Nick Smith :

Great answer . Often people forget the seine method or that the best results come from combining the results of several methods. I would add one method -- observation. Not only what you see {use polarized glasses} but also the results from underwater cameras and sonar {fishfinder}. Careful observation with written notes adds a lot to any survey attempt. The notes are important. If after using several methods the results are at odds the notes let you describe the situation in detail to others who may see something you don't. They also provide a collective memory over time { a baseline of data}. ewest