into the sonar picture. The fish are generally 20-25 feet deep and the surface temperature is 45 degrees. There is a red band on the screen where the fish are located. When we clean fish, either the stomachs are empty or we find daphnia (sometimes sticks and small rock). Could the red layer be a band of daphnia?