The ecology of and fishery for Coryphaena spp. in the waters around Australia and New Zealand

Two species of dolphinfish, Coryphaena hippurus and Coryphaena equiselis, a re found in Australian waters and off the north-eastern coast of New Zealan d. Both species (also called Mahi-mahi, or dorado) are generally found in t ropical waters, but only C. hippurus is captured in southern waters (to 34 degrees S). Dolphinfish are caught by recreational and commercial fishers, using either trolled or baited lines. Most catch records do not allow the i dentification of fish to the species level. Dolphinfish are also an inciden tal catch of foreign and domestic pelagic fisheries (e.g. long-lining for t unas and billfishes) and 10-70 tonnes are taken per year in the Australia-N ew Zealand region. Although Coryphaena are known to associate with objects (e.g. traps for carangids and navigation buoys) and are a focus for recreat ional fishers, Fish Attraction Devices (FADs) are not used by commercial fi shers off the coast of Australia and New Zealand. FADs are, however, used b y fishers in the Pacific Islands. Recreational catches of Coryphaena may ex ceed the commercial catch in some areas. Good data for New South Wales, Aus tralia, gave estimates of 11.7 and 12.7 tonnes of Coryphaena caught in 1994 and 1995 respectively, which represented 1.1-1.8x the recorded commercial catch. Approximately similar to 12,600 fish have been tagged since 1973 aro und Australia and data on returns are only available for 108 fish (0.86% re covery). Tagged Coryphaena were found to move distances of up to 440 kilome tres and at estimated speeds of up to 20 kilometres per day. The time betwe en tag and recapture varied from 0-360 days and fish moved 0-440 kilometres . The majority of fish were caught around the same drifting object near whe re they were tagged. The collection of Coryphaena larvae in Queensland and New South Wales, along the east coast of Australia, indicates spawning in t hese waters. Most larvae have been collected in the austral summer and autu mn and typically in surface waters well offshore. Dolphinfish have been suc cessfully raised from eggs to fish of marketable size in Western Australia and the species appears to be an excellent candidate for mass production, w hich is now possible in Australia.