Training, Speed and Stamina in Trout

Abstract

1. A number of trout (Salmo irideus) were kept continuously swimming for a period of 12 months in experimental tanks in which the water was made to rotate at a mean speed of 25 cm./sec. 2. These fish become available for study in the ‘Fish Wheel’ and measurements were made of the maximum speed they sustained for periods of swimming of different duration. 3. For bursts of swimming of up to 20 sec. duration the mean accomplishments of these fish were identical with those of the unexercised trout studied previously. 4. Considerable variability was found amongst the specimens tested and the best of the present exercised fish were appreciably better than the best of the previous unexercised ones. The biggest improvement was 36 % at the 10 sec. period of swimming; the mean percentage improvement for all periods was 11 %. 5. Some specimens were found better at swimming for short periods and others at swimming for longer. 6. In the absence of comparable figures for the earlier fish, the measurements of cruising speeds sustained for periods up to 1½ hr. were compared with other figures in the literature and found to be about half some of these for wild fish. 7. The implications of the results are considered and two interpretations stressed. First, it is assumed that there is a real identity of accomplishment for short periods of swimming, values being determined perhaps solely by gross mass of muscle; while for longer periods of swimming differences dependent upon respiratory rate etc. may well occur. Secondly, for such longer periods the discrepancies reported here may well be accounted for by differing degrees of stimulus and behavioural response under varied experimental conditions.