A tool for determining maximum sustained swimming ability of selected inland fish species in an Afrotropic ecozone
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Date
2018Author
Botha, T.L.
Mahloko, M.P.
Wepener, V.
Howatson, G.
Smit, N.J.
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Critical swimming speed (Ucrit) predicts the maximum sustained swimming velocity that various fish species are able to
sustain for prolonged periods. The objective of this study was to determine the Ucrit of Afrotropic ecozone fish, determine
oxygen consumption at Ucrit and relate the resulting optimum flow requirements to effective movement through fishways
under South African flow conditions. The selected fish species were Coptodon rendalli, Tilapia sparrmanii, Pseudocrenilabrus
philander, Oreochromis mossambicus and Enteromius trimaculatus. Ucrit and oxygen consumption (MO2) were measured in a
swim respirometer at 5-min intervals, at increasing velocity increments of 0.5 cm·s−1 until volitional exhaustion. No significant
differences were seen in the Ucrit values between C. rendalli, T. sparrmanii and P. philander, but all species significantly differed
from O. mossambicus and E. trimaculatus, which had the highest Ucrit (17.6 ± 1.5 bl·s−1 and 18.2 ± 2.8 bl·s−1). Size plays an
important role in the swimming performance of fish, with larger fish able to sustain a greater velocity, which was specifically
true for O. mossambicus in this study. Additionally, smaller fish consumed more oxygen during swimming and therefore used
more energy, experiencing relative physiological strain. Based on these data, flow respirometry was shown to be a useful tool
to determining prolonged swimming abilities of South African fish species, and can help inform the structure and flow rates
of culverts and fishways
URI
http://hdl.handle.net/10394/30870http://dx.doi.org/10.4314/wsa.v44i3.19
https://www.ajol.info/index.php/wsa/article/view/175505