Interacting effects of lure color and turbidity on foraging response by rainbow trout (Oncorhynchus mykiss)

Abstract

Increased turbidity is known to affect feeding of predatory fishes through its effect on prey color, but interactions between turbidity and prey color are not well documented. To determine the effects of turbidity, water temperature, and illuminance on lure color selected by rainbow trout (Oncorhynchus mykiss), investigations were conducted in a fishing pond in Shiga Prefecture (Central Japan) for 11 days during July–October, 2016. Five fishing series with different lures were conducted on each day, eight differently colored lures being used in random order in each series (10-min trials × 8 colors). Generalized linear models, used to explain catch number variations per 10 min (0–6 individuals; Poisson distribution assumed), indicated that turbidity (1.0–13.6 NTU) significantly influenced lure color selection by rainbow trout. Results indicated that brown lures (followed by dark green, black, and gold lures) were most preferred in low turbidity, but least preferred when turbidity was high. In contrast, lures with a greater reflection intensity [pink, orange, and karashi (mustard yellow)] were moderately preferred, regardless of turbidity. Illuminance (1.2 × 10²–2.9 × 10⁵ lux) and water temperature (15.2– 25.5˚C) did not affect lure color selected by rainbow trout, but both parameters negatively impacted the number of individuals captured per 10 min. The findings highlighted the importance of environmental conditions (particularly turbidity) on prey preference by predatory fishes.