One of the best pieces of survey equipment I’ve used is the seine. I enjoy it so much because even the most dull stream is full of aquatic invertebrates and small fishes. The piece of equipment is composed of two long poles with a net strung between them. On the top side of the net there were floats, and on the bottom were weights.
When I was working on creating a photographic guide to the fishes of the Buffalo River, a dear professor and I went out and seined many streams and ponds in the Buffalo River basin. If you have never tried it, it’s a great way to sample aquatic systems. It pulls up all of the macro invertebrates and the smallest fishes.