New Zealand Journal of Marine and Freshwater Research abstracts
Use of in-stream cover types by adult banded kokopu (Galaxias fasciatus)
in first-order North Island, New Zealand, streams
David K. Rowe
Joshua Smith
National Institute of Water and Atmospheric
Research Limited
P.O. Box 11 115
Hamilton, New Zealand
email: d.rowe@niwa.co.nz
Abstract The relative importance of wood material in
providing in-stream cover for adult banded kokopu (Galaxias fasciatus)
was determined in first-order, North Island, New Zealand, streams. Three
groups of streams, each differing in the relative amount of three types of
in-stream cover (i.e., wood, boulders, undercut banks) were selected and
banded kokopu were sampled in their pools using electric fishing. Banded
kokopu occurred beneath boulders, undercut banks, and wood material in all
pools except those lacking any in-stream cover, or those where large (total
length >400 mm) eels were present. Their presence in pools was therefore
highly dependent on in-stream cover, provided large eels were absent. In
streams where the cover provided by boulders was lacking, banded kokopu selected
mainly undercut banks and wood. However, in streams containing large amounts
of bank and boulder cover, wood was under-utilised, indicating that it was
least preferred. In pools providing a choice of cover types, bank cover was
more frequently used than other types, indicating that it is preferred. The
mean size of banded kokopu in pools was positively related to their relative
abundance, and their abundance was in turn related to habitat quality as
defined by in-stream cover. Streams with the least amount of bank cover had
the lowest number of pools occupied by banded kokopu, fewer banded kokopu
per pool, fewer pools containing two or more banded kokopu, and the smallest
banded kokopu. Collectively, these data indicate that bank cover in pools
provides optimal habitat for banded kokopu, and that wood material was important
only where other types of more permanent cover were lacking. Logs and wood
slash from logging operations could therefore be important for increasing
banded kokopu habitat in logged streams where bank and boulder cover are
scarce.
Keywords wood material; bank cover; substrate; in-stream
cover; habitat
M02104 Received 23 December 2002; accepted 5 May 2003; Published 5 August
2003
New Zealand Journal of Marine and Freshwater Research, 2003, Vol. 37:
541-552
0028-8330/03/3703-0541 $7.00 © The Royal Society of New Zealand
2003
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