Abstract The spatial organisation and behavioural interactions between giant kokopu (Galaxias argenteus) of varying sizes were investigated in two stream pools which varied in fish density. The spatial distributions of fish in Pool A were more exclusive, exhibited less overlap, and appeared to be more stable than those for fish in Pool B. The distinct difference observed between the two pools may have been influenced by fish density which was lower in Pool A (0.27 fish/m2) than in Pool B (0.51 fish/m2). A linear, size (weight) related dominance hierarchy appeared to exist within both pools whereby the heaviest individual was the most dominant. Though primarily nocturnal in habit, the social structure and behaviour of giant kokopu (when active during the day) was comparable to that exhibited by other drift-feeding fish in the Northern Hemisphere.
Keywords spatial distribution; dominance hierarchy; giant kokopu; behavioural interactions; fish density
M02034 Received 23 May 2002; accepted 31 October 2002; Published 20 June
2003
New Zealand Journal of Marine and Freshwater Research, 2003, Vol. 37:
315-322
0028-8330/03/3702-0315 $7.00 © The Royal Society of New Zealand
2003
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