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<br />, . <br /> <br />..~ ~ <br /> <br />1. <br /> <br />. <br /> <br />ATIACHMENTS <br /> <br />The following information was extracted from reports prepared for the 1998 Standardized <br />Monitoring Program (ISMP). <br /> <br />Adult monitorinl!: throullh Deriodic mark-recaDture DODulation estimates <br /> <br />. <br /> <br />Bacwound <br />In 1997, a report was completed by Osmundson and Burnham outlining the current status and <br />trend of the Colorado squawfish population in the Colorado River mainsWm- They used a four- <br />year mark-recapture effort to estimate the size of the subadult and adult population. In the report, <br />the author's concluded that the current reason for the low numbers of adult Colorado squawfish in <br />the Colorado River was a low frequency of strong year classes. Strong year classes in 1985 and <br />1986 recruited to the adult population during theirl991-1994 study, allowing the authors to <br />document the large effect that a couple of strong year classes can have on adult population size. In <br />the first year of the study (1991) most adults were found concentrated in the upper reach of the <br />river (upstream of Westwater Canyon) and this population consisted of only about 200 individuals. <br />By 1994, catch rates there had doubled. The 1994 point estimate for the upper reach was about <br />330 fish; though not double, it was substantially higher than that estimated three years prior. In <br />addition, an additional 300 or so young or soon-to-be adult fish were estimated to reside in the <br />lower reach (downstream of Westwater Canyon). Thus, in four years the river-wide adult <br />population increased from somewhere around 200-250 fish to around 600 fish. <br /> <br />In a second report, Osmundson et al. (1997) documented the dispersal of these young, recruiting <br />adults in the lower reach and showed that many of these young fish were moved to the upper <br />reach. Based on body condition in the lower reach that declined as the fish grew and later <br />improved upon arrival in the upper reach, along with differences in forage between the two <br />reaches, the authors concluded that these upstream movements Were related to an inadequate <br />supply offood for adult squawfish in the lower reach. <br /> <br />New information from 1998 <br />In 1998, a second mark-recapture study was begun to monitor the status of this dynamic <br />population - this time a three-year effort is planned instead of a four-year effort. In 1998, the same <br />protacol was used as before: three passes, or capture efforts, were made through the upper reach <br />and two passes through the lower reach. With each pass, trammel-netting of backwaters, and <br />flooded canyon mouths was used to capture fish during the nm-off period. In the upper reach, <br />captures were as follows: first pass, 32 fish; second pass, 67 fish; third pass, 43 fish. In the lower <br />reach: first pass, 3 I fish; second pass, 65 fish. <br /> <br />Results of the first year of data collection have proved interesting. To begin with, there has been <br />additional recruitment of sub adults from year-cJasses following the 1985-1987 year-classes that <br />. were previously descnDed, i.e., in the lower reach, a fair number offish in the 35~50 mrn size <br />