How to Identify Western Brook Lamprey

To identify Western Brook Lamprey (Lampetra richardsoni), look at these key features.

Physical Characteristics

Body shape

eel-like

Coloration

Adults are typically dark grey to olive-brown dorsally, fading to lighter grey or yellowish-white ventrally. Ammocoetes are uniformly light brown or yellowish.

Scale type

none

Mouth position

terminal

Distinctive features

Jawless, circular sucking disc mouth with blunt teeth (adults), Seven external gill openings (pore-like) on each side of the head, Absence of paired fins, Two distinct dorsal fins, often narrowly separated or continuous in some individuals, Lack of scales

Dorsal fin

Two distinct dorsal fins, the first smaller and triangular, the second larger and continuous with the caudal fin. The separation between the two dorsal fins can be minimal.

Tail fin

Slightly spatulate or rounded caudal fin, continuous with the second dorsal and anal fins.

Pectoral fin

Absent

Distinctive fins

No paired fins (pectoral or pelvic).

Identification Tips

1. 1

   Mouth

   Adults have a circular, jawless sucking disc. The teeth are blunt and not sharply pointed, distinguishing them from parasitic lampreys.

2. 2

   Size

   Adults are relatively small, typically ranging from 10 to 18 cm (4 to 7 inches) in total length. Ammocoetes can reach similar lengths before metamorphosis.

3. 3

   Dorsal Fins

   Observe the two dorsal fins. In Lampetra richardsoni, they are typically distinct but may be narrowly separated or almost continuous, especially in larger individuals. The second dorsal fin is continuous with the caudal fin.

4. 4

   Coloration

   Adults are generally dark grey to olive-brown above, lighter below. Ammocoetes are uniformly light brown or yellowish.

5. 5

   Absence of Parasitic Behavior

   Unlike parasitic lampreys, adult Western Brook Lampreys do not attach to other fish. If a lamprey is observed attached to a fish, it is not a Western Brook Lamprey.

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