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18 <br />Temperature and temperature preference <br />Backwater temperature has been shown to be correlated to squawfish use of habitat (Tyus 1991). <br />ISMP sampling guidelines call for sample sites to be 2° warmer than the main channel temperature <br />(ISMP 1989). However no correlation of squawfish habitat use to temperature has been found during <br />this study. <br />Main channel temperatures were consistently within the lower three degrees of the range of <br />available temperatures in backwaters or main channel, and in all years the mean maximum backwater <br />temperatures were at least 2° higher than the main channel, and most of the available nursery habitat <br />was warmer than the main channel. In low or medium water years, the MS habitats tended to be <br />warmer than the SC habitats (Table 8). Since squawfish prefer~SC habitats, but these habitats tended <br />to be cooler than other habitats, the temperature preference by squawfish is confounded. There was <br />r <br />some evidence that squawfish prefer the warmer areas within the larger habitats, found near the <br />shallow end of the backwater, but these results were not consistent. In high water years, SC habitats <br />were slightly warmer than MS habitats. <br />Some additional temperature data from habitats were obtained by placing remote sensing <br />thermographs in each section. They were each placed to record mid-column temperature fluctuations <br />in backwaters. Due to several incidences of instrument loss and malfunction, the data are not <br />continuous and will not be reported here. However, in the Green River, the main channel <br />thermograph data was found to be highly correlated with the USGS temperature data. Therefore, the <br />USGS information was used to represent the main channel. In the backwaters, daily fluctuations were <br />usually 2-5° . Although the fluctuations could have been much higher in the shallow ends of the <br />backwaters, we did not have instruments placed there. Although maximum habitat temperatures <br />were higher than the main channel, results from the Green River thermographs show that temperature <br />