Pacific Smalltail Shark, Carcharhinus cerdale
Pacific Smalltail Shark, Carcharhinus cerdale. Fish caught from coastal waters off Loreto, Baja California Sur, May 2019. Catch and photograph courtesy of Chris Wheaton, Fullerton, California.
The Pacific Smalltail Shark, Carcharhinus cerdale, is a member of the Requiem Shark or Carcharhinidae Family, and is known in Mexico as tiburónes poroso del Pacifico. For 60 years this fish was believed to be the Smalltail Shark, Carcharhinus porosus, but became a new stand alone species in 2011. Globally, there are thirty-five species in the genus Carcharhinus, of which seventeen are found in Mexican waters, seven in the Atlantic, four in the Pacific, and six in both the Atlantic and the Pacific Oceans.
The Pacific Smalltail Shark is a small shark with a slender fusiform body and a long, pointed snout. They are gray in color dorsally transitioning to white ventrally. The tips of the caudal, dorsal and pectoral fins may be dark tipped. Juveniles have a black edged caudal fin and pectoral fins with a wide white margin. Their head has large circular eyes and the mouth has broadly triangular front teeth with narrow, oblique, notched, and serrated points. Their first dorsal fin with low and bluntly pointed that originates over the rear inner margin of the pectoral fins; their second dorsal fin originates just behind the anal fin origin; and, their pectoral fins are small, slightly curved and are narrowly rounded with pointed tips. The have five gills that are found in front of the pectoral fins.
The Pacific Smalltail Shark is a demersal coastal species that is found over mud bottoms, including shallow estuaries at depths up to 12 m (40 feet). They reach a maximum of 1.4 m (4 feet 7 inches) in length. Their depth range has not been determined. They feed on fish, rays, juvenile sharks and small invertebrates. Reproduction is viviparous but specific details are lacking noting that the pups are born as miniature adults and left to fend for themselves. The Pacific Smalltail Shark 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.
The Pacific Smalltail Shark is a resident of Mexican waters of the Pacific Ocean but has a limited distribution being found in the Sea of Cortez and also south along the coast of the mainland to Guatemala. They are absent from along the West coast of Baja.
The Pacific Smalltail Shark is virtually identical to the Smalltail Shark, Carcharhinus porosus (Atlantic Ocean only species), with which it was confused with for 6 decades. They also resemble the much larger Bignose Shark, Carcharhinus altimus (first dorsal fin high; stout robust body), the Pacific Sharpnose Shark, Rhizoprionodon longurio (second dorsal fin origin before the anal fin), the much larger Narrowtooth Shark, Carcharhinus brachyurus (first dorsal fin high; blunt snout) and the much larger Silky Shark, Carcharinus falciformis (long pectoral fins).
From a conservation perspective the Pacific Smalltail Shark has not been formally evaluated and is currently listed as Data Deficient, with poorly documented and poorly studied populations. They are uncommon and believed to be harmless to human.