New Zealand Journal of Marine and Freshwater Research abstracts

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Swimming performances of some native freshwater fishes

C. P. MITCHELL

Ministry of Agriculture & Fisheries P.O. Box 6016 Rotorua, New Zealand

Abstract Observations were made of the response to water velocity for upstream migrating juveniles of 5 diadromous native fishes (Anguilla auslralis, Galaxiasmaculatus,Galaxiasfasciatus,Retropinna relropinna, Gobiomorphus colidianus). Swimming performance within a hydraulic flume was measured and observations made of the behavioural adaptions of some species to swim through high water velocities. Timed swimming at known water velocities allowed estimation of critical velocities for fish passage. For juvenile fishes (30-80 mm total length), velocities below 0.3 m s¹ should allow unrestricted passage over obstacles less than 15 m in length. Water velocities below 0.25 m s"¹ may be necessary for obstacles over 15 m. Field observations otMugil cephalus corresponded with limited flume data, suggesting this species is a less vigorous swimmer: water velocities below 0.15 m s"¹ would allow its passage over obstacles less than 5 m in length whereas longer obstacles, without resting areas of static water, may require velocities as low as 0.05 m s"¹ for M. cephalus.

Keywords native fresh water fish: fish passes; New Zealand; Pisces; Anguilla; Galaxias; Retropinna; Gobiomorphus

New Zealand Journal of Marine and Freshwater Research, 1989, Vol. 23: 181-187 0028-8330/2302-0181$2.50/0 © Crown copyright 1989 Received 22 May 1986; accepted 16 August 1988

PDF file of entire paper: medium quality (522K); (scanned from paper original: notes about this process)

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