Documented incidence of the northern brook lamprey is limited to one medium sized stream in the northeast in Delaware County. It was recently discovered in 1998 when ten juveniles and four adults were collected using pulsed DC tote-barge elctrofishings equipment. Previous known distribution of this species included Wisconsin, Minnesota and Missouri. It is not likely that this discovery represents a recent expansion of their range into Iowa due to several impassable dams which would prevent upstream migration. This species has probably gone unidentified because of the lack of proper sampling equipment.

Adult northern brook lamprey are more easily differentiate from American brook lamprey but adults are less commonly collected. The northern brook lamprey ammocoetes may have been collected in past sampling but misidentified as american brook lamprey ammocoetes.

The dorsal fin of the Northern brook lamprey is continuous, not divided into two distinct fins. The mouth is a sucking disc, teeth are small and poorly developed. Ammocoete length range from 130 to 170mm while adults range from 115 to 170mm in length.

The secretive nature of its habits makes knowledge of its distribution rather vague and undetermined. The northern brook lamprey is non-parasitic, living 3-5 years as a filter feeding larvae (ammocoete) in the bottom sediments of streams before transforming into a non-feeding adult in mid-summer to late fall. The following spring the adult lamprey spawns completing its life cycle.

Like the other lampreys in Iowa, these fish have no angling value to anglers.