Whitenose Shark, Nasolamia velox
The Whitenose Shark, Nasolamia velox, whose common Spanish name is tiburón coyotito, is a member of the Requiem Shark or Carcharhinidae Family, known collectively as tiburónes gambuso in Mexico. Globally, this fish is the only species in the genus Nasolamia and it is found in Mexican oceanic waters of the Pacific.
The Whitenose Sharks have slender bodies with a very long conical snout. They are uniformly brownish-gray with metallic hues dorsally and transition to white ventrally. Their second dorsal fin has a dusky tip. Their anal fin is slightly larger than their second dorsal fin and has a deeply notched posterior margin. Their caudal fin is asymmetrical and curved with an upper lobe that is notched under the tip and a large lower lobe. Their first dorsal fin originates over the free tips at the rear of the pectoral fins. Their second dorsal fin is smaller than the first with a height that is about one-third the height of the first dorsal fin and originates over the anal fin. Their pectoral fins are broad, triangular, and slightly falcate and originate over the third gill slit. Their head is very narrow and conical with a pointed snout this is much longer that the width of the mouth. They have large eyes with a small vertical pupil. Their nostrils are very large, transverse, oval, and close set and are located midway between the tip of the snout and the front of the mouth. Their upper jaw has 27 to 30 strongly oblique cusps with a strong notch on the outer margins, finely serrated edges, and overlapping bases. Their lower jaw has 25 to 27 slender, narrow, finely serrated, non-protruding teeth set it rows. They lack the traditional ridge between the dorsal fins or keels on the caudal peduncle that are found in other similar sharks. They have 5 gill slits with the last two being over the pectoral fins.
The Whitenose Sharks are uncommon and found demersal both inshore and offshore over the continental shelf at depths between 80 and 600 feet. They reach a maximum length of 1.65 meters (5 feet 5 inches). They feed on small fish such as anchovies and invertebrates such as crabs. Reproduction is viviparous with litter sizes between five and six 50 cm (20 inch) to 55 cm (22 inch) pups. They are poorly studied and very little is known about their population trends and behavioral patterns.
In Mexican waters the Whitenose Sharks are found in all waters of the Pacific with the exception of Guerrero Negro northward along the central and northwest coasts of Baja. They are infrequent visitors to the Baja and only found during warm water episodes; they are known to congregate at certain times of the year in coastal waters off Puerto Madero, Chiapas.
The Whitenose Shark is most likely confused with the Blue Shark, Prionace glauca (dorsal fin posterior originating well behind free tips of pectoral fins) and the Pacific Sharpnose Shark, Rhizoprionodon longurio (pronounced labial furrows; more widely spaced nostrils; second dorsal fin originating well behind anal fin origin).
The Whitenose Sharks are caught on a limited basis as a by-catch of artisanal fishermen utilizing longlines and gill nets. They are used as food for local consumption and in fish meal whereas their fins are exported to Asia. From a conservation perspective they are listed as Data Deficient due to their rarity. Of concern are the inshore fishing pressure, human destructive trawling practices, water pollution, and coastal sedimentation that all have an adverse effect on their coastal nursery grounds. They are not currently protected by any form of management measures. There have been no documented attacks on humans by Whitenose Sharks.
Whitenose Shark, Nasolamia velox. Fish caught in coastal waters north of Puerto Los Cabos, Baja California Sur, June 2007. Length: 1.07 meters (3 feet 6 inches). Identification courtesy of Dr. Ross Robertson, Smithsonian Tropical Research Institute, Panama.