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1 <br />1 <br />1 <br />I <br />1 <br />t <br /> <br />sulfide toxicity was a possible cause of death, it was concluded that the high incidence of <br />tapeworms in the digestive tracts contributed to the mortality of the squawfish. <br />In 1989, all ponds were checked at ice-out for winterkill and no dead fish were <br />found. Gardner Pond was sampled prior to and following ice-out in 1988-89 and found <br />to contain other fish species that included common carp (Qarinmus ca io), green sunfish <br />Le omis cyanellus), black bullhead Ictalurus melas), and fathead minnow (Pimephales <br />promelas). Though dissolved oxygen was low in Gardner Pond in February, the <br />overwinter survival of these fish appeared to be high. The fate of roundtail chub in <br />Gardner and 13th-hole pond is unknown, but their low survival may have been attributed <br />to their inability to adjust to these particular pond habitats. <br />Laboratory Studies <br /> <br />Colorado squawfish <br />Hotchkiss NFH. The control (38 fish) and one experimental group (37 fish) were <br />1 <br />1 <br />i <br /> <br />1 <br />n <br />established 27 July 1989 (Table 1). Hatchery personnel indicated that six fish (3 control <br />and 3 PIT tagged) were unknowingly lost through a water outlet valve during routine <br />cleaning and flushing of water from the tank following tagging. These six dead fish were <br />later recovered. On day 70 the fish were again checked. Of the 34 PIT-tagged fish <br />remaining, tag retention and verification was 100%, and wound healing was almost <br />complete. Eighty-five percent of the tagged fish observed had only a small scar <br />noticeable by careful examination. This portion of the study demonstrated that Colorado <br />squawfish as small as 120-165 mm (11-28 g) could be successfully PIT tagged. The study <br />22 <br />