Critical Thermal Minima of age-0 Australian bass, Macquaria novemaculeata, fingerlings: implications for stocking programmes

Authors

  • L. M. CAMERON,

    1. Industry and Investment NSW, Grafton Fisheries Centre, Grafton, NSW, Australia and Marine Ecology Research Centre, School of Environmental Science and Management, Southern Cross University, Lismore, NSW, Australia
    Search for more papers by this author
  • L. J. BAUMGARTNER,

    1. Industry and Investment NSW, Narrandera Fisheries Centre, Narrandera, NSW, Australia
    Search for more papers by this author
  • D. J. BUCHER,

    1. Marine Ecology Research Centre, School of Environmental Science and Management, Southern Cross University, Lismore, NSW, Australia
    Search for more papers by this author
  • W. ROBINSON

    1. Industry and Investment NSW, Narrandera Fisheries Centre, Narrandera, NSW, Australia and Charles Sturt University, Albury, NSW, Australia
    Search for more papers by this author

Leo Cameron, Industry and Investment NSW, Grafton Fisheries Centre, PMB 2, Grafton, 2460 NSW, Australia (e-mail: leo.cameron@industry.nsw.gov.au)

Abstract

Abstract  Fishes are often stocked outside natural distribution ranges with inadequate information on target streams, particularly thermal regimes. Australian bass, Macquaria novemaculeata (Steindachner), is a catadromous species that is regularly stocked into upland reaches of rivers and impoundments in south-eastern Australia. Critical Thermal Minima (CTMin) were determined for age-0 Australian bass fingerlings with a mean fork length of 64.4 ± 0.4 mm and weighing 3.8 ± 0.8 g. Four treatments were used, including three replicate aquaria for each treatment. Fingerlings were acclimated at either 8 or 15 °C at densities of 15 fish in 56-L glass aquaria. Water temperatures were then decreased at either 1 °C day−1 or 1 °C h−1 until loss of equilibrium (LOE), which occurred between 3 and 7 °C. Mean CTMin among treatments was 3.22–4.64 °C and was influenced by acclimation temperature and rate of temperature decline. Fingerlings acclimated at 8 °C subjected to a temperature decline of 1 °C h−1 experienced highest LOE temperature. Post-LOE mortality among treatments was highest at 100% in the 8 °C acclimation with a 1 °C day−1 temperature decline. Mortalities following LOE occurred within 5 days. The results suggest that stocking age-0 Australian bass is unlikely to be successful in areas where winter temperatures fall below 6 °C.

Ancillary