How to Identify Mottled Sculpin

To identify Mottled Sculpin (Cottus bairdii), look at these key features.

Physical Characteristics

Body shape

flat

Coloration

Highly variable, typically mottled brown, gray, or olive with darker blotches and saddles on the back and sides, providing excellent camouflage. The belly is usually lighter, often whitish or yellowish. Fins are often banded or spotted.

Scale type

none

Mouth position

terminal

Distinctive features

Large, broad, flattened head, Large pectoral fins that resemble wings, Two dorsal fins (first spiny, second soft-rayed), Absence of scales, skin is smooth or covered with small prickles (spinules), Preopercular spine (a sharp spine on the cheek bone, typically blunt or absent in C. bairdii compared to some other sculpins), Eyes located dorsally on the head

Dorsal fin

Two dorsal fins; the first is short with 6-9 spines, the second is longer with 15-18 soft rays. The two fins are typically separated or barely joined.

Tail fin

Rounded or slightly emarginate caudal fin.

Pectoral fin

Large, fan-like pectoral fins with 13-16 rays, extending well beyond the origin of the anal fin.

Distinctive fins

Pelvic fins are thoracic, located beneath the pectoral fins, with one spine and 3-4 soft rays.

Identification Tips

1. 1

   Head Shape

   Look for a distinctly large, broad, and flattened head that tapers to a more slender body.

2. 2

   Coloration and Pattern

   Observe the mottled brown, gray, or olive coloration with irregular dark blotches and saddles, which provides excellent camouflage against rocky substrates.

3. 3

   Scales

   Confirm the absence of true scales; the skin may appear smooth or have small, scattered prickles (spinules), particularly along the lateral line or on the back.

4. 4

   Dorsal Fins

   Note the presence of two dorsal fins, with the first (spiny) typically separated or barely connected to the second (soft-rayed).

5. 5

   Pectoral Fins

   Identify the large, fan-like pectoral fins that are often held out to the sides.

6. 6

   Preopercular Spine

   Examine the preopercular spine; in C. bairdii, it is typically blunt or absent, distinguishing it from some other sculpin species with sharp, prominent spines.

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