Water clarity, walleyes, and smallmouths.
Applied Science--Water clarity varies among water bodies and over time within individual waterbodies. A common concern among anglers is how to adjust to water clarity. A recent study offers some guidance.
Canadian researchers compared foraging of walleye--a fish-eating predator adapted to feeding under low-light conditions--and smallmouth bass--a fish and crayfish eater that usually occupies well lit habitats--in different lakes with different water color and clarity. * Rather than looking at what's in the fish's stomach, the scientists relied on stable isotope ratios of carbon and nitrogen in the fish's muscle to assess the diversity of forage eaten and whether the fish were feeding in the shallow, littoral zone or the open water.
Walleye foraging changed little with water clarity--they ate the same general variety of foods and foraged in the same part of the lake regardless of water clarity. This makes sense because walleyes are well adapted to feeding in low-light conditions and can adjust their time of feeding to forage in these favorable conditions. Walleye anglers should not be concerned with water clarity but may want to focus their fishing more during higher light times in more turbid water.
Smallmouth bass foraging, however, changed significantly with water clarity. As water became more turbid, they ate a wider variety of prey and foraged in shallower water. This suggests that smallmouth anglers should fish shallower when water clarity declines.
* Stasko, A. D., T. A. Johnston, and J. M. Gunn. 2015. Effects of water clarity and other environmental factors on trophic niches of two sympatric piscivores. Freshwater Biol. 60:1459-1474.
PHOTO STEVE PHILBROOK
Dr. Hal Schramm
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|Title Annotation:||Bits & Pieces: Blending Fishery Science with Everyday Fishing|
|Date:||Dec 22, 2015|
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