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Biological feasibility of spiny lobster Jasus edqardsii stock enhancement

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Oliver, Megan Dianne 2007 , 'Biological feasibility of spiny lobster Jasus edqardsii stock enhancement', PhD thesis, University of Tasmania.

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Abstract

The highly valued spiny lobster or southern rock lobster (Jasus
edwardsil) found in South Australia, Tasmania and New Zealand
presents a challenging candidate for aquaculture and stock
enhancement efforts. Despite their gregarious nature and high survival
in captivity, the protracted larval phase makes commercial-scale
hatchery production of seed unfeasible. Therefore, the recently settled
juvenile stage, or puerulus, must be trapped in the wild for on-growing
in captivity. This puerulus harvest effectively increases exploitation and
the conditions of harvest dictate that a proportion of juveniles must be
returned to the wild after one year to maintain biological neutrality.
Maintaining animals in captivity for lengthy periods, however, can
disrupt behavioural development and contribute to high mortality after
release into the wild. Research presented here investigates the
influence captivity has on the pre- and post-release behaviour of
juvenile spiny lobsters and how this may impact the success of
reseeding efforts and the related goal of increasing productivity through
stock enhancement.
Juvenile lobsters reared in captivity without predators and fed by day
displayed significantly higher levels of daytime activity than their wild
counterparts. This behaviour could be manipulated with the addition of
predators or night time feeding. Neither training method was necessary,
however, because released lobsters resumed normal nocturnal activity
and displayed appropriate anti-predator behaviour.
Tethering experiments found predation was greatest in the first two
hours after release and in the crepuscular period of the following
morning. High predation was likely caused by the attraction of diver
positive fish species during release and high predator activity during
crepuscular periods.
Midnight observations of foraging distances and acoustic tracking over
successive days, found that released lobsters moved similar distances
to like-sized wild lobsters and recorded a strong association between
den or area fidelity and the presence of conspecifics.
Preliminary tank-based experiments to determine the potential for
displacement of wild lobsters by released lobsters found that although
released lobsters displayed a significant preference for crowding into
the same dens as wild animals, disturbance of wild lobsters was
minimal.
Behavioural changes induced by on-growing in captivity do not appear
to influence post-release behaviour or survival. Refined release
protocols are likely to substantially reduce initial predation and increase
site fidelity where there is an abundance of suitable habitat on
contiguous reef. The overall conclusion is that reseeding to
compensate for puerulus harvest should lead to enhancement of wild
populations with concurrent investigation and improvement of release
protocols.

Item Type: Thesis - PhD
Authors/Creators:Oliver, Megan Dianne
Keywords: Jasus edwardsii, Spiny lobsters, Lobster fisheries, Spiny lobster industry, Jasus edwardsii, Spiny lobsters
Copyright Holders: The Author
Copyright Information:

Copyright 2007 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:

Available for library use only and copying in accordance with the Copyright Act 1968, as amended. Thesis (PhD)--University of Tasmania, 2007. Includes bibliographical references. Ch. 1. General introduction -- Ch. 2. Emergence behaviour of captive-reared juvenile lobsters pre- and post-release -- Ch. 3. Anti-predator behaviour of captive-reared and wild juvenile lobsters -- Ch. 4. Timing of predation on captive-reared juvenile lobsters immediately after release -- Ch. 5. Patterns of residency and foraging of wild and captive-reared juvenile lobsters on a shallow coastal reef -- Ch. 6. Den fidelity and short-term movement patterns of captive-reared and wild juvenile lobsters immediately after release -- Ch. 7. Competitiion for shelter between captive-reared and wild juvenile lobsters -- Ch. 8. General discussion

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