In June I video taped 6 of these building a nest in a small creek. Western brook lamprey dont migrate to the ocean and are not parasitic to fish. They feed on organic goo in the muck.The adults I have seen are about 8 inches The larvae can be found at the mouths of small streams that run into lakes.The adults spawn in gravel and sand at the top of riffles in june.

Its a good thing to know if you fish for bass as bass feed on them. Maybe one of the reasons senkos work so well,especially the darker colors.