Predation Risk Influences Reproductive Behaviour of Iowa Darters, Etheostoma exile (Osteichthyes, Percidae)


Department of Biology, 112 Science Place, University of Saskatchewan, Saskatoon, Saskatchewan, Canada, S7N 5E2.


In this study we tested the effects of predation risk on reproductive behaviour of Iowa darters (Etheostoma exile). We recorded the frequency of courtship behaviour (head shaking) and spawning acts for 30 min before and after removing an opaque barrier to expose groups of darters to (1) an empty tank (the before-pike treatment), then (2) a tank containing a pike (the pike treatment), and finally (3) an empty tank (the after-pike treatment). In response to the pike, darters performed significantly less reproductive behaviour than before exposure to the pike. Furthermore, darters performed proportionally less reproductive behaviour in the area in the immediate vicinity of the pike where risk of predation was highest. However, darters continued to occupy the risky area while exposed to the pike. Removal of the barrier in the absence of the pike (the before- and after-pike treatments) had no effect on the overall level of reproductive behaviour, the proportion of reproductive behaviour performed in the immediate vicinity of the pike tank (the risky area), or use of the risky area.