Critically Endangered
Smalleye hammerhead
Sphyrna tudes
Smalleye hammerhead is a shark or ray in the family Sphyrnidae (order Carcharhiniformes) — Sphyrna tudes, recorded as Critically Endangered.
Appearance
The second dorsal fin is smaller than the first, but still rather large, with a concave, trailing margin. The anal fin is taller and longer than the second dorsal fin. The caudal fin has a well-developed lower lobe and a notch near the tip of the upper lobe.
One of the smaller members of its family, the smalleye hammerhead can reach a length of 1.5 m (4.9 ft), though 1.2–1.3 m (3.9–4.3 ft) is more typical, and a weight of 9 kg (20 lb). The mallet-shaped cephalofoil is wide and long, with a span measuring 28–32% of the body length. The leading margin forms a broad arch with indentations in the middle and on either side.
Range and habitat
The smalleye hammerhead is found along the eastern coast of South America from Uruguay to Venezuela, though it seldom occurs further west than the Orinoco Delta southeast of Trinidad. This species inhabits inshore murky waters 5–40 m (16–131 ft) deep, over muddy bottoms. Segregation occurs by sex and age. Newborns and juveniles under 40 cm (16 in) long are found in the shallowest waters, moving deeper after a few months of life.
Pins are Wikidata “endemic to” fields. Orange dots, when present, are GBIF occurrence tiles — survey bias included.
Diet and breeding
Adult males and juveniles of both sexes form schools of uniform body size. These schools do not appear to relate to reproduction or migration. Adult females are apparently solitary.
Young smalleye hammerheads under 67 cm (26 in) long feed predominantly on penaeid shrimp, mostly Xiphopenaeus kroyeri. Larger sharks feed mainly on bony fishes, especially ariid sea catfish and their eggs.
In crisis
The golden color may serve to conceal it from predators such as larger sharks. Because of its abundance, the smalleye hammerhead is an economically important bycatch of artisanal gillnet fisheries throughout its range, and is used as food. In recent years, overfishing has caused marked declines in its numbers off Trinidad, northern Brazil, and probably elsewhere.
Coupled with the smalleye hammerhead's low reproductive rate, this led the International Union for Conservation of Nature to list the smalleye hammerhead as critically endangered in 2020.
Smalleye hammerhead is Critically Endangered on this catalog because that is the IUCN category stored on Wikidata. Confirm the official criteria and any later count on iucnredlist.org.
Sources
Written for this catalog from the English Wikipedia article on Smalleye hammerhead, Wikidata item Q1150019. Family and order context is original field-guide writing about the group, not a copied assessment of this one species. Wikipedia text is CC BY-SA. Not an IUCN assessment. Counts, when quoted, can change — confirm them on the recovery programme and on iucnredlist.org.
