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Species Synopses SAILFISH (Istiophorus platypterus) Sailfish have a tropical distribution which extends into subtropical waters of the Indian and Pacific Oceans. In the western Pacific they occur between 27°S and 40°N and in the east between 5°S-25°N. Peak concentrations in the Pacific occur around Papua New Guinea, Irian Jaya, the Caroline Islands, Solomon Islands and the East China Sea. Movements of sailfish tend to be more localised than those recorded for other species of billfish. Consequently, it appears that there are numerous isolated and semi-isolated stocks throughout their range. Sailfish on Australia's northeast coast tend to remain isolated between northern and southern locations, at least until fish reach maturity. Sailfish, in common with juvenile black marlin, spend considerable time in nearshore coastal waters, presumably to take advantage of the seasonal abundance of baitfish schools. On Australia's east coast, spawning is most likely among the coral reefs of the Great Barrier Reef over the summer months. In equatorial waters spawning occurs year-round. There are no external features to distinguish the sexes and, while it is generally believed that males and females reach equivalent weights, the larger fish are usually female. Sailfish may grow to 100kg with an average size of between 25 and 40kg. Off eastern Australia, males are not mature until they reach at least 20-25kg and females closer to 30-35kg. Presumed spawning activity on Australia's east coast is associated with fish generally in excess of 40kg. Size at maturity is similar in the East China Sea and even larger in the eastern Pacific. Little is known of their age and growth except evidence from a tagged and recaptured Atlantic sailfish estimated to be at least 15 years old. This does not, however, preclude the possibility of rapid growth during the first 10 years, as found for other species of billfish. There is a greater tendency amongst sailfish, in comparison to other billfishes, to form feeding aggregations. There are reports of cooperative feeding activity by up to 30-40 fish. Their diet appears to be considerably broader than for other billfishes, which may reflect their year-round predominance in coastal waters. In east coast Australia, herrings and pilchards are preferred but other fish, crustaceans and squid supplement this diet. web@aims.gov.au
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