New Zealand Journal of Marine and Freshwater Research abstracts

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Effects of the presence of subadult longfinned eels (Anguilla dieffenbachii) on cover preferences of juvenile eels (Anguilla spp.) in replicate channels

G. J. GLOVA

National Institute of Water & Atmospheric
 Research Ltd
P. O. Box 8602
Christchurch, New Zealand
email: g.glova@niwa.cri.nz

Abstract  The effects of the presence of subadult (420-875 mm total length (TL)) longfinned eels (Anguilla dieffenbachii Gray) on day-time cover preferences of three juvenile size groups (small = <100; medium = 100-199; large = 200-299 mm TL) of shortfinned eels (A. australis Richardson) and longfinned eels were tested in replicate channels provided with natural (macrophytes, cobbles, woody debris) and artificial (shade, plastic pipes) cover. Macrophytes, cobbles, and woody debris were the most frequently occupied cover by both species of juvenile eel, whereas overhead shade and plastic pipes were rarely used. In most instances, the subadult longfinned eels occupied the macrophytes, the cover type preferred by juvenile eels when tested in the absence of subadult eels. The small juvenile eels used the three natural cover types similarly between species, whereas the cover preferences of medium and large juvenile eels differed between species--whether tested in species unmixed or mixed situations, shortfinned eels preferred macrophytes and longfinned eels preferred cobbles. It is concluded that as juvenile eels increase in size in the wild, their cover preferences will be more restricted because of greater interaction with that of predatory subadult eels in the population.

Keywords  cover preferences; juvenile eels; Anguilla spp.; presence of subadult longfinned eels; replicate channels

M00022

Received 9 May 2000; accepted 12 October 2000

New Zealand Journal of Marine and Freshwater Research, 2001, Vol. 35: 221-233

0028-8330/01/3502-0221 $7.00 (c) The Royal Society of New Zealand 2001

PDF file of entire paper: medium quality (964K); (scanned from paper original: notes about this process)

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