New Zealand Journal of Marine and Freshwater Research abstracts
Avoidance of suspended sediment by the juvenile migratory stage of six New
Zealand native fish species
JACQUES A. T. BOUBÉE
TRACIE L. DEAN
DAVID W. WEST
RHYS F. G. BARRIER*
National Institute of Water & Atmospheric
Research Ltd
P. O. Box 11-115
Hamilton, New Zealand
*Present address: Department of Conservation, P. O. Box 5, Nelson, New
Zealand
Abstract The avoidance response of the migratory juvenile
stage of six species of diadromous fish to different levels of suspended solid
(SS) was determined in the laboratory using a two-choice avoidance tank. Trials
were mostly conducted with resuspended sediment from the outlet of Lake Waahi,
New Zealand, but a series of tests was also conducted with kaolin for
comparison. Banded kokopu (Galaxias fasciatus) was the most sensitive
species, displaying a 50% avoidance response to kaolin and Waahi silt at 17 and
25 NTU, respectively. Koaro (Galaxias brevipinnis) and inanga
(Galaxias maculatus) were found to be less sensitive than banded kokopu,
with a 50% avoidance response to Waahi silt at 70 and 420 NTU, respectively.
Shortfinned and longfinned elvers (Anguilla australis and A.
dieffenbachii), and redfinned bullies (Gobiomorphus huttoni) showed
no avoidance behaviour, even at the highest turbidities (1100 NTU) tested.
Based on these laboratory results, and until field testing is undertaken, a
limit of about 15 NTU in otherwise clear waterways should ensure that the
upstream migration of some of the most common New Zealand native freshwater
species will not be affected.
Keywords suspended solids; turbidity; fish; migration;
avoidance; galaxiids; elvers; Anguilla australis; A. dieffenbachii; Galaxias
fasciatus; G. maculatus; G. brevipinnis; Gobiomorphus huttoni
New Zealand Journal of Marine and Freshwater Research, 1997: Vol. 31:
61-69
0028-8330/97/3101-0061 $2.50/0 (c) The Royal Society of New Zealand
PDF file of entire paper: medium quality (689K); (scanned from paper original: notes about this process)
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