GRUBER and COMPAC.NO; TAXONOMIC STATUS AND BIOI.OCV UF lilCKYK TllRESHKR 



Alopias superciliosus is both neritic and pelag- 

 ic. Kato et al. (1967) and S. Kato (footnote 8) 

 noted that the bigeye thresher is commonly 

 caught on high-seas longlines far from land, but 

 capture data in Cadenat (1956), Strasburg (1958), 

 Fitch and Craig (1964), Osipov (1968), Guitart 

 Manday (1975), and Stillwell and Casey 

 (1976) indicate that concentrations of the species 

 commonly occur near land and that it occasionally 

 enters coastal and even shallow waters. It also 

 occurs near the bottom in relatively deep water 

 (Nakamura 1935; Fitch and Craig 1964), has 

 been captured at the surface offshore (the Miami 

 specimen), and is known to range to a depth of 

 about 500 m. Prey items taken from stomachs of 

 the bigeye thresher include both midwater and 

 benthic species indicating the habitats visited by 

 the shark (see below for details). 



Figure 14 is a map of the known distribution of 

 A. superciliosus. including approximate numbers 

 collected. The range as presently known includes 

 the western North Atlantic from off New York to 

 Florida, the Bahamas, Cuba, and the Caribbean to 

 at least Venezuela (Springer 1943; Bigelow and 

 Schroeder 1948; Fitch and Craig 1964; Mago L. 

 1970; Schwartz and Burgess 1975; Stillwell and 



Casey 1976; Compagno 1978). It occurs in the 

 western South Atlantic from off southern Brazil 

 (Sadowsky and Amorim 1977); the eastern Atlan- 

 tic from off Portugal, Madeira, Senegal, possibly 

 Guinea or Sierra Leone, Angola, and the Mediter- 

 ranean (Lowe 1840; Cadenat 1956, 1961; Williams 

 1968; Telles 1970; and authors' specimens); the 

 western Indian Ocean from off South Africa, 

 Madagascar, and the Arabian Sea (Fourmanoir 

 1963; Osipov 1968; Gubanov 1972; Bass et al. 

 1975); the western Pacific from off Taiwan, pos- 

 sibly Japan, New Caledonia, and New Zealand 

 (Grey 1928; Nakamura 1935; Fourmanoir 

 and Rancurel 1972; and authors' specimens); the 

 central Pacific, north and south of the Hawaiian 

 Islands and between Panama and the Marquesas 

 Islands (Strasburg 1958; S. Kato footnote 8); and 

 the eastern Pacific from off southern California 

 (Fitch and Craig 1964) and in the Gulf of Califor- 

 nia ( Applegate et al. 1979). 



REPRODUCTION 



Intrauterine development in thresher sharks 

 is ovoviviparous. As in the lamnids and odon- 

 taspidids, fetal bigeye threshers are apparently 



Figure 14.— Distribution of Alopias superciliosus. The 16 filled circles represent stations where fewer than 10 bigeye threshers were 

 collected. The four filled squares show stations where this shark has been taken in commercial numbers. Several more Bahamian 

 locales reported by the U.S. National Marme Fisheries Service were not included because the scale on the map is too coarse. This chart 

 does not include much of the Soviet or Japanese longline catch, but extends the knowTi di.stributon of A. superciliosus to the 

 Mediterranean and New Zealand. 



633 



