Gray Smoothhound, Mustelus californicus
The Gray Smoothhound, Mustelus californicus, whose Spanish common name is cazón mamón, is a species in the Hound Shark or Triakidae Family, known collectively as cazónes in Mexico. Globally, there are twenty-two species in the genus Mustelus, eight of which are found in Mexican waters, three in the Atlantic and five in the Pacific.
The Gray Smoothhounds have elongated slender bodies. 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. The 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. 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 five gill slits with the last two being over the pectoral fins. They have skin denticles that are elongated and pointed on their flank.
The Gray Smoothhounds are a coastal schooling pelagic species found demersal over the continental shelf and within enclosed bays and shallow muddy bottoms at depths up to 245 meters (810 feet). Females are larger than males and reach a maximum length of 1.63 meters (5 feet 4 inches) whereas males reach a maximum length of 1.25 meters (4 feet 1 inch). 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, isopods, polychaetes worms, shrimp, squid, and a wide variety of small fish. 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 inch) to 30 cm (12 inch). They have an average lifespan of 6 to 9 years. They are a poorly studied species and very little is known about their behavioral patterns.
The Gray Smoothhounds are found in northern Mexican waters of the Pacific including the entire west coast of Baja and throughout the Sea of Cortez; they are absent along the coast of the mainland from Mazatlán 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).
The Gray Smoothhounds are considered marginal food fish and normally a “catch and release”. They are marketed fresh, frozen, and smoked on a limited basis for human consumption. However, things have changed dramatically in Mexico over the last year. A shark in the possession of a local fishermen can be a real problem since a moratorium has been put in place banning the retention of all sharks taken in Mexican waters. They are caught fairly frequently by recreational anglers off Southern California and considered good “game fish.” This species is considered harmless to humans. The Gray Smoothhound Sharks have not been evaluated from a conservation perspective. They most likely have had population declines due to extensive commercial fishing pressures, low birth rates, and low resiliency.
Gray Smoothhound, Mustelus californicus. Fish caught in coastal waters off Point Palmilla, Baja California Sur, June 2017. Length: 1.42 meters (56 inches).