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1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />predator TL • prey TL interaction term. The form of the size-dependent capture equation was: <br />logit of P(capture) _ -2.2621 - 0.0136(prey TL)Z + 0.0036(predator TL • prey TL) (2) <br />and can be transformed to probability of capture using the formula: <br />P(Capture) = ero$;` of p("rprure) , (1 -), elogit of P(caplure))- t . <br />(~) <br />This analysis demonstrated that red shiners were moderately successful and persistent predators <br />on Colorado squawfish larvae. Probability of capture peaked at about 0.25 for lazge shiners <br />attacking small larvae, and declined to near zero for small shiners attacking lazge larvae <br />(Figure 6). Each time a larva was attacked by a red shiner in a simulation, these equations were <br />used to calculate the probability of capture based on size of prey and predator. <br />Attack Rate <br />Direct estimation of the rate of encounter and the rate of attack given an encounter <br />requires extensive data about the behavior and physical abilities of the species of interest <br />(Gerritsen and Strickler 1977; Bailey and Batty 1983; Fuiman and Gamble 1989). As an <br />alternative, we used a methodology that combined the probabilities of encounter and attack into a <br />single parameter that predicted the daily number of attacks on individual larvae (hereafter called <br />attack rate) as a function of larval size and environmental conditions. Data for estimating this <br />quantity were obtained from studies conducted in outdoor mesocosms. <br />12 <br />