Biological observations on lamnoid sharks (Lamniformes) caught by fisheries in eastern Indonesia

Abstract

Fish landing site surveys in eastern Indonesia, conducted between April 2001 and March 2006, recorded seven species of lamnoid sharks (order Lamniformes) belonging to four families. Of these, Alopiidae were most abundant in the landings, with Alopias pelagicus contributing ~13% to the total biomass of all sharks recorded. Single specimens of both Carcharias taurus and Odontaspis ferox represent the first confirmed records of these two odontaspid species from Indonesian waters. The length at first maturity (L₅₀) of females and males of Alopias pelagicus were 2853 and 2468 mm total length (TL), respectively, and size at birth was 1300–1440 mm TL. Pregnant females of both A. pelagicus and A. superciliosus had litters of only two embryos (one per uterus) that were confirmed to be oophagous, but not adelphophagous. Females and males of Pseudocarcharias kamoharai matured at 870–1030 and ~725 mm TL, respectively, and size at birth was 360–450 mm TL. Pregnant females contained four embryos (two per uterus) which were oophagous, but unlikely to be adelphophagous. Males of Isurus oxyrinchus and I. paucus matured at ~1860 and 2050– 2281 mm TL, respectively. These are the first biological data reported on lamnoid sharks in Indonesian waters.