New Zealand Journal of Marine and Freshwater Research abstracts

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Cover preference tests of juvenile shortfinned eels (Anguilla australis) and longfinned eels (A. dieffenbachii) in replicate channels

G. J. GLOVA

National Institute of Water & Atmospheric
 Research Ltd
P. O. Box 8602
Christchurch, New Zealand

Abstract  The day-time cover preferences of three size groups (small = <100; medium = 100-199; large = 200-299 mm total length (TL)) of juvenile shortfinned eels (Anguilla australis) and longfinned eels (A. dieffenbachii) were tested during summer in replicate channels provided with natural (macrophytes, woody debris, cobbles) and artificial (shade, plastic pipes) cover types. Tests on the longitudinal distribution of all three size groups of shortfinned eel (with no cover in the channels) revealed no significant bias in the distribution of small and medium eels, but did so for large eels which favoured the ends of the channels. Similar bias occurred in the actual cover preference tests, which was adjusted for by the Poisson log-linear model used in analysing the data. When the species were tested separately, small and medium eels of both species preferred cobbles and macrophytes more or less equally, whereas large eels showed a clear preference for macrophytes and a minor attraction for cobbles. When tested together, species cover preferences differed significantly, with a greater proportion of all sizes of longfins in the cobbles and shortfins in the macrophytes and woody debris. Artificial cover was an unattractive alternative to natural cover for all sizes of both species of eel. The results of these experiments suggest that both size and species interactions influence the distribution of juveniles of both species in the wild.

Keywords  juvenile eels; shortfinned; longfinned; cover preferences; replicate channels

M98071
Received 30 September 1998; accepted 30 December 1998

PDF file of entire paper: medium quality (1263K); (scanned from paper original: notes about this process)

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