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Can a lake be FISHED OUT

by DC Staff

Is it possible to “fish a lake out?”

It’s a complex question. And the answer… yes and no.

There are certainly instances where fish populations in lakes small and large have been impacted by angler activity. One need look no farther than famous Mille Lacs Lake in central Minnesota, which, last August, was shut down to walleye fishing for an indefinite time. (It will open again this spring, but only to catch and release walleyes.)

That action on Mille Lacs was the result of over-harvest, but there were also other factors involved, including Indian netting, lack of reproduction, inadequate forage and mismanagement.

But what about waters in the Dakotas? Are they vulnerable to overharvest? Can fishermen impact the resource enough in our generally rural culture to reduce various fish species to the point there is little left?

There are examples.

The Big Perch Raid

The first that comes to mind is Devils Lake yellow perch the last half of the 1980s. At that time, the lake was at a high point in yellow perch production. Fish from 1 to 1 1/2 pounds were dirt cheap. No limits. Anglers loaded not just buckets of them from the winter water, but pickups. At a point, conservative anglers began screaming for limits, despite assurances from biologists that the lake was large enough and there were so many fish, the population wouldn’t likely diminish.

But it did.

Big time.

And then, finally, limits were declared and the lake has made a slow, but steady climb back to a strong perch population once again.

So, if you can fish a lake down like massive, productive Devils Lake, can it happen elsewhere?

Certainly. And it has.


Mother Nature’s Hand

Fishing pressure is a factor, but when you connect it with nature’s inconsistent patterns, the most powerful of which is drought, changes can happen quickly. Most fish species grow slowly and can be taken from the system in an instant. And in the case of panfish, they are short-lived.

Smaller lakes, the mid-size versions, are indeed, susceptible to being “fished out.” When you consider how quickly word spreads of a good perch bite occurring in winter months, then see hundreds of anglers pulling limits daily, well, it doesn’t take long to have an impact.

Anglers look at the situation one way, biologists another. Each lake is different, and there are so many different factors involving fish production in a given body of water it’s often impossible to predict the situation from one year to the next.

We’ve all experienced it: A hot perch bite on a winter lake for a time, perhaps weeks, then suddenly it’s gone. (See story on Reule Lake this issue.) When we witness the number of anglers fishing the lake over an extended period, as anglers we quickly assume it’s been “fished out.”

“That’s a common saying from fishermen when a hot bite cools off, but it’s misleading,” says North Dakota fisheries biologist Paul Bailey, who conferred with biologist Scott Gangl to provide information for us on this complex issue. “To say a lake was ‘fished out’ implies that all or most of the fish were harvested by anglers. In reality, there are a number of factors that cause a bite to slow down.”

The biologists continued: “For a lake to be truly ‘fished out’, anglers have to harvest so many fish that the population of fish is greatly reduced and can’t easily recover. Some of the booming perch fisheries that popped up in the late 1990s might fit this description. That perch boom occurred when our daily limits were much more liberal than they are today, and anglers likely played a major role in reducing many of those booming perch populations.”

However, they clarified, drought played a role in the recovery of many of those lakes in that time period. Low water levels reduce perch and other fish spawning habitat, preventing them from making a comeback. Stocking helps, of course, but it takes a long time for fish to grow, and mortality on stocked fish is high. Thus, when a lake’s fish population is reduced, for whatever reason, it’s a slow comeback.


Fishermen and Science

The Dakotas share similar water and similar problems, a strong issue of which is angling pressure. Here again, however, biologists approach the issue differently than anglers.

The eastern Glacial Lake of South Dakota get a lot of attention from fishermen. These numerous waters not only hold popular yellow perch, but many other attractive species. We asked Webster fish manager and Dakota Country staff writer Brian Blackwell for his thoughts.

“I’d say it’s possible to fish a lake to a point where fishing (catching) becomes difficult,” he said. “Our best example occurred at Hazeldon Lake. Anglers harvested approximately 75 percent of the estimated walleye population in a 1 1/2-month period. Fishing became difficult and anglers stopped coming to Hazeldon.”

A familiar scenario all across the Dakotas in winter. Hot bites come and go, often quickly, especially where yellow perch are concerned.

But why don’t daily and possession limits help keep the situation in check?

“You rarely see a hot perch bit occurring during two consecutive years,” Blackwell continued. “This is likely because of the number of fish removed by anglers, but also natural mortality often removes a high percentage of adult perch. In many lakes, perch are short-lived, often not living longer than 3 or 4 years.”

Blackwell emphasized that each lake is different, and as a result of that, species react differently as well. Some live longer, some not. Some species pull off an amazing year-class of natural reproduction, a hot bite follows for a year or two, then it’s gone.


Oahe Crappies

A beautiful example of that right now are the abundant 13- to 15-inch crappies in Lake Oahe. They’re trophy crappies by any measure, and winter anglers are enjoying them. They’re found throughout the system, from the headwaters of Oahe south of Bismarck/Mandan, all the way to Pierre and points in between.

“These fish,” says Pierre fisheries biologist Mark Fincel, “are likely the result of a 2009 reproductive burst that had all the needs of these fish to pull off a record spawn.”

Asked if, given the growing popularity and pressure on these fish each winter, this crappie population could be hurt in massive Lake Oahe. Fincel doesn’t see it as a problem, but not because of potential overharvest.

