Northern brook lamprey

Characteristics

The dorsal fin 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 long.

Distribution

Documented occurrence of the Northern Brook Lamprey is limited to one medium-sized stream in northeast Iowa in Delaware County. The secretive nature of its habits makes knowledge of its distribution unclear and undetermined. It was discovered in 1998 when ten juveniles and four adults were collected using pulsed DC tote-barge electrofishing 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.

Foods

Larval stage eats small plants, animals and bits of organic matter; adult digestive system is non-functional showing that no food is consumed from fall until spring.

State Record

State Records are not documented for non-game species.

Expert Tip

none

Details

Adult Northern Brook Lamprey are more easily differentiated from American Brook Lamprey, but adults are less commonly collected. The Northern Brook Lamprey ammocoete may have been collected in past sampling, but misidentified as American Brook Lamprey ammocoete.

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.

Recent stream sampling information is available from Iowa DNR's biological monitoring and assessment program.