8244 - Laserfiche WebLink

Home Browse Search

MANAGEMENT BRIEFS 853 TABLE 2.-Mean standard length (mm) and weight (g) of razorback suckers (N = 16) in each of the six treatment groups (Tl- T6) at the beginning and end of the experiment. Mean and standard error (SE) are calculated for the observed instantaneous annual growth rate in length, 5 September 1990 7 February 1992 Growth Rate Length Weight Length Weight Treatment (mm) (g) (mm) (g) Average SE T1 186.4 89.1 199A 98.9 0.049 0.012 T2 189.0 lOLl 197.9 105A 0.035 0.011 T3 192.5 II7A 204.2 122.3 0.043 0.007 T4 189.8 99.7 206.3 118.9 0.057 0.013 T5 203.5 114.9 213.7 119.2 0.Q35 0.007 T6 189.8 84.6 202.1 100A 0.041 0.013 will be acceptable for many fish species, the ef- ficacy of the sampling protocol must be demon- strated through controlled experiments that track acute and chronic effects, The performance of invasive tissue sampling can be evaluated against criteria proposed by Mor- izot et aL (1990): (1) extremely infrequent lethal- ity; (2) minimal effect on health and fitness; (3) ample yield of source material for analyses of pro- teins, DNA, trace chemicals, and perhaps cytology or histology; (4) minimal postsampling treatment and easy storage in laboratory or field conditions; (5) applicable to most fish taxa; and (6) minimal training required for technical personneL If these criteria are satisfied, it is reasonable to consider applying the protocol to large numbers of individ- uals, even of endangered species, with the expec- tation that few if any will experience significant harm, We assessed acute and chronic effects of inva- sive, but nonlethal tissue removal on three fish species from different families. Mortality was neg- ligible for rainbow trout and razorback suckers, and not attributable to tissue sampling procedures, 0.09 0.08 J: 0.07 l l! 0.06 l.'l j !!l 0.05 0 ! 0.04 J!I j 0.03 III .5 0.02 0.01 0.00 T1 T2 ! j T3 T4 T5 T6 Treabnents FIGURE 2,-Mean instantaneous annual growth rate (see Table 2) in length and 95% confidence interval for razorback suckers by treatment. High mortality of the bony tail chub was related to disease, and there was no indication that survi- vorship was decreased by the tissue sampling, As- sessment of chronic effects was limited to somatic growth rates, and there were no significant differ- ences in growth rates among the control and treat- ment groups for either rainbow trout or razorback suckers, Healing in all of the fish was rapid, and after a few weeks it was difficult to locate the sites where tissue had been removed, We conclude that this invasive sampling procedure had no signifi- cant effect on the health of either fish species, The dermal punches yielded approximately 15 mg of liver tissue or 50-60 mg of fin or muscle tissue, These amounts are ample for genetic char- acterizations (polymerase chain reaction; Simon et aL 1994), contaminant evaluations (selenium; Waddell and May 1995), and stable isotopic anal- ysis (Fry et aL 1996), The materials required (der- mal biopsy punch, scalpel, sutures) are readily available from suppliers of surgical equipment. With practice, the surgical procedures can be per- formed very quickly, The liver biopsy was the most complicated procedure, but the complete sur- gical procedure took only an average of 2,7 min (9 trials), Incision and suturing (no tissue removal) required an average of 2.3 min (9 trials), so most of the time required for the liver biopsy is related to the opening and closing of the incision, Dermal punches of fin and muscle tissue were obtained in much less time. Because we did each individual fish in turn, not in batch, the effects of the anes- thetic were greatly diminished, as indicated by maintenance of equilibrium and initiation of swim- ming in less than 5 min after treatment. We con- cluded that the developed protocol satisfies above- mentioned criteria proposed by Morizot et aL (1990), The results of this study were sufficiently en- couraging that USFWS issued permits to allow at