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-16- <br />Johnson 1970, Dicconnell and Gerdes 1964). Sampling for several consecutive <br />years at established reservoir locations in Lake Powell should better define <br />fluctuation patterns in shad populations. <br />Lake Powell shad were found to grow throughout the summer. Young-of- <br />4h <br />commnly reached 30-45 mm by early September (Figure 2). Kersch <br />(1970) stated that shad grew approximately one inch per month for the first <br />three months. However, Johnson (1970) documented a short shad growing season <br />limited to early summer in central Arizona lakes. He thought factors such <br />as food supply and intraspecific competition also influenced growth rate. <br />Lake Powell shad attained a maxim= length of 176 rim as adults. Others have <br />reported maximm lengths of 136 mm in Lake Havasu (Kimsey et al. 1967), 172 <br />mm in Pena Blanca (McConnell and Gerdes 1964), 164 mm in Lake Pleasant (Haskell <br />1959), and 172 mm in Roosevelt Lake (Beers and McConnell 1966). <br />R,eccalmendaticros <br />Consistent trawl sampling should be continued to d=Vent trends in <br />shad population dynamics. Work should be continued during the next project <br />segment at established sampling sites near Wahweap, Bullfrog, and Hite. Sev- <br />eral years data would be valuable in establishing what degree of fluctuations <br />might be expected in shad year class strength before increasing striped <br />bass numbers become an influencing factor. <br />The standard trawling tow should be investigated to better determine <br />fishing depths being utilized. Vertical distribution of shad as determined <br />by sonar and trawl samples can be related with temperature profiles to de- <br />fine a preferred range of habitation. Maximtma trawl depth needed to produce <br />most consistent catches during all seasons and weather conditions should be <br />determined and employed.