“There are so many of them (crappies) in the system right now,” he said. “Those fish are 7 years old and they’ll soon start dying of old age. Seven years is pretty old for a panfish.”

Additionally, with limits in place on crappies in the Dakotas, 10 daily in North Dakota and 15 daily in South Dakota, the resource has added protection. But Mother Nature will soon take its course, Fincel said, and these large crappies from 2009 will become infrequent until another year-class explodes.

Different species of fish, particularly panfish, react in widely different ways to their environment. This is illustrated in both North and South Dakota. Most panfish don’t make age one.

“Crappies are another species subject to Mother Nature’s control more than our own,” said North Dakota biologist Paul Bailey. “Our surveys show very good crappie reproduction in most years, but those young seldom survive through their first winter. This limits the abundant of adult crappies.”

Stocking is important, and fish managers determine which lakes get which fish on annual test-netting, among many other factors, but if a lake gets “fished down”, that doesn’t mean it can just get a heavy dose of more fish from the hatchery and everything will be okay.


Ongoing Research

Blackwell said research is an ongoing project among biologists in regards to improving fisheries.

“In general, we don’t change how we do business when it comes to stocking,” Blackwell said. “In waters that we are able to sample annually with gill nets and fall electrofishing, we follow a dynamic stocking schedule for walleyes in that we will stock if we fail to see numbers of young-of-the-year walleyes during fall electrofishing or there are not a lot of fish in the younger year classes in our net samples. In many other waters, we generally stock walleyes on an every other year schedule.”

If you’re a winter angler in particular, you’ve experienced the problem. A strong fish bite dies rather quickly, and it’s easy to assume it’s been “fished down”, if not “out.” But, that happens even on lake where fishing pressure is minimal.

An example of that are the small twin Arroda Lakes west of Washburn, North Dakota along the Missouri River. Each lake, at about 15 acres, has experienced ups and downs in fish numbers over the many years of their service, but generally they’ve been popular and productive.

About a half dozen years ago, West Arroda was almost suddenly producing giant crappies. They were so big they were even hitting crankbaits. Word got out, the lake got a lot of attention because of these large crappies. Conservative fishermen will say it was “fish out”, but biologists are quick to add more to the equation.

A group of jumbo crappies (or jumbo perch) only occurs every several years, mostly as result of Mother Nature.

“When conditions are right and we get a good year class to survive to adulthood, those single year classes often produce booming crappie fisheries that fly under the radar of most anglers until they reach a desirable size. We’ve seen this on Pipestem and Jamestown Reservoirs, and also our smaller lakes like the Arrodas. Those crappies really went unfished until anglers discovered them and began targeting them. When word spreads of a hot crappie bit on small water like the Arrodas, fishing probably doesn’t have a huge impact on those populations, since their replacement year classes occur so sporadically. Even on larger waters like Pipestem Reservoir, we realized that anglers will target the occasional strong year class and will continue to mine that year class until it’s great reduced.”

As a result of problems like this, the North Dakota Game and Fish Department reduced the statewide crappie limit further from 20 to 10 daily to protect year classes of fish.


Temporary Transplants

It works this way with all species of fish, including walleyes, of course, but as everyone knows, also with forage like rainbow smelt. Good reproductive years are separated by several years of marginal production.

I remember an instance on Brush Lake in central North Dakota in the late 1980s. Bluegills, which were not in the lake, were introduced as stunted fish from another overcrowded lake. Growth on these “new” bluegills in Brush Lake took off in amazing fashion. With a year or two, bluegills approaching 2 pounds were discovered by anglers. Beautiful creatures, they were.

While fishing pressure on them increased moderately, the cycle ended within a few years and most of those bluegills simply died of old age.

So, how do walleyes fit into the picture of overharvest?

“When it comes to our booming walleye fisheries, our management approach is slightly different,” said Bailey. “Since most of our walleye lakes, and particularly the natural lakes in central North Dakota, don’t have natural reproduction, we can control numbers through stocking. Over the last 15 years or so we’ve really learned how productive our prairie pothole lakes can be. Over that time, many duck sloughs have transformed to large, deep natural lakes teeming with forage like fathead minnows. We’ve learned that if we stock walleyes in these lakes, we’ll get catchable walleyes in as little as two years. These growth rates are off the charts and unheard of for walleye fisheries anywhere!”

Thus, in the case of walleyes in small lakes, stocking is the main management tool because of lack of natural reproduction. As a result, the program comes full circle when anglers harvest those fish.

Some long-timers may remember the great walleye bite on Lake Oahe in the mid-1990s. Fish from 3 to 5 pounds were common at that time, the result of one of those special year-classes that took hold amidst abundant forage. Most anglers were keeping those fish, despite cries from conservationists who predicted it wouldn’t last. It didn’t last, of course, but while anglers took a large proportion of those fish home, another larger proportion, biologists point out, died of old age.


There’s No Formula for All

There are situations when lakes are “fished down” or “out.” Panfish don’t live very long, predator fish longer. It’s the (difficult) job of fish managers to try to keep things in balance.

“One of the benefits our biologists have is our ability to sample the fisheries after the boom fisheries go bust, and the ability to assess what remains of each fish population,” Bailey said. “In many cases, walleye populations are reduced in number (this is important for the recovery of the forage base), but are no way near ‘fished out’. In fact, in many cases walleyes remain at above-average numbers, but simply stopped biting.”

In the end, that’s a big part of what keeps us, as anglers, in the game.