9703 - Laserfiche WebLink

Home Browse Search

Notably, the three control fish in the 21-cm-size class and the two control fish in the 25-CIll-Wl' classes had higher Veri' (cmlS) than their exercised counterparts (fig. 7), which appeared tn be the opposite trend compared to the other size classes (20-, 22-, 23-, and 24-cm TL). Therefore we examined the density distribution of Veri' (BUs) to see if these values may have altered the overall trend of U,,,, (BUs). The five Veri' (BUs) values were not out of the ordinary compared to the rest of the distribution. Observed Veri' (BUs) for 21-cm control fish were 3.35, 2.75, 2.67; and 2.45 and 2.48 for the 25-cm control fish. The single 25-cm treatment fish had a Verit (BUs) value of 1.52. Although the size classes were slightly imbalanced, there were no significant differences in lengths between exercised and unexercised fish used in the flow chamber experiments (table 2: [WO- sample t-tests: p = 0.5). Therefore we used all 60 fish to examine the distributions of critical now velocity (V) between treatments. The V . data were skewed to the left. especiall)' for excrciscJ i"ish cnl enl (fig. 7; table 2). Therefore we ran nonparametric tests to compare distributions between treatlllellls. The average deviations in cumulative distributions of Ueril (BUs) for exercised fish were not significantly different from unexercised fish (one-tailed MRPP two-group comparison; standardized test statistic = -0.15; p = 0.15). However, the maximal differences in cumulative distribution of U,,, (BUs) indicate exercised fish deviated significantly from control fish (fig. 7; one-tailed Kolmogorov-SlTIIrnov tW()- sample test, D = 0.33; p = 0.035). Based on the latter statistical test and the distribution patterns. 50 percent more exercised fish than control fish (21 vs. 14) attained critical tlow velocities of 2.5 body lengths/s or higher (fig. 8). Bonytail Similar tests were conducted for bony tail without the screen modification. Even though we did not have an exercise group, we tested 30 control fish to develop base-line data for the species. Approximately 10 percent of the bony tail also exhibited the "drafting" behavior that was previously described. Trials were ended at the 4.5-BUs level for convenience of time. Our primary concern was to test whether poor stamina contributed to the death of the exercised bony tail. Ten (33 percent) of our trial fish exceeded the 4.5-BUs level of endurance, far surpassing the average endurance shown by razorback suckers (3.36 versus 2.24 (BUs) (table 3). Average, median, and maximum swimming performances reported in table 3 are conservative values (Appendix B) since some fish exceeded our 4.:1 BUs test limit. Table 2. Frequencies of razorback sucker by size class and treatment in flow chamber tests. Control Exercised Total Razorback sucker size class (mm- TLI Totals 200 210 220 230 240 250 4 3 8 7 5 , 2LJ - 4 7 8 5 () . , , I 8 10 16 12 II . hll . ~-~-_.__.- ----- Treatment 12