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Although ammocoetes are blind, adult Northern brook lamprey have small eyes. This species also has a lateral line through which the fish may sense vibrations.
Communication Channels: tactile ; chemical
Perception Channels: visual ; tactile ; vibrations ; chemical
The Minnesota DNR lists northern brook lamprey as a species of special concern. In order to keep game fish populations high and parasitic sea lamprey populations low, a lampricide treatment is put into streams and rivers where many lamprey, including non-parasitic northern brook lamprey, reside. This lampricide, among other poisons and pollutants, is adversely affecting population size. There is not currently a direct management/conservation plan in place for this species.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Northern brook lamprey have two developmental stages: ammocoete (larval) and adult. Larvae hatch approximately 2 weeks after egg fertilization and drift downstream before burrowing into the substrate. Once settled in burrows, larvae feed on suspended algae, bacteria and other detrius for 5-6 years until they metamorphose into non-feeding juveniles, typically in the fall. The transformation process lasts for 2-3 months. Juveniles spend 4-6 months drifting until spring, when spawning occurs and they become sexually mature adults. Adults die shortly after spawning.
Development - Life Cycle: metamorphosis
There are no known adverse effects of northern brook lamprey on humans.
Although there is little known positive impact of northern brook lamprey on humans, fishermen do occasionally use this species as bait
Although morthern brook lamprey often share habitat with mayfly nymphs and small mussels, there is little evidence that there is any competition amongst these species. Unlike many lamprey species, this species is non-parasitic. There is currently no research available regarding parasites of northern brook lamprey.
Northern brook lamprey only feed as ammocoetes. During this time, they feed mainly on organic detrius, diatoms, desmids, protozoans, algae and pollen.
Plant Foods: pollen; algae
Other Foods: detritus ; microbes
Foraging Behavior: filter-feeding
Primary Diet: herbivore (Algivore); detritivore
Northern brook lamprey are found in many areas of the midwestern and northeastern United States, including the Mississippi River drainage in Wisconsin, northeastern Illinois, and northern Indiana, and in parts of Canada. They are also found in a Lake Erie tributary in New York and certain tributaries of the St. Lawrence River in Quebec, Canada.
Biogeographic Regions: nearctic (Native )
The habitat of northern brook lamprey varies throughout the life cycle. Adults are generally found in areas of rapidly flowing water above a very coarse bed, spawning and then laying eggs in crevices beneath rocks and boulders. Ammocoetes (larvae) are generally found in the the calmer waters of brook, stream and river side channels where there is fine sediment or organic debris in which to burrow.
Range depth: 0.7 (low) m.
Habitat Regions: temperate ; freshwater
Aquatic Biomes: rivers and streams
Northern brook lamprey typically live for 5-8 years in the wild, dying within a few days of reaching sexual maturity and completing mating. There is no data available regarding captive lifespan.
Average lifespan
Status: wild: 7 years.
Typical lifespan
Status: wild: 5 to 8 years.
Northern brook lamprey appear very similar throughout their life cycle. This species has a continuous dorsal fin that may or may not be divided by a small notch and is connected to a round, short caudal fin. Individuals are grayish brown dorsally with a pale median line down the back and a lighter ventral side, with the posterior end darker in color (almost black). There are a few differences between ammocoetes and adults: ammocoetes have neither eyes nor a sucking disk mouth (they have a hooded mouth instead). Adults have eyes and disk-shaped mouths with small, poorly developed teeth. Once adults are of breeding age it is possible to differentiate between the sexes (males have a urogenital papilla and females have an enlarged post-anal fold).
Average mass: 2.2 g.
Average length: 16 cm.
Other Physical Features: ectothermic ; bilateral symmetry
Sexual Dimorphism: female larger
This species is prey for many larger fish throughout its life. While eggs and ammocoetes are particularly vulnerable, adults may be consumed as well. Known predators include rainbow trout, rock bass and brown trout.
Known Predators:
During mating, 3-7 northern brook lamprey will build a nest together and spawn in groups of 10-30. Once eggs are fertilized and laid they are often covered with the substrate surrounding the nest.
Mating System: polygynandrous (promiscuous)
Northern brook lamprey spawn in the spring at approximately 6 years of age, just after reaching sexual maturity. Females lay thousands of eggs, possibly due to high mortality rates during the early stages of the species' life cycle. Eggs hatch 2-4 weeks after fertilization.
Spawning is initiated when water temperatures are between 13 and 20.5°C. Males begin nest building by moving stones and gravel to create a small dip in the substrate within shallow, pool-riffle, high-gradient stretches of streams.
During spawning, these lampreys coil together in groups of 3 to 7 individuals before going into the nest. Once in the nest a male attaches to, but does not wrap around, a female (as in some other lamprey species) to complete egg fertilization. Adults then leave the nest and die soon thereafter.
Breeding interval: Northern brook lamprey spawn once during their lifetimes.
Breeding season: Spring
Range number of offspring: 1,115 to 1,979.
Average number of offspring: 1,200.
Range age at sexual or reproductive maturity (female): 5 to 7 years.
Range age at sexual or reproductive maturity (male): 5 to 7 years.
Key Reproductive Features: semelparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
There is no parental investment by adults of this species as they die soon after egg fertilization.
Parental Investment: no parental involvement
