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Physiological responses of bluethroat wrasse, Notolabrus tetricus, horseshoe leatherjacket, Meuschenia hippocrepis and greenback flounder, Rhombosolea tapirina, to low temperature transport

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Findlay, JD (2005) Physiological responses of bluethroat wrasse, Notolabrus tetricus, horseshoe leatherjacket, Meuschenia hippocrepis and greenback flounder, Rhombosolea tapirina, to low temperature transport. PhD thesis, University of Tasmania.

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Abstract

The study reviewed the techniques used in the global trade of live fish. Based on this
review and field and laboratory experiments, methods were identified to improve the
survival of bluethroat wrasse, Notolabrus tetricus, horseshoe leatherjacket, Meuschenia
hippocrepis and greenback flounder, Rhombosolea tapirina, during capture, holding and
transport. Investigation of the physiological responses of fish exposed to lowered
temperatures was a central theme including description of cold thermal tolerance and the
effects of lowered temperature on oxygen consumption.
The Critical Thermal Minima and Incipient Lethal Temperature were determined for
bluethroat wrasse and greenback flounder. Greenback flounder exhibited remarkable
thermal tolerance with a TL 50(24hr) of 2.3°C (acclimation temperature 15 °C).
A flow-through respirometer was used to measure oxygen consumption. Bluethroat
wrasse exhibited 20% greater oxygen consumption than greenback flounder under
normoxic conditions. In both species, a reduction in temperature of 10°C more than
halved the oxygen consumption as predicted by typical biological Q1o values.
Greenback flounder maintained or increased oxygen consumption during graded hypoxia
(i.e. a non-conformer) and exhibited a critical oxygen tension of less than 25% oxygen in
air-saturated seawater. Oxygen consumption of bluethroat wrasse decreased during
graded hypoxia (i.e. a conformer) but no significant increase in blood lactate
concentration was observed.
Lowered temperatures induced and maintained coma in horseshoe leatherjackets and
bluethroat wrasse, however mean coma-inducing temperatures were generally <0.5°C
higher than the TL50. The induction of coma in bluethroat wrasse did not significantly
reduce oxygen consumption beyond the level predicted by temperature alone and did not
result in a significant increase in blood lactate. The risk of exceeding thermal tolerance
when applying coma-inducing temperatures needs to be carefully assessed before use. Feeding history had a marked impact on thermal tolerance. Greenback flounder deprived
of food for 72hr exhibited greater than 90% survival when exposed to temperatures of
3°C whereas fish deprived of food for only 24hr exhibited less than 10% survival at the
same low temperature. The magnitude of specific dynamic action (SDA) in greenback flounder was 1.88 times higher than the routine rate of oxygen consumption and total
duration was 52hr at 15°C.
Oxygen extraction by bluethroat wrasse was significantly reduced during lowered
temperature and hypoxia. The ventilation rate and ventilation stroke volume of
bluethroat wrasse generally decreased with lowered temperature and afferent oxygen
tension.
The study demonstrated that food deprivation and temperature reduction are powerful
tools to improve the survival of fish during transport.

Item Type: Thesis (PhD)
Keywords: Fishes, Temperature
Copyright Holders: The Author
Copyright Information:

Copyright 2005 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 2005. Includes bibliographical references

Date Deposited: 09 Dec 2014 00:10
Last Modified: 11 Mar 2016 05:54
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