Bioenergetics and swimming efficiency of juvenile scalloped hammerhead sharks, Sphyrna lewini, in Kaneohe Bay, Oahu, Hawaii
Bioenergetics and swimming efficiency of juvenile scalloped hammerhead sharks, Sphyrna lewini, in Kaneohe Bay, Oahu, Hawaii
Date
1998-08
Authors
Lowe, Christopher G.
Journal Title
Journal ISSN
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Publisher
University of Hawaii at Manoa
Abstract
The goal of this study was to determine the energetic
requirements of juvenile scalloped hammerhead sharks (Sphyrna
lewini) in Kaneohe Bay, Oahu, Hawaii using a multidisciplinary
approach. A large flume/respirometer (635 1)
was constructed to determine the critical swimming speeds
(Ucrit )' swimming kinematics (tailbeat frequency, tailbeat
amplitude, and stride length), and oxygen consumption rates
(V02 ) of juvenile sharks over a range of swimming speeds (U).
Swimming kinematics were also compared with unconstrained
sharks in a seawater pond. These experiments indicated that
tailbeat frequency (TBF) and water temperature could be used
as a predictor of U and V02 for free-swimming sharks in the
field; however, the flume affected the sharks' swimming
kinematics at slow speeds. The flume and pond kinematic
comparisons were used to correct for flume effects on sharks'
V02.
An acoustic tailbeat-sensing transmitter was designed
and constructed to quantify activity and energy consumption
of free-swimming hammerhead shark pups in Kaneohe Bay.
Sharks with transmitters behaved similarly to uninstrumented
sharks, but incurred a 28% increase in cost of transport due
to increased drag from the transmitters. These data were
used to correct for the effects of the transmitter on freeswimming
sharks in the field. Sharks tracked in Kaneohe Bay with tailbeat transmitters
exhibited increased U during dawn and dusk, while sharks
tracked in the warmer summer months had higher activity rates
and metabolic rates (MR) than a shark tracked during the
winter. Sharks tracked in this study had higher MR than
those measured for other species of tropical sharks and, as a
result, require higher daily rations. Low and negative
growth rates determined from sharks in the Bay and declining
catch rates over the season suggest that a large percentage
of the pups in Kaneohe Bay may starve as the result of their
high metabolic requirements. Although prey do not appear to
be li~itingi lack of foraging experience compounded by a high
daily metabolic demand may explain why sharks lose weight
during summer months. Those pups that survive the winter
experience lower MR due to seasonal temperature decline and
less competition as the result of high neonatal mortality.
Description
x, 130 leaves, bound : ill. (some col.) ; 29 cm.
Missing page 74.
Missing page 74.
Keywords
Citation
Lowe, Christopher G. Bioenergetics and swimming efficiency of juvenile scalloped hammerhead sharks, Sphyrna lewini, in Kaneohe Bay, Oahu, Hawaii. Honolulu (HI): University of Hawaii at Manoa, 1998.
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