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Lampetra aepyptera (Abbott, 1860)
Least Brook Lamprey
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G5
State Rank: S2
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): Yes
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: Data Deficient
Element Occurrences (EOs) in Georgia: 14
Habitat Summary for element in Georgia: Ammocoetes associated with mud, silt, and maacrophytes. Adults associated with sand and gravel
The least brook lamprey is eel-like in body shape, but lacks jaws or paired fins. Lampreys have two major life stages, ammocoete (larva) and adult. Ammocoetes have greatly reduced eyes and lack the round sucker disk and rasping teeth of the adult, instead having a hood around the oral opening. The least brook lamprey is a non-parasitic species and has a dorsal fin divided in two by a deep notch. The number of myomeres (muscle bands) between the last gill pore and the cloaca ranges from 50 to 61, but is usually 54 to 56. Adults are greyish in color with variable olive or yellowish tones, darker above and lighter below; when spawning they may become mottled. Adults range in size from 75 mm to a maximum of 180 mm (3 - 7 in).
There are several other lamprey species within the range of least brook lamprey with which it could be confused. Chestnut lamprey (Ichthyomyzon castaneus), mountain brook lamprey (Ichthyomyzon greeleyi), Ohio lamprey (Ichthyomyzon bdellium), and southern brook lamprey (Ichthyomyzon gagei), overlap in myomere counts, but all have a single undivided dorsal fin. The American brook lamprey (Lethenteron appendix) has a divided dorsal fin, but the myomere counts are greater, ranging from 63 to 73.
Generally in smaller upland streams with sand and gravel substrates and slow to moderate currents, often with aquatic macrophytes. Ammocoetes burrow into deposits of fine sand and detritus with reduced currents along banks or in pools. Adults hide among rocky or woody debris. Streams in which they are found typically have clear water and permanent flow.
Ammocoetes filter feed on algae, bacteria, and detritus. Adults do not feed, and live on energy stores built up during their ammocoete stage.
The ammocoete stage lasts from 4 to 6 years, which they spend filter-feeding while buried in fine sand and detritus. Transformation to the adult stage begins in late summer and extends through the fall. During this period, they cease feeding and the digestive system becomes reduced and nonfunctional. Externally, they lose the oral hood and the mouth becomes a sucking disc. Additionally the eyes enlarge and become functional, and the fins elongate. Least brook lamprey spawn at the upper end of shallow riffles as water begins to warm in early spring. Spawning occurs in groups over small pit-like nests excavated in the stream substrate. Migration is minimal and spawning occurs in the same streams in which they lived as ammocoetes. After spawning, all adult least brook lamprey die.
Ammocoetes are readily collected by electrofishing throughout the year; adults may be collected using the same method during the limited time period they exist
Least brook lampreys are widespread in the Ohio River drainage and the Mobile Bay drainage with additional populations in Mississippi and the Ozarks. There are also isolated populations on the Atlantic slope around Chesapeake Bay and in North Carolina. In Georgia they have been collected from the Coosa basin and from the Lookout Creek watershed of the Tennessee drainage.
Least brook lamprey may be threatened by increased sedimentation, which reduces spawning habitat and alters substrate characteristics for ammocoete burrowing. Increased turbidity and siltation may also interfere with ammocoete filter feeding and respiration. Ammocoete survival is linked to cooler water and stable flow, which may be altered by reductions in canopy cover and groundwater inputs. Additionally, dams and poorly constructed culverts may reduce population connectivity and eliminate access to spawning or larval habitats.
It is known from several widespread locations in the Coosa basin, but few collections within the last 20 years. In the Tennessee drainage it was recently collected from two streams of the Lookout Creek watershed.
Conservation of this species depends on maintaining water quality and flows from springs and headwater streams within its range. Revegetating stream corridors, limiting groundwater withdrawal, and removal of dams on springs and groundwater-fed headwaters would be beneficial to this species. Additionally, the reduction of excessive sedimentation from land disturbing activities would improve available habitat.
Boschung, H.T. & R.L. Mayden. 2004. The Fishes of Alabama. Smithsonian Institiute, Washington DC. 736 pp.
Dawson, H.A., B.R. Quintella, P.R. Almeida, A.J. Treble, & J.C. Jolly. 2015. The ecology of larval and metamorphosing lampreys. In Lampreys: biology, conservation and control (pp. 75-137). Springer, Dordrecht.
Etnier, D.A. & W.C. Starnes. 1993. The Fishes of Tennessee. Univ. Tennessee Press, Knoxville, TN. 681 pp.
Jenkins, R.E. & N.M. Burkhead. 1993. Freshwater fishes of Virginia. Am. Fish. Soc., Bethesda, MD. 1079 pp.
Pflieger, W.L. 1975. The Fishes of Missouri. Missouri Dept. of Conservation, Jefferson City, MO. 343 pp.
Renaud, C.B. 2011. Lampreys of the world. An annotated and illustrated catalogue of lamprey species known to date. FAO Species Catalogue for Fishery Purposes. No. 5. Rome, FAO. 109 pp.
Smith D.M., S.A. Welsh, & P.J. Turk. 2011. Selection and preference of benthic habitat by small and large ammocoetes of the least brook lamprey ( Lampetra aepyptera). Environ Biol Fish 91:421–428.
Marcus Zokan
2/4/2019
