7737 - Laserfiche WebLink

Home Browse Search

(Moore 1992). PIT Tag: Dorsal Musculature. Tag verification and survival were low for fish held in both the pond and raceway during the 511-day observation period. At day -195 five of the six pond fish had PIT tags; only 36% of raceway fish still had a PIT tag (Appendix; Table 8). At day 511 only 8 of 13 (62%) raceway fish retained their PIT tag. Survival of squawfish held in the raceway was greater than those held in the pond throughout the evaluation period (Appendix; Table 8)(Figure 3). On day 511,-only three squawfish (10%) had survived in the pond; 13 (43%) squawfish had survived in the raceway (Appendix; Table 8)(Figure 3). PIT Tag: Body Cavity. Tag verification was never less than 97% for fish either in the raceway or pond during the 51I-day period (Appendix; Table 8)(Figure 3) for fish of this size (mean FL=72 mm). For raceway fish at day 511, tag verification was significantly (P < 0.05) greater than fish PIT tagged in the dorsal musculature (X2=11.07, X2 o5, df=1, 5.02) or V. I. tagged (X2=43.00, XZ.os~ df=1, 5.02). These data are consistent with salmon smolts (65 mm) that have been successfully PIT tagged in the body cavity with minimal (0.5%) mortality and high (99%) tag retention (Prentice et al. 1987). Mortality was significantly (P < 0.05; X2=32.41, X2 o5, df=1, 5.02) greater for fish held in the pond than raceway throughout the study period (Appendix; Table 8) (Figure 3). V. I. T~ca At day 195, tag verification was 13% and 4% for fish held in the pond and raceway, respectively (Appendix; Table 8); at day-511 tag verification was 0% for each group (Figure 3). The Northwest Marine Technology, Inc. (NMT) representative who participated in implanting this tag cautioned us that tag retention may be low in such small fish. The minimum size for successful performance of this tagging system is about 150 mm (6 inches) based on studies (Haw et al. 1990) performed on Pacific salmon. The reason for this 14