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Radio-tagging and tracking of translocated trout cod (Maccullochella macquariensis: Percichthyidae) in an upland river

Ebner, B.C., Johnston, L., Lintermans, M.
Marine & freshwater research 2009 v.60 no.4 pp. 346-355
Maccullochella macquariensis, adults, aquariums, cod (fish), diel activity, habitats, highlands, males, monitoring, radio frequency identification, radio telemetry, rivers, streams, survival rate
Radio-tracking provides an effective means of studying the spatial ecology of threatened fishes where almost inaccessible habitats and species rarity render conventional mark-recapture methods impractical. Initially, validation of an effective radio-tagging method is required; in the present study, an aquaria trial based on nine hatchery-reared, adult male Maccullochella maquariensis (Percichthyidae) was conducted. Fish resumed feeding within days of being internally implanted with a radio-tag, and tag rejection was not observed (0%, n = 9) based on a 2-month observational period. Following release into an upland stream, individual-specific movements resulted in upstream (n = 1) and downstream (n = 6) dispersal as well as fidelity to the release site (n = 2) at the completion of the study. Individuals established small home-ranges (mean length of river used by an individual per diel period ranged from 47 to 292 m) and were most active in the early morning and evening (n = 6). Complete survivorship of individuals bearing active radio-transmitters (n = 8) was recorded up until 4 months after release. However, an estimated zero or one individual was alive when the last active radio-tag expired 11 months after release (n = 8). The present study highlights the use of radio-tracking in monitoring the dispersal and survivorship of small numbers of hatchery-reared threatened fish released into natural habitats as part of species re-introduction programs.