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852 TYUS ET AL. TABLE I.-Mean standard length (rnm) and weight (g) of rainbow trout (N = 12) in each of the six treatment groups (Tl-T6) at the beginning and end of the experiment Distributions of initial and final lengths were sampled repeatedly in a Monte Carlo simulation to obtain the mean and standard error (SE) of the instantaneous annual growth rate distribution for each treatment 6 July 1990 7 December 1990 Growth rate Length Weight Length Weight t Treatment (mm) (g) (mm) (g) Average SE Tl 245.4 230.3 364.3 1,042,5 0.94 0.05 T2 246.2 233.3 355.9 945.3 0.87 0.07 T3 250.8 243.2 363.4 1,021.3 0.88 0.07 T4 240.3 219.3 361.0 1,019.2 0.97 0.07 T5 254.4 273.7 371.4 1,155.0 0.90 0.06 T6 259.6 278.8 374.3 1,189.1 0.87 0.08 ing, All but two fish in the surgical groups had their incisions completely covered by new tissue, areas from which muscle plugs had been removed were filling, and holes through the pelvic fins had closed over, At study termination, it was difficult, in most fish, to locate the surgical lesions or sites where muscle or fin plugs had been removed, At that time, growth was substantial in all treatment groups: mean length increased by over 100 mm, and weight increased by at least four fold (Table 1), The Monte Carlo simulation provided growth rate means and standard deviations for each treat- ment, and standard errors were computed for each mean using sample size of 12 (except for T6 where N = 11), The means of all treatments fell within the 95% confidence interval of the mean growth rate for the control group (Figure 1), demonstrat- ing that growth rates were not altered significantly by anesthesia, surgery, or tissue removaL Thus, the rainbow trout showed no chronic effects from the tissue removal protocoL Ninety-six razorback suckers (initial means :!:: SD: length = 191.5 mm :!:: 44,7 and weight = 98,8 1.2 1.0 t t t t t f ~ i e 0.8 CI .. " g 0.6 c S j 0.4 .. .5 0.2 0.0 T1 T2 T3 T4 TS T6 Treatments FIGURE I.-Mean instantaneous annual growth rate (see Table 1) in length and 95% confidence interval for rainbow trout by treatment g :!:: 116.4) were studied for 17 months, At study termination there was a great difference in growth of different individuals, but overall growth was slight (Table 2), No difference was detected in growth rate (G) of individuals among any of the treatments (Kruskal-Wallis test, P = 0.3945; Fig- ure 2), Twelve of 17 razorback suckers preserved for further study had been subjected to surgical incisions (from four treatments), and dissection re- vealed no obvious adverse manifestations (e,g" ad- hesions) of surgery, Results of tissue removal in razorback suckers were similar to those obtained with rainbow trout, and we concluded that the tis- sue removal protocol had no discernible chronic effects, Seventy eight bony tail chub (initial means :!:: SD: length = 228.3 mm:!:: 30.7 and weight = 96,6 g :!:: 41.1) were studied for 18 months, At the close of the study only 22 fish survived the ich outbreak, and these fish displayed only slight growth (means :!:: SD: length = 2335 :!:: 28,70 and weight = 98.36 :!:: 39,66; N = 22). This small number precluded significance testing for differences between treat- ment growth rates, but there was no difference between survival of fish in the treatment groups when compared with the controL Four of the seven bony tail chub preserved for further study had been subjected to surgical incision and, as with razor- back suckers, showed no adverse internal effects of surgery, Discussion Technological advances have made it possible to examine biochemical composition of fishes by use of small tissue samples (e.g" Simon et aL 1994; Waddell and May 1995; Fry et aL 1996), Invasive tissue sampling procedures can provide adequate amounts of tissues for use with a vast array of techniques, but before invasive techniques