Northern Brook Lamprey
  • Side view adult. All adults are breeders, the adult phase is short, fish do not feed, but spawn and die.
  • Side view adult. All adults are breeders, the adult phase is short, fish do not feed, but spawn and die.
  • Side view adult (female distended with eggs). All adults are breeders, the adult phase is short, fish do not feed, but spawn and die.
  • Bottom view adult. All adults are breeders, the adult phase is short, fish do not feed, but spawn and die.
  • Top view adult. All adults are breeders, the adult phase is short, fish do not feed, but spawn and die.
  • Head-on view adult. All adults are breeders, the adult phase is short, fish do not feed, but spawn and die.
  • Close-up flank.
  • Close-up head.
  • Close-up mouth and snout.
  • Close-up tail.
  • Close-up dorsal fin.
  • Close-up teeth: Notice the unicuspid circumoral teeth and close-together supraoral teeth.
  • Close-up mouth: Notice the unicuspid circumoral teeth and the supraoral teeth which are very close-together.
  • Close-up dorsal fin: The two lobes of the dorsal fin are broadly connected.
  • Side view: Count myomeres from branchial pores to anus. Notice the connected dorsal fins.
  • Close-up anterior: There are 46-56 trunk myomeres. Start myomere count behind last branchial pore.
  • Close-up tail of an ammocoete (larval stage).
  • Side view of an ammocoete (larval stage): Notice the hood-like covering of the mouth.
  • Close-up head of an ammocoete (larval stage).
  • Close-up mouth of an ammocoete (larval stage): Juveniles lack teeth.
  • Comparison of a juvenile (top) and two adults. All adults are breeders, the adult phase is short, fish do not feed, but spawn and die.
DescriptionSimilar Species
Family
Lampreys (Petromyzontidae)
Body
Mouth and Snout: Sucking disk in adults, flexible hood in juveniles, no jaw. Teeth small and blunt in adults; none in juveniles. No barbels. This nonparasitic species has a sucking disk that is about the same in diameter as its body. Gill openings consist of seven circular holes. Body Pattern: Solid color. Dark grayish brown or gray on dorsal surface and flanks, grading to light gray/brown, silvery, or off-white ventrally. Lateral pores unpigmented. No scales. Body Shape: Elongate, cylindrical, flexible body. Typically 100-135 mm (4-6.5 inches) with a maximum of 171 mm. Ammocoetes may reach slightly longer lengths than adults, with shortening (up to 10%) occuring in transformation to adulthood.
Fins
Rounded tail. Dorsal fin with no spines. No anal, pectoral, pelvic, or adipose fins. The dorsal fin is continuous (not bilobed).
Distinguishing Characteristics
Eel-like body and sucking disk identify the lamprey family. First and second dorsal fin broadly connected. Lateral pores unpigmented. Adult only: maximum disk diameter lesser than maximum body diameter; supraorbital lamina teeth cusps close together, inner circumoral teeth unicuspid. Maximum length 171 mm. 46-56 trunk myomeres. See also similar species information.
Breeding Adults
Lampreys spend most of their lives as ammocoetes. They transform to the adult form in the fall, cease feeding, breed in the spring, and die. The adult form is the breeding form. No photo because it’s the same.
Juveniles
Ammocoete form. Distinguished from adults based on head and mouth characteristics. Ammocoetes lack eyes, have a hood-like covering of the mouth withour a papillary fringe, and have soft sieve like tissue in the mouth. Ammocoetes are brown to gray-brown without eyes.
Hybrids
None known from Wisconsin.
Compare Similar Species
1st and 2nd Dorsal Fins
Lamprey, American BrookSeparated
Lamprey, ChestnutConnected
Lamprey, Northern BrookConnected
Lamprey, SeaSeparated
Lamprey, SilverConnected
Lamprey, Southern BrookConnected
Trunk Myomeres
Lamprey, American Brook64-75
Lamprey, Chestnut51-56
Lamprey, Northern Brook46-56
Lamprey, Sea63-73
Lamprey, Silver46-53
Lamprey, Southern Brook49-57
Lateral Pores
Lamprey, American BrookUnpigmented
Lamprey, ChestnutPigmented
Lamprey, Northern BrookUnpigmented
Lamprey, SeaUnpigmented
Lamprey, SilverUnpigmented (pigmented in large adults)
Lamprey, Southern BrookPigmented
Maximum Disk Diameter Relative to Maximum Body Diameter in Adults
Lamprey, American BrookLess
Lamprey, ChestnutGreater
Lamprey, Northern BrookLess
Lamprey, SeaGreater
Lamprey, SilverGreater
Lamprey, Southern BrookLess
Supraoral Lamina Teeth
Lamprey, American BrookWidely separated
Lamprey, ChestnutClose together
Lamprey, Northern BrookClose together
Lamprey, SeaClose together
Lamprey, SilverClose together
Lamprey, Southern BrookClose together
Inner Circumoral Teeth
Lamprey, American BrookBicuspid
Lamprey, ChestnutBicuspid
Lamprey, Northern BrookUnicuspid
Lamprey, SeaBicuspid
Lamprey, SilverUnicuspid (rarely 1 bicuspid)
Lamprey, Southern BrookBicuspid
Maximum Total Length (mm) in WI
Lamprey, American Brook202
Lamprey, Chestnut271
Lamprey, Northern Brook171
Lamprey, Sea760
Lamprey, Silver385
Lamprey, Southern Brook~170
Similarity Index
Lamprey, American BrookModerately similar
Lamprey, ChestnutVery similar as ammocoetes, moderately similar as adults
Lamprey, Northern BrookN/A
Lamprey, SeaModerately similar
Lamprey, SilverVery similar as ammocoetes, moderately similar as adults
Lamprey, Southern BrookVery similar
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