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whether the other tagged fish had left the area, died or somehow evaded capture. It is possible that fish do not establish permanent residence in the area, and continue moving downstream after a short time. This downstream movement could account for the difference in catch rate observed in the two studies. However, one tagged pike remained in the area for 2 years and the other remained there for 3 years before they were removed from the river. Mother possible explanation could be removal of northern pike by anglers. Before beginning this study, local anglers were notified that northern pike were going to be removed from the river. Much of the limited angling that occurred prior to the notification had been catch and release. However, after hearing about this project, some anglers indicated that they would remove northern pike themselves rather than return them to the river as they had done in the past (B. Burdick, USFWS, personal communication}. It is possible that they caught and removed some pike before the study began. However, it is impossible to determine how many northern pike may have been caught and kept by local anglers. It is also possible that the lack of recaptures and the immediate decrease in electrofishing success was because pike that were not captured learned to avoid the electrofishing boat. However, no pike were observed when electrofishing that could not be captured, and the lack of northern pike in off-channel habitats suggests that the decline in pike numbers was real. Based on high use of sloughs and other flooded-vegetation habitats in the Yampa River, it seems unlikely that pike would have remained in the main channel, away from quiet-water habitats during runoff. The low catch rate in 1996 also suggested that pike did not rapidly recolonize the study area from upstream. However, it is difficult to draw conclusions about reinfiltration rates based on 1 year of data. The source of new pike is small ro removal efforts should remain effective for several years at a time. However, removal will have to be a regular activity until northern pike have been eliminated from Paonia Reservoir. Nesler (1995) removed northern pike from parts of the Yampa River from 1989-1992. His study area was similar to the Gunnison River in that reproduction occurred upstream and recruitment to the population came from the upstream reach. However, the Yampa population was considerably larger than found in the Gunnison River and reproduction 13