How are fish counted?

There are a variety of ways to count fish, which is a difficult task.  One popular method is the baited camera, which is a camera with food attached to it.  The fish are attracted to the food and the camera films the fish for a period of time allowing researchers to count them at their leisure.  Counting fish can also be done by sending divers down to examine them.  However, both of these methods can give skewed results and they must be considered carefully.