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This year’s Rock River walleye run could see delay

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staff, Gazette
April 1, 2013

— Every year, anticipation for the walleye run on the Rock River draws anglers to the river’s banks and dam tail waters.

This year, however, anglers could see a delay in the annual rite of spring.

Gazette outdoor columnist Ted Peck has been keeping a fishing diary since 1976. It includes 25 years’ worth of observations on spawning activity of Rock River walleyes.

Peck said that in 18 of those years, the peak of the spawn was within 48 hours of April 1—that’s today.

Last year was one of the exceptions. Water warmed to spawning temperature—48 degrees—in early March, but the females’ eggs simply weren’t ready. The result, Peck said, was a disorganized spawning run.

This year is another anomaly that Peck can’t explain.

Peck said the moon’s phase plays a significant role if water temperatures and egg development are on track. This year, water temperatures in the Rock were in the low 30s at the March 27 full moon.

If water temperatures were in the mid-40s now, the spawning run would be at its peak, he said. But temperatures aren’t there, yet.

Male walleyes are ready to go, but cold water has precluded the urge to swim upstream to seek out females. Instead, he said, males and females are still in deep-water wintering holes several miles downstream from traditional spawning areas.

His prediction for angling success?

The next significant moon phase is the new moon Wednesday, April 10. Water temperatures will warm between now and then—maybe not to 48, but at least to 45 degrees.

“All things being relative, they will spawn in 45 degree water if temperatures don’t warm to 48, simply because the eggs will be developed,” Peck said. “As noted, the males are ready to go already.”

That means the peak spawning run could still be a week away, he said, adding that spawning activity takes place at night over a rocky rubble bottom with slightly less than moderate current.



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