About the Species
The narrownose smoothhound is a shark. It is the most abundant and widely distributed Triakid in the Argentine Sea and historically had high densities in the Argentine-Uruguay Common Fishing Zone. However, due to significant fishing pressure by commercial and artisanal fisheries throughout its range, the species has experienced potentially significant population declines and the potential extirpation of its breeding population in Brazil. The main threat to the narrownose smoothhound is targeted and incidental catch in various commercial and artisanal fisheries operating in its coastal inshore habitat, including nursery areas. In 2017, NOAA Fisheries listed the species as threatened under the Endangered Species Act.
Appearance
The narrownose smoothhound shark has a slender body, similar in form to other triakids, and a short head with large eyes. The snout is bluntly angular and there is narrow distance between nostrils. Narrownose smoothhounds are gray with numerous small white spots on their dorsal side and solid white coloration underneath. The trailing edges of both dorsal fins have exposed ceratotrichia (slender soft or stiff filaments of an elastic protein that superficially resembles keratin), a distinctive characteristic for the species.
Behavior and Diet
The narrownose smoothhound is an opportunistic predator that generally feeds on epifaunal benthic organisms (e.g., crustaceans, decapod crabs, fishes, polychaetes) and the diet appears to vary both geographically and throughout development.
Where They Live
The narrownose smoothhound is found in the southwestern Atlantic from southern Brazil to southern Argentina between 22° S. and 47°45′ S, with Rio de Janeiro, Brazil being the northernmost limit of the species’ range and Deseado, Argentina being the southernmost limit. Narrownose smoothhounds have been observed as deep as 640 feet in Brazil and occur in temperatures of 42 °F to 53 °F. In the spring, summer, and autumn (December to April), narrownose smoothhounds are most common in waters off Uruguay and Argentina.
World map providing approximate representation of the narrownose smoothhound shark's range.
Lifespan & Reproduction
Female narrownose smoothhounds have an estimated lifespan of up to 25 years, whereas males live to approximately 21 years. Narrownose smoothhound sharks have an annual reproductive cycle with a gestation of 11 months, followed by immediate ovulation and mating. Females move inshore to pup and mate in the spring, and then migrate offshore in late summer to early autumn. Reproduction occurs at different times, ranging from late November in northern Argentina to mid-December at the southern extent of its range. Litter size varies between 2 and 14 pups with an average litter size of around 4 to 5 pups, and increases significantly with maternal length.
Threats
Overfishing
The primary threat to the narrownose smoothhound is ovefishing in commercial and artisanal fisheries. The narrownose smoothhound is intensely fished throughout its entire range (including within its nursery grounds), both as targeted and incidental catch. It is the most heavily exploited species of shark in the Argentine-Uruguay Common Fishing Zone with population declines observed. Additionally, intensive fishing by industrial and artisanal fleets may have also resulted in the extirpation of the local breeding population in southern Brazil. The species continues to experience high levels of fishing mortality because of high fishing effort throughout its range, particularly within the important coastal nursery and inner shelf habitats for the species.
Scientific Classification
| Animalia |
Chordata |
Chondrichthyes |
Carcharhiniformes |
Triakidae |
Mustelus |
schmitti |
Last updated by NOAA Fisheries on 10/30/2023
