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David Cooper from MTI and volunteers release bullies into Home Bay Stream MTI Director Paul Decker gets down to business Native fish return to MOTUTAPU ISLAND BY DAVID COOPER E arly on November 26, 100 native redfi n bullies, (Gobiomorphus huttoni) and 100 koura (Paranephrops planifrons) were removed from tanks at Mahurangi Technical Institute in Warkworth, where they had been living for several months, packed into plastic bags and polystyrene boxes, loaded in a van and driven down to Auckland. Thus began the introduction of these species to Motutapu Island in the Hauraki Gulf. It was the fi nal phase of a project that had been planned for many months. Their introduction was the brainchild of Callum Bourke, the Department of Conservation's freshwater ranger for the Auckland area. He had surveyed the streams on Motutapu Island and discovered they contain only four fi sh species: two species of eel, banded kokopu (Galaxias fasciatu)s and inanga (Galaxias maculatus). This was despite the fact that other species of freshwater fi sh are present on adjacent islands and nearby mainland sites and the stream habitat on Motutapu appeared to be suitable. Motutapu is being restored by the island's Restoration Trust in conjunction with DoC, and many streams have been fenced and planted with native riparian plants. There has been a measurable increase in the water quality over this time and it was decided the time was right to augment the depleted freshwater fauna, much as has been done with several bird species on the island. The Mahurangi Technical Institute was contracted to supply 100 redfi n bullies and 100 koura, with both species being a mixture of genders. The bullies were captured at various locations in the Auckland region over a period of months, while the koura were sourced from a commercial koura farm. Both species were held at the MTI aquaculture facility in Warkworth and conditioned to ensure they were free of disease and in the best possible condition for release. All were fed a natural diet while in captivity to ensure they recognised prey, and occasionally exposed to eels to ensure they could recognise predators. Both these issues have been shown in studies to severely affect the survival rates of captive fi sh when they are released. At 0730 on the day, the fi sh were delivered to Bayswater Marina and loaded aboard the DoC vessel Hauturu, along with about 40 volunteers from DoC, The Motutapu Island Restoration Trust, Mahurangi Technical Institute, Auckland Zoo, Afi shionado (an Auckland-based freshwater fi sh consultancy run by Paul Woodard) and representatives from Ngai Tai, the local iwi for the Island. After a brief stop in Auckland to collect more volunteers, they 14 ■ NZ AQUACULTURE ■ JANUARY/FEBRUARY 2012 Red-finned bully ( carried on to Motutapu, where Ngai Tai representatives formally welcomed them. The volunteers then split into four teams and set off for four different pre-selected locations on Home Bay Stream to release the fi sh. The koura were released directly into areas with lots of suitable stream cover. The bullies, after appropriate acclimation, were released into plastic bins fi tted with holes and mesh to allow water to fl ow through. These were placed in areas of moderate fl ow. Lids were fi tted to prevent the resident eels from dropping by for supper later and they were left until the next day, when Callum returned to release the bullies. This was done to allow the fi sh to acclimatise to the water conditions in a protected environment and hopefully maximise their chances of survival when released. Then it was back to Home Bay for a barbecue before returning home on the Hauturu. DoC staff will monitor the fi sh for 12 months and a further supplementary introduction of both species will take place at a similar time in 2012. MTI, as New Zealand's only commercial fi sh hatchery dealing in freshwater native fi sh, is looking to become more heavily involved in this type of conservation-related work and was delighted to collaborate with DoC on the project. The institute has supplied large giant kokopu (Galaxias argenteus) to a similar project in Orewa and on many occasions to zoos and public aquariums in New Zealand and internationally for display and to assist in educational programmes. Other non-native species bred at MTI include grass carp and silver carp, both of which are used widely for weed control, yet another environmental benefi t to come out of this innovative private training establishment, and of course the research project based on breeding shortfi n eels (Anguilla australis). Gobiomorphus huttoni) PHOTO: MAHURANGI TECHNICAL INSTITUTE Free at last!