New Zealand Journal of Marine and Freshwater Research abstracts
Causes of tail fan necrosis in the southern rock lobster, Jasus edwardsii
Richard J. Musgrove
South Australian Research and Development
Institute (Aquatic Sciences)
P.O. Box 120, Henley Beach
SA 5024, Australia
email: musgrove.richard@saugov.sa.gov.au
Michael C. Geddes
School of Earth and Environmental Sciences
The University of Adelaide
SA 5005, Australia
Connor Thomas
School of Molecular and Biomedical Science
The University of Adelaide
SA 5005, Australia
Abstract Tail fan necrosis (TFN) is a recognised constraint
on the advancement of the South Australian rock lobster (Jasus edwardsii)
liveholding industry because of a reduction in value of afflicted lobsters.
Trials were run in the laboratory and at a shore-based experimental live-holding
facility (LHF) to determine the influence of at-sea post-harvest handling,
feeding frequency (LHF only), density (LHF only), and temperature (laboratory
only) on the advent of the condition. Lobsters were caught during normal
fishing operations and either immediately placed in protective fine-mesh
nylon bags and stored in the boat’s well or placed unbagged in the well.
At the laboratory, the tail fans of half the bagged lobsters were deliberately
damaged with sterile instruments. At the LHF the TFN level increased significantly
over 4 months. The bagged treatment showed significantly less late-stage
TFN than unbagged daily or weekly-fed treatments with 60% of bagged lobsters
showing no TFN at 4 months. With unbagged lobsters, 50% showed erosion in
the <25% category and 30% showed erosion of >25% of the tail fan. Lobster
density and feeding frequency had no effect on TFN incidence. In the laboratory,
bagged and bagged-damaged treatments had no advanced TFN after the 6-week
period suggesting that post-harvest bagging minimises TFN and that inflicting
physical damage to lobster tail fans with aseptic instruments does not lead
to its development. Temperature had no effect on TFN development. The highest
incidence of TFN was found in lobsters given normal post-harvest handling,
that is, communal holding in boat holds and tanks (i.e., without bags). These
conditions are normally associated with physical damage inflicted by conspecifics.
Such damage will presumably also involve infection of wounds by the bacterial
flora of the crayfish exoskeleton, leading to development of TFN.
Keywords southern rock lobster; Jasus edwardsii;
tail rot; tail fan necrosis; liveholding; Vibrio
M04006; Online publication date 31 May 2005 Received 8 February 2004;
accepted 8 July 2004
New Zealand Journal of Marine and Freshwater Research, 2005, Vol. 39:
293-304
0028-8330/05/3902-0293 © The Royal Society of New Zealand 2005
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