New Zealand Journal of Marine and Freshwater Research abstracts
Spawning site selection by two galaxiid fishes, Galaxias anomalus and
G. depressiceps, in tributaries of the Taieri River, South Island, New
Zealand
SUZANNE J. MOORE1
Department of Zoology
University of Otago
P. O. Box 56
Dunedin, New Zealand
RICHARD M. ALLIBONE2+
Otago Conservancy
Department of Conservation
P. O. Box 5244
Dunedin, New Zealand
COLIN R. TOWNSEND
Department of Zoology
University of Otago
P. O. Box 56
Dunedin, New Zealand
1Present address: Waikato Conservancy, Department of Conservation,
P. O. Box 3072, Hamilton, New Zealand.
2Present address: National Institute of Water & Atmospheric
Research Ltd, P. O. Box 11 115, Hamilton, New Zealand. email:
r.allibone@niwa.cri.nz
Abstract Recent studies have led to the recognition of
Galaxias depressiceps and reinstatement of Galaxias anomalus. The
two species maintain near allopatric distributions and it has been suggested
that spawning habitat availability, at least partially, controls the
distribution of these species. The spawning habitat of each species was
determined and an assessment of the influence of spawning habitat availability
on the distribution of the two species was carried out. Factors that may have
influenced the onset of spawning were also examined. We found that G.
depressiceps selected spawning sites with a high proportion of boulder
substrata and nests were found on the underside of or between boulders. G.
anomalus spawned within the streambed substrata, under boulders or cobbles,
in shallow water and narrow channels relative to the available habitat.
Suitable boulder spawning substratum for G. depressiceps in the G.
anomalus sites was limited and this supports the hypothesis that
spawning habitat availability influences G. depressiceps distribution.
Conversely G. anomalus spawning habitat was available in G.
depressiceps streams, indicating that spawning habitat limitations are not
restricting G. anomalus. The onset of spawning, for both species, did
not appear to be related to daylight, phase of the moon, or stream water level,
but all species started spawning as water temperatures rose. The proximity of
G. anomalus spawning sites to the stream edge and their occurrence in
poorly consolidated substrata presents two management issues. Water abstraction
may expose spawning sites if stream water levels are lowered, and these sites
are vulnerable to trampling by stock.
Keywords spawning; galaxiid; Galaxias anomalus;
Galaxias depressiceps; Taieri River; habitat
+Author for correspondence.
M97063
Received 17
October 1997; accepted 31 August 1998
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