Shallow-Water Fishes of Walters Shoals, Madagascar Ridge

Walters Shoals is an isolated seamount reaching to within 18 m of the surface, and is located about 400 nautical miles south of Madagascar and 600 nm east of South Africa. It is part of a chain of seven islands and seamounts extending along the West Wind Drift from Gough and Tristan da Cunha in the South Atlantic to Amsterdam and St. Paul in the southern Indian Ocean. Fishes were collected during VITYAZ cruise 17 in December 1988. The shallow-water fish fauna comprises about 20 species and is composed of three elements: endemics (7–8 species), wide-spread temperate or subtropical species (5–6), and tropical Indo-West Pacific reef species (6). Three species, a carangid, Trachurus longimanus, a cheilodactylid, Acantholatris monodactylus, and a labrid, Nelabrichthys ornatus, are endemic to the West Wind Drift islands. A serranid, Lepidoperca coatsii, is known from four of the island groups and may also occur at Walters Shoals. Another serranid, Serranus novemcinctus, occurs only at the four Indian Ocean islands and seamounts. The common Gymnothorax is an undescribed species, probably endemic. A specimen of scorpaenid has been described as Scorpaenodes immaculatus, also probably endemic. A second species of Gymnothorax and the species of Plagiogeneion may also be endemic species. Thus, 30–40% of the shallow water fish fauna of Walters Shoals is endemic to some part of this chain of islands and seamounts. The species of Carcharhinus, Cheilopogon, Polyprion, Seriola, and Scomber are wide-spread in temperate or subtropical waters. Plectranthias longimanus, Apogon semiornatus, Chromis weberi, C. axillaris. Pterois cf. miles, and Kentrocapros rosapinto are tropical Indo-West Pacific reef fishes. The fish fauna of Walters Shoals links Briggs's Tristan-Gough Province of his southern South America Cold Temperate Region with the Amsterdam-St. Paul Province of his Southern African Warm Temperate Region into a single zoogeographic province, which is here called the West Wind Drift Islands Province.