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<br />Testing <br /> <br />Swimming Performance Tests <br />A velocity chamber was used to measure swimming stamina. The chamber consisted of a DC- <br />powered motor with a calibrated rheostat, enclosed propeller, and a flow chamber that was constructed <br />of a small diameter IS-cm Plexiglas tube mounted inside a larger one. Water was circulated through the <br />smaller tube and returned to the propeller from the interspace between the tubes. A terminal port <br />allowed access to place and retrieve test fish. Fresh water was circulated through the apparatus to <br />provide adequate dissolved oxygen (fig. 3). <br /> <br /> <br />Figure 3. Flow chamber used to measure swimming stamina. <br /> <br />Fish were subjected to velocity increments based on their body length (body length units/second <br />[BUs D. The test started with an acclimation period of 30 minutes at a flow rate of 0.5 BUs. For <br />example, a 20-cm- TL fish would be acclimated to a 10 cm/s velocity for 30 minutes. Following <br />acclimation, velocities increased by 0.5 BUs increments for 30-minute periods until the fish collapsed <br />from exhaustion. At that point the experiment ended and critical swimming performance was calculated <br />using the formula: <br />Ucrll = Vp + ((t/t)V)), where, <br />Vj is the velocity increment (cm/s). <br />Vp is the penultimate velocity where the fish swam in the entire interval (cm/s). <br />tl is the elapsed time from the velocity increase to fatigue. <br />ti is the time interval. <br />The goal was to test 30 fish of similar size from both exercise and control groups. <br /> <br />5 <br />