Gray Smoothhound, Mustelus californicus
Gray Smoothhound, Mustelus californicus, Juvenile. Fish caught in coastal waters off Point Palmilla, Baja California Sur, January 2018. Length: 47 cm (19 inches).
Gray Smoothhound, Mustelus californicus. Fish caught in coastal waters off Point Palmilla, Baja California Sur, June 2017. Length: 1.42 meters (56 inches).
Gray Smoothhound, Mustelus californicus. Fish caught out from coastal waters off San Diego, California, August 2018. Length: 1.05 m (3 feet 5 inches). Catch and photograph courtesy of Ben Cantrell, San Diego, California.
The Gray Smoothhound, Mustelus californicus, is a member of the Hound Shark or Triakidae Family, and is known in Mexico as cazón mamón. Globally, there are twenty-two species in the genus Mustelus, of which eight are found in Mexican waters, three in the Atlantic and five in the Pacific Ocean.
The Gray Smoothhound has an elongated slender body. They are gray or brown on their back and sides transitioning to white ventrally. Their fins have no distinguishing marks. Albino fish are occasionally encountered. Their head is short and narrow with a pointed snout and large horizontal oval eyes. Their mouth is short and angular with the upper lip fold distinctly longer than the lower lip fold. Their teeth are low and blunt. They have prominent short spiracles behind each eye. Their anal fin is smaller than and originates under the middle of the second of the two dorsal fins; their caudal fin is strongly asymmetrical; the lower lobe is not expanded, indistinct, and with a straight rear edge; and, their first dorsal fin is slightly larger than the second dorsal fin and is broadly triangular with its midpoint being closer to the pelvic fin origin than the pectoral fin base. They have 5 gill slits with the last 2 being over the pectoral fins. They have skin denticles that are elongated and pointed on their flank.
The Gray Smoothhound is a coastal schooling pelagic species found demersal over the continental shelf and within enclosed bays and shallow muddy bottoms at depths up to 245 m (810 feet). Females are larger than males and reach a maximum length of 1.63 m (5 feet 4 inches) whereas males reach a maximum of 1.25 m (4 feet 1 inches) in length. As of January 1, 2023, the International Game Fish Association world record stood at 2.95 kg (6 lbs 8 oz) with the fish caught in coastal waters off San Diego, California in August 2021. They are an abundant species traveling in schools (at times with schools of Leopard Sharks, Triakis semifasciata) or as solitary individuals. They feed on crabs, fish, isopods, shrimp, squid, and polychaetes worms. In turn they are preyed upon by larger predatory bony fish including sharks, specifically the Blacktip Shark, Carcharhinus limbatus, the Dusky Shark, Carcharhinus obscurus, and the Great Hammerhead Shark, Sphyrna mokarran. Reproduction is viviparous with embryos being nourished by yolk-sac placenta. Litter sizes range from two to five pups born live and measuring 20 cm (8 inches) to 30 cm (12 inches). They have an average lifespan of six to nine years. The Gray Smoothhound is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.
In Mexican waters the Gray Smoothhound is a resident of the Pacific but has a limited range being found only along the entire west coast of Baja and throughout the Sea of Cortez; they are absent along the coast of the mainland from Mazatlán, Sinaloa, south to Guatemala.
The Gray Smoothhound is most likely confused with the Brown Smoothhound, Mustelus henlei (first dorsal fin with a fibrous edge), the Sharptooth Smoothhound, Mustelus dorsalis (sharp pointed teeth), the Sicklefin Smoothhound, Mustelus lunulatus (lower tail lobe expanded with a strongly concave rear edge), and the Whitemargin Smoothhound, Mustelus albipinnis (fins with white edges, elongated snout).
From a conservation perspective the Gray Smoothhound has not been formally evaluated. They most likely have had population declines due to extensive commercial fishing pressures and low birth rates. They are considered to be a marginal food fish. They are marketed fresh, frozen, and smoked on a limited basis for human consumption. The preservation of Sharks in general is now a major focus of the Mexican Government with a moratorium having been put in place banning the retention of all sharks taken in Mexican waters. The Gray Smoothhound is considered harmless to humans.