New Zealand Journal of Marine and Freshwater Research abstracts
Stock enhancement of rock lobsters (Jasus edwardsii): timing of
predation on naïve juvenile lobsters immediately after release
Megan D. Oliver1
Rob Stewart1
David Mills2
Alison B. MacDiarmid1
Caleb Gardner2
1 National Institute of Water and Atmospheric
Research Limited
Private Bag 14901
Wellington, New Zealand
email: m.oliver@niwa.co.nz
2 Tasmanian Aquaculture and Fisheries Institute (TAFI)
GPO Box 25249, Hobart
TAS 7007, Australia
Abstract The success of enhancement programmes hinges
on the survival of released animals. One factor greatly influencing short-term
survival of reseeded lobsters is the timing and intensity of predation relative
to the time of release. The activity and abundance of predators varies over
daily, seasonal, and annual scales and knowing the best time to release juveniles
will minimise mortality. We used chronographic tethering devices and remote
video equipment at 10 sites near Wellington, New Zealand and Hobart, Tasmania,
Australia, to assess the relative timing and intensity of predation for released
lobsters. Our studies showed that predation was greatest within the first
2 h after release (chi2 = 60.425, d.f. = 9, P < 0.001) suggesting
that the disturbance associated with the release itself may draw the unwanted
attention of predators. Relative predation rates also peaked on each of the
following two mornings, possibly because of the emergence of daytime predators.
The video footage obtained at the Tasmanian sites revealed that most predation
was by fish (46%), but surprisingly, cannibalism comprised 16% of predation
events. The limitations of tethering as a method are discussed in numerous
reviews but proved useful as a relative measure for these highly mobile and
cryptic animals. Further consideration needs to be given to methods of release
that minimise mortality of recently seeded lobsters.
Keywords rock lobster; Jasus edwardsii; tethering;
relative predation; stock enhancement
M04041; Online publication date 31 May 2005 Received 10 February 2004;
accepted 14 May 2004
New Zealand Journal of Marine and Freshwater Research, 2005, Vol. 39:
391-397
0028-8330/05/3902-0391 © The Royal Society of New Zealand 2005
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