Florida Smoothhound, Mustelus norrisi
Florida Smoothhound, Mustelus norrisi. Fish caught out of 450-foot water on the Golden Grounds, 150 miles west of Tarpon Springs, Florida, December 2013. Length: 1.37 m (4 feet 6 inches). Catch, photograph, and identification courtesy of George Brinkman, Guelph, Ontario, Canada.
The Florida Smoothhound, Mustelus norrisi, is member of the Hound Shark or Triakidae Family, that is also known as the Narrowfin Smoothhound and in Mexico as cazón viuda. 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 Florida Smoothhound has an elongated and slender body. They are uniform gray to gray-brown dorsally and transition to creamy white ventrally without additional spots or markings on their body. Some fish have fins with pale edges. In juveniles, the tips of the caudal and dorsal fins are dusky. Their head is short, narrow, and flattened ventrally. They have a short pointed snout, large oval eyes, and a prominent spiracle immediately behind each eye. Their mouth is long with the upper and lower lip folds being of equal length. Their teeth are low stumpy cusps set in 60 to 65 rows on the upper jaw and 55 to 60 rows on the angular lower jaw. Their nostrils are widely spaced. Their caudal fin is asymmetrical with a prominent hook and pointed lower lobe directed backwards. They have 2 large dorsal fins with rounded tips and concave rear margins: the first dorsal fin originates over or behind the rear base of the pectoral fins; the second dorsal fin, which is about 75% as high as the first dorsal fin, originates before the anal fin. Their anal and pelvic fins are much smaller than the second dorsal fin; their dorsal fins are falcate with serrated trailing edges; and, their pectoral fins are small but long and thin with pointed tips. They have 5 gill slits with the last 2 located over the pectoral fins. They have overlapping single-pointed denticles with two converging ridges.
The Florida Smoothhound is found inshore over sandy and muddy bottoms at depths up to 88 m (290 feet). They reach a maximum length of 1.10 m (3 feet 6 inches) and 13.8 kg (30 lbs 13 oz) in weight with females being larger than males. As of January 1, 2024, the International Game Fish Association world record stood at 13.78 kg (30 lbs 6 oz) with the fish caught in coastal waters off Destin, Florida in April 1992. Depending on location they are either densely populated or sparse throughout their wide range and are known to segregate by size. They are migratory moving to inshore shallower waters during the winter months and returning offshore during the summer months. They feed on crabs, fish and shrimp. In turn they are preyed upon by the Blacktip Shark, Carcharhinus limbatus, the Dusky Shark, Carcharhinus obscurus, and the Great Hammerhead, Sphyrna mokarran. Reproduction is viviparous with embryos being nourished via a yolk sac then a yolk sac placenta while developing inside the mother’s body. Each litter has seven to fourteen miniature adults which measure approximately 30 cm (12 inches) in length. The Florida 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.
The Florida Smoothhound is a resident of all Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the east coast of the Yucatán Peninsula in the Caribbean.
The Florida Smoothhound is very similar to, and easily confused with, the Smooth Dogfish, Mustelus canis (much wider gap between nostrils; caudal fin with rounded lower lobe). It can also be confused with the Gulf Smoothhound, Mustelus sinusmexicanus (caudal fin lacking lower lobe). Based on genetic analysis, some believe the Florida Smoothhound and the Smooth Dogfish are one and the same species.
From a conservation perspective the Florida Smoothhound is currently considered to be Data Deficient with poorly documented populations. Although they have moderate fecundity levels, they are targeted by commercial fisherman at a small level. They are very accessible due to their inshore habitats and are a by-catch of the trawl industry at unknown levels. They are known to contain high levels of mercury. There is concern that they will follow in the footsteps of the Striped Smoothhound, Mustelus fasciatus, which has been fished to near extinction in southern Brazil due to intense gill net pressure on their inshore habitat. 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. This species is considered harmless to humans.