New Zealand Journal of Marine and Freshwater Research abstracts
Characterising shelter preferences in captive juvenile Jasus edwardsii
(Palinuridae)
John D. Booth
Dieter Ayers
National Institute of Water and Atmospheric
Research Limited
P.O. Box 14 901
Wellington, New Zealand
email: j.booth@niwa.co.nz
Abstract Any attempt to enhance rock lobster production
by increasing survival after settlement, or by ongrowing or outplanting young
juveniles, requires knowledge of the shelter preferences of young juveniles.
For juvenile Jasus edwardsii in the wild these are not well known.
Information available suggests that juveniles up to c. 35 mm carapace length
(CL) occupy shelters that generally conform closely to their body dimensions
but that larger juveniles use shelters of more variable dimension, often much
larger than their body size. We investigated mainly physical factors important
in shelter choice by 15-59 mm CL (c. 2-24-month-old juveniles) in laboratory
tank experiments. In overnight tests, all sizes of juvenile lobster chose
to occupy holes (shelters with sides) over open horizontal gaps. Preference
for open horizontal gaps versus horizontal crevices (where the height reduces
from a maximum at the mouth to zero at the opposite end) was much less clear-cut;
choice varied according to lobster size. For the number of entrances into
holes, there was evidence for an ontogenetic shift in preference, small lobsters
preferring two openings over one, whereas those >30 mm CL (c. 9 months
old) preferred one over two. For lobsters <40 mm CL, the hole size and
gap size preferences revealed were generally consistent with the field evidence
for J. edwardsii in that there was a close and proportional relationship
between lobster size and shelter size; what differed was that the open gaps
chosen in the tanks by the smallest lobsters (15-19 mm CL) were larger than
the holes used in the tank experiments and 30-50% larger than those reportedly
used in the field. For lobsters >40 mm CL, the holes and gaps chosen in
the tanks were generally larger and more variable in size, as in the field.
Keywords palinurid; rock lobster; Jasus edwardsii;
juvenile; habitat preference; enhancement
M04064; Online publication date 31 May 2005 Received 23 March 2004; accepted
13 September 2004
New Zealand Journal of Marine and Freshwater Research, 2005, Vol. 39:
373-382
0028-8330/05/3902-0373 © The Royal Society of New Zealand 2005
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