Description
Isopsetta isolepis (Butter Sole)
(Other common names: Scalyfin, Bellingham Sole, Skidegate Sole)
Figure 53.13
DescriptionLength: 55 cm.
Mouth: small, terminal; narrow gape; asymmetrical; maxillary extends to point below anterior edge of lower eye; jaws with teeth strongest on blind side; snout round and pointed.
Body: caudal peduncle moderate; caudal fin rounded; pectorals small with blunt points; anal fin with small sharp spine; lateral line canal is slightly arched over the pectoral fin; dorsal accessory branch present.
Color: gray with irregular blotches on eyed side; white on blind spots, bright yellow on tips of dorsal and anal fin.
Depth: up to 366 m; usually shallower.
Habitat: soft silty substrate; in shallow waters in summer and deeper waters in winter.
Season: spawn in late winter-spring (February to late April; as cited in Hart, 1973).
Diet: molluscs, worms, crustaceans, and forage fish (e.g., herring).
Predators: not determined.
Distribution: southern California to Alaska.
Scale DescriptionScale Type: ctenoid on eyed side; ctenoid on head and fin rays; partly cycloid on blind side (Batts, 1964).
Relative Scale Size: large.
Position of Scales on Body: along lateral line; on head and fins; also on blind side; imbricated (Hart, 1973).
Overall Scale Shape: oval with elongated lateral fields that are 2:1 the width of the anterior field (Batts, 1964).
Focus and Circuli: the focus is approximately one-quarter of the total scale length from the outside edge of the posterior field (Batts, 1964). The circuli are compact and generally continuous between all fields, but are more compacted in the posterior field (Batts, 1964).
Radii: numbers are variable and not diagnostic. The radii are in the anterior field and may also be present in the anterior portion of the lateral fields (radii not present in all fields; Batts, 1964). The outer edge of the anterior field is smooth to slightly scalloped, depending on the spread of the radii. Intermarkings absent (Batts, 1964).
