Featured Elasmobranch

February 2005

PRICKLY SHARK

ECHINORHINUS COOKEI (PIETSCHMANN, 1928)

FAMILY SQUALIDAE (DOGFISH SHARKS)

Identification: A moderately large shark with a flabby body, skin consists of large modified dermal denticles that form small thorn-like projections scattered over its body and fins, hence the common name “prickly shark”. Denticles appear to decrease in size moving dorso-ventrally, with skin surface smooth to the touch directly beneath insertion of the pectoral fins. Labial grooves and lateral line are pronounced and easily discernable. Gill slits increase in length moving posteriorially. The first dorsal fin originates behind the insertion of the pelvic fin. Bladelike teeth, with a single smooth edged-cusp and one the three small cusplets. Coloration upon capture is slate-gray to brown or black, with posterior fin edges being darker.

Size: Maximum reported length is 4m.

Distribution: Currently the distribution is thought to be Pan-Pacific, in both temperate and tropical waters. In the Eastern Pacific E. cookei has been caught from Moolach Beach, Oregon to Chile.

Habitat: Normally characterized as a deepwater species ranging from 100 - 650m. However, numerous capture records are in less 35 m of water bringing into question the depth range predominately used this species. Visual observations from scuba divers and submarines indicate associations with mud or sand substrate, where sharks orient themselves on or very near the bottom.

Biology: The length at sexual maturity for E. cookei females is reported to be 2.9 m and males are thought to mature at about 2.4m. Females exhibit aplacental viviparity and are highly fecund; a 304.8 cm female specimen was pregnant with 114 pups. Size at birth has been reported to be 21 – 61 cm. Age at maturity and longevity is unknown for this species. Stomach content analysis has been published for 25 individuals, results indicate the diet consists of unidentified teleosts, small sharks, egg cases of other sharks and rays, octopus, squid, and meso-pelagic fishes.

General interest: Although E. cookei is generally referred to in the literature as uncommon or rare, this could be due to artifacts such as infrequent capture, un-disseminated local reports, misidentification and low or non-existent commercial value. Large aggregations (> 30 individuals) have been observed during scuba surveys at the head of the Monterey submarine canyon. Since 1990, 36 individual E. cookei have been tagged. Nine individuals have been resighted or recaptured at the head of the canyon, including one individual that was at liberty for 6 years. Currently researchers at Moss Landing Marine Laboratories are utilizing acoustic telemetry and underwater visual surveys to collected data on the habitat use, and biology of E. cookei in the Monterey submarine canyon. A main area of focus will be to identify any sex-based or seasonal differences in habitat use and movements.

By Cyndi Dawson

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