Will the walleyes survive

[Lee Borgersen]

               Will the walleyes survive?   .....

Posted on November 2, 2013
 

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This year’s fry look great — but can they make it to keeper size?

"It’s no secret that there’s a shortage of small walleyes in Mille Lacs Lake at the moment. The 2010 through 2012 year classes are at historical lows, and even the 2009 year class is “below average” according to DNR Aitkin area fisheries supervisor Rick Bruesewitz."
 
Even so, Mille Lacs Lake is busting with healthy species. Northern catch rates in the fall gill nets were the highest since 1983, and the smallmouth bass numbers were also over the top. After five years without a significant heat kill, tullibees are, at the very least, holding their own.

About the only fish that aren’t currently thriving in Mille Lacs Lake are the perch and the walleyes.

Unfortunately, Mille Lacs Lake is known (arguably famous) for walleye and perch.

The one big, gleaming bright spot in all this can be found in the nursery.

As Bruesewitz stated in his letter to the Mille Lacs Input Group in early October, the 2013 young-of-the-year walleyes are abundant, and big. The young-of-the-year perch count was also high, the highest seen since 2006.

In 2012 the young walleyes caught in last year’s gill nets measured between 3 and 7 1/2 inches, for an average of about 5 inches.

This year there were a higher proportion of young walleyes over 6 inches and far fewer walleyes under 4 inches. This year’s average young-of-the-year walleye was a little better than 6 inches long.

That might not sound like much to an angler, but to a biologist, it’s significant.

“That extra inch makes a big difference,” Bruesewitz said. “It doesn’t guarantee their survival, but typically it gives them a far better chance.”

Bruesewitz was quick to point out that there were initially strong year classes for 2010, 2011, and 2012 walleyes, but the young fish disappeared between the fall gill net surveys and the following spring surveys. The difference this year could be (stress “could”) that the young walleyes are bigger, and there’s an abundance of non-baby-walleye forage in the lake at the moment.

“We’ve had an abundance of big baby walleye in the lake before, but it’s still nice to see,” Bruesewitz said. “It’s fairly common when we have a strong perch hatch.”

According to Bruesewitz, perch and walleyes both eat zooplankton when they hatch. While perch stick to that diet for most of their first year, walleyes quickly give up their vegetarian diet and begin to forage for other young-of-the-year fish, mainly perch.

“Apparently there was enough zooplankton to keep those babies (walleye and perch) well fed,” Bruesewitz said when asked about the effects of zooplankton-eating zebra mussels in Mille Lacs. “And there were plenty of baby perch.”

Bruesewitz warned that even if the 2013 year class does survive in abundance, it won’t make up for three years of poor classes. “We’re not gaining enough to compensate for the losses due to mortality, but the fish are in better condition,” Bruesewitz said. “We could gain some of the biomass back just from the fish being in good shape.”

According to Bruesewitz, it didn’t hurt that the total kill from anglers will likely come in at less than 150,000 pounds, and netting only about 15,000 pounds. “That 160,000 pounds or so did not dramatically negatively affect the fishery,” he said. “It also helped that we didn’t have a dramatically hot summer, and that reduced hooking mortality substantially.”

While Bruesewitz is cautiously optimistic, he’s a long way from saying the 2013 year class is out of the woods. “While it looks good, and they are definitely bigger, we’ve been seeing high mortality for the last few years,” he said. “We’re not certain that they are going to survive.”