Laserfiche WebLink
<br />DISCUSSION <br />It is important to note that this study was designed to evaluate larval razorback sucker <br />and bonytail survival in a natural floodplain depression. Natural in this case includes nonnative <br />fish predators and competitors. <br />The essence of the reset theory is the timing of larvae entering the floodplain. Age-0 <br />nonnative species did not appear for almost two weeks following endangered larval fish <br />i <br /> <br />introduction. It appears that endangered larval fish can withstand the predation from the ~ <br />relatively few adult non-native fish that enter the floodplain at connection. Past experience has <br />suggested that they cannot withstand the predation present when they enter floodplains that <br />contain large numbers and multiple cohorts ofnon-native fish that over-wintered (Birchen and ~ <br />Christopherson 2004). <br />Zooplankton peaks occurred shortly after the floodplain filled allowing for optimum food <br />availability with minimal inter-species competition. Thus, when the greatest concentration of ~ <br />zooplankton was available, little inter-species competition existed and growth rates <br />approximated 1 mm/d. With the fast growth start, larval endangered fish were able to maintain a <br />size advantage over many nonnative fish young-of--year spawned in the site. ~ <br />Size was also likely a major factor in avoiding predation. The larval endangered fish <br />were able to grow fast enough to avoid predation by the numerous age-0 non-native predators. <br />Conversely, in the study by Birchen and Christopherson (2004), multiple age classes of non- ~ <br />native predators, which included juvenile black bullhead and green sunfish, likely predated <br />heavily on endangered larval fishes. <br />The timing of the larval introduction was similar to their natural appearance in <br />floodplains. Razorback sucker spawn on the ascending limb of the hydrograph and are among <br />the first fish in this system to spawn each spring. Larvae drift into floodplains as they are <br />connecting with the river (Modde et al. 2001). Bonytail spawn and recruit in floodplain <br />16 ~ <br />