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2004 funds in spring 2005, but those results were incorporated into 2005 <br />Effort in other <br />years varied between 64 and 95 total samples. <br />Shorelines were the most common habitat type sampled, followed by ackwaters, <br />embayments, riffles, eddies, and isolated pools. Except for shoreline areas, de p runs and large <br />pools were only rarely sampled because discrete habitat areas and samples we e difficult to <br />obtain. The total number of samples and total samples per habitat type varied among years, but <br />was generally similar over the study period. <br />Yampa River fishes, species composition.-Composition of fishes in t e Yampa River <br />study area, 2003-2006, has changed since 1981-1982, based on comparisons of our samples to <br />nearshore, low-velocity habitat seine and dip net samples of Wick et al. (1985 collected in <br />1981-1982 (Table 3), and Anderson (2002) in our study area. Of six native fi hes historically <br />found, we captured only four, bluehead and flannelmouth sucker; roundtail ch b, and speckled <br />dace. We did not capture mottled sculpin, a species taken regularly by Ander on (2002) as <br />recently as 1999, even though we sampled several riffles that appeared to be s itable for <br />sculpins. We also did not capture mountain whitefish, although mainstem ele trofishing with <br />boats captured that species in 2005 and 2006 (Hawkins 2005; 2006). <br />Many more non-native fishes occur in the study area in the recent peri d compared to <br />1981-1982. Only seven non-native fishes occurred in samples collected in 1981-1982, compared <br />to 16 in the 2003-2006 period. Only red shiner, a rare species in 1981-1982, as not collected in <br />2003-2006. <br />Many of the species that have invaded the Yampa River and establish d since the 1981- <br />1982 period are potentially piscivorous including black bullhead, black crapp'e, bluegill, <br />northern pike, and smallmouth bass. Northern pike were likely in the study a ea in low numbers <br />as adults in 1981-1982 (Nesler 1995), but are now found as YOY in low velo ity habitats as <br />well. Species such as pumpkinseed, largemouth bass, and brown trout are ra a in the study area. <br />Species continue to invade the Yampa River study area. Iowa darter ppears to be the <br />most recent, being first detected in samples in 2003 in ]ow numbers, but incr asing since. Iowa <br />darter was apparently not present in 2001or before (Anderson 2002). Since i~ is distinctive, <br />9 <br />