Featured Elasmobranch

July 2004

WHITE-SPOTTED RATFISH

HYDROLAGUS COLLIEI (Lay and Bennett, 1839)

FAMILY CHIMAERIDAE (SHORTNOSE RATFISHES)

Identification: Large 'rabbit-like' head, a tapering scaleless body, a prominent spine on the dorsal fin base, large, triangular pectoral fins, with a fleshy base, and luminescent green eyes in life. Dorsal body surface silvery gray to brown with varying hues of blue, gray, and green, and covered with numerous white spots. Adult males have a club-like appendage, referred to as a tenaculum, on their forehead.

Size: Maximum reported total length is 100 cm.

Distribution:Southeast Alaska to Cedros Island, Baja California and the northern Gulf of California.

Habitat: Intertidal to 971 m deep, becoming increasingly deeper in the southern part of their range. They prefer water temperatures between 45-48 °F. White-spotted ratfish prefer cobblestone or mud bottoms, orienting themselves near areas of vertical relief.

Biology: White-spotted ratfish are oviparous, laying brown spearlike egg cases measuring 13 cm that require 18 to 30 hours to expel during parturition. Egg cases are deposited in soft or gravel sediment. Development takes approximately 12 months with newborns emerging at 45 cm. Maturity for females occurs between 41-47 cm total length and for males between 35-44 cm total length. White-spotted ratfish feed on mollusks, crustaceans, echinoderms, polychaete worms, and fishes. They are feeble swimmers, typically foraging on prey items with limited escape responses.

General interest: This species is taken as a bycatch in longline and trawl fisheries. The flesh is edible, but no directed fishery exists for them in the eastern North Pacific. Although not considered dangerous, the dorsal fin spine is venomous and can inflict a painful wound if this fish is mishandled.

By Robert Leaf and David A. Ebert

Pacific Shark Research Center, Moss Landing Marine Laboratories
8272 Moss Landing Road, Moss Landing, CA 95039
rleaf@mlml.calstate.edu