AbstractAn underwater closed‐circuit video system was used to remotely monitor and record the behavior of bluegills (Lepomis macrochirus) and redear sunfish (Lepomis microlophus) guarding their nests before, during, and after applications of aquatic herbicides. Nests were sprayed to achieve a nominal concentration of 4 mg/L of either a dipotassium salt of endothall (Aquathol‐KD̊), a dimethylamine salt of 2,4‐dichlorophenoxyacetic acid (2,4‐D), or water (control). No significant differences in rates of nest abandonment existed among the three treatments (p>0.10). Abandonment averaged 5.17 min for both species and herbicide treatments, whereas the herbicides persisted in the water column for at least 45 min. When abandonment occurred, congeners nearly always intruded on the nest to feed on eggs or fry. After spraying, the adjusted mean frequency of rim circling, fanning, and agonistic behaviors exhibited by bluegills guarding eggs did not differ among the three treatments (p⩾ 0.35). These results suggest the two herbicides will not elicit pronounced shifts in reproductive behavior of sunfish when they are proper
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