Ebner, B. C., and Thiem, J. D. (2009) Monitoring by telemetry reveals differences in movement and survival following hatchery or wild rearing of an endangered fish. Marine and Freshwater Research, 60 (1). pp. 45-57.

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Abstract

Species reintroduction is a management strategy used to conserve endemic fish biodiversity. The present study investigated stocking on-grown endangered trout cod (Maccullochella macquariensis) in the Murrumbidgee River, Australia. The hypothesis that post-juvenile dispersal underpins the long-term scarcity of adults recorded at fingerling stocking locations was also tested. Radio-trackingwas used to quantify dispersal of stocked sub-adults (2-year old hatchery fish, n=27) compared with fish originally stocked as fingerlings (unknown-age wild fish, n=31), but we encountered poor survivorship of the former group (survivorship=9% and 95%, respectively, at 13 months post release). The hatchery group exhibited both limited dispersal and large-scale dispersal (up to 55 km) downstream from the release site. Wild fish exhibited limited net dispersal, occupying home-ranges within a 13-km reach and occasionally undertook large-scale excursions (10-70 km). It is concluded that (1) re-establishment of cod populations based on release of on-grown fish is not straightforward, and (2) adults of this species have an ability to disperse away from stocking sites. The study demonstrates the benefit of using radio-tracking to monitor the movement and survivorship of stocked threatened fish and indicates a need to consider the effects of hatchery rearing when conducting fish reintroductions.

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