Age and growth of Anguilla interioris leptocephali collected in Indonesian waters

Anguilla interiorisis has been only known to be distributed in northern New Guinea, but recent sampling surveys for leptocephali and the development of species identification techniques using DNA analysis have discovered that this species also appears to occur off Sumatra in the eastern Indian Ocean, and may be present in other areas of the Indonesian Archipelago. To reveal the ages and early life histories of this species, the otolith microstructure of the leptocephali collected near the Sulawesi Island and off Sumatra of Indonesia were examined. The otolith microstructure of the A. interioris leptocephali was similar to other anguillid species and showed narrow increment widths (0.49-0.58μm) near the core that increased (1.14-1.34μm) before decreasing again until the otolith edge (0.51-0.83μm), except in the smallest specimen (12.4mm TL) collected off Sumatra, which had no peak. The range of Sr: Ca ratios in their otoliths were 8.37 to 14.01. Their ages were 19d for the smallest specimen from off Sumatra, 85d for the specimen (48.9mm TL) from Tomini Bay, and 85 to 94d for the three specimens (43.4-46.5mm TL) from the Molucca Sea. The overall growth rate of the leptocephali was 0.48mm/d, and this value was intermediate compared with the growth rates of the other anguillid species. The age of the smallest A. interioris leptocephalus collected off Sumatra and the geographic patterns of currents in the regions, suggest that it was spawned in the Indian Ocean and that it may belong to a different population than the New Guinea population

Age and growth of Anguilla interioris leptocephali collected in Indonesian waters

Anguilla interiorisis has been only known to be distributed in northern New Guinea, but recent sampling surveys for leptocephali and the development of species identification techniques using DNA analysis have discovered that this species also appears to occur off Sumatra in the eastern Indian Ocean, and may be present in other areas of the Indonesian Archipelago. To reveal the ages and early life histories of this species, the otolith microstructure of the leptocephali collected near the Sulawesi Island and off Sumatra of Indonesia were examined. The otolith microstructure of the A. interioris leptocephali was similar to other anguillid species and showed narrow increment widths (0.49-0.58μm) near the core that increased (1.14-1.34μm) before decreasing again until the otolith edge (0.51-0.83μm), except in the smallest specimen (12.4mm TL) collected off Sumatra, which had no peak. The range of Sr: Ca ratios in their otoliths were 8.37 to 14.01. Their ages were 19d for the smallest specimen from off Sumatra, 85d for the specimen (48.9mm TL) from Tomini Bay, and 85 to 94d for the three specimens (43.4-46.5mm TL) from the Molucca Sea. The overall growth rate of the leptocephali was 0.48mm/d, and this value was intermediate compared with the growth rates of the other anguillid species. The age of the smallest A. interioris leptocephalus collected off Sumatra and the geographic patterns of currents in the regions, suggest that it was spawned in the Indian Ocean and that it may belong to a different population than the New Guinea population