New Zealand Journal of Marine and Freshwater Research abstracts
Population structure, individual movement, and growth rate of shortjaw
kokopu (Galaxias postvectis) in two North Island, New Zealand streams
Richard Allibone*
National Institute of Water and Atmospheric
Research Limited
P.O. Box 11 115
Hamilton, New Zealand
*Present address: Biodiversity Recovery Unit, Department of Conservation,
P.O. Box 10 420, Wellington, New Zealand. email: rallibone@doc.govt.nz
Dean Caskey
Department of Conservation
Stratford, New Zealand
email: dcaskey@doc.govt.nz
Rosemary Miller
Department of Conservation
Private Bag 3016
Wanganui, New Zealand
email: rmiller@doc.govt.nz
Abstract The shortjaw kokopu (Galaxias postvectis),
although widely distributed throughout New Zealand, is only known from a
few sites and generally with extremely low population numbers. Two sites
in Taranaki (Katikara Stream and Stony River tributary) were found to contain
relatively high densities of shortjaw kokopu. These sites were monitored
at 6-monthly intervals over 31/2 years to gather site
fidelity and growth rate data. Half-way through the sampling period the riparian
vegetation alongside the Katikara Stream site was destroyed. Although this
was unfortunate, it allowed examination of the impact of a disturbance event
of this nature on shortjaw kokopu growth and behaviour. The density of shortjaw
kokopu in Katikara Stream was about twice that in the Stony River tributary,
whose population was characterised by fewer but larger individuals. Growth
rate was significantly greater for smaller fish, and varied between the two
sites. Fish in the Katikara Stream were generally site loyal with only a
small percentage of mobile fish; however, greater movement from sites was
noted immediately after the disturbance event.
Keywords shortjaw kokopu; Galaxias postvectis;
galaxiid; growth; threatened; habitat; disturbance; movement; New Zealand
M02067 Received 28 August 2002; accepted 11 June 2003; Published 5 August
2003
New Zealand Journal of Marine and Freshwater Research, 2003, Vol. 37:
473-483
0028-8330/03/3703-0473 $7.00 © The Royal Society of New Zealand
2003
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