As a fisherman and a fish biologist, I am happy to learn that the counterpoint writer from July 18 ("From best to worst in five days on Lake Mille Lacs") had such a memorable day fishing Mille Lacs with friends and family members.

I, too, have had magical fishing seasons in areas with restrictive regulations, and I am usually dismayed when further restrictions take place. However, we must consider a couple of things regarding the roles of anglers and biologists as stewards of fish populations.

First, personal anecdotes are not a substitute for facts — nor will they provide any ability to predict population trajectories.

For example, in the late summer of 2009, I had one of the greatest days of my life after catching several endangered Colorado pikeminnow (the continent's largest native minnow species, which grows to 6 feet long) while fly fishing in the Upper Colorado River Basin. After catching so many adult fish over 30 inches long, I could have come to the dubious conclusion that the population was performing well. Upon closer examination of the long-term sampling data, it became clear that Colorado pikeminnow populations often comprise a few old, large and wild individuals (in the Upper Colorado River Basin) or many young, small and stocked individuals (in the San Juan River Basin).

I admit the "fishery" for many endangered Western fishes is drastically different from the popular walleye lakes of Minnesota. But if my banner day gave me authority to declare the fish recovered and delisted, that would be a mistake for the long-term prospects of the species. And it would ignore other pertinent issues in the system, including invasive species and water development.

One day or even one year of targeted fishing for a species provides only a limited view of a system's ecology. Personal anecdotes are misleading rebuttals to regulations.

The walleye fishery is not some isolated dysfunction in Mille Lacs. Among other things, ecological forces in Mille Lacs must be accounted for, including fishing pressure, treaty rights for walleye harvest, invasive species, smallmouth bass, muskellunge and — gasp! — climate change.

I expect that many fellow anglers recognize these other factors present in Mille Lacs. But if not, take a moment to talk to a biologist from the Minnesota Department of Natural Resources, read the comments on the online edition of the July 18 article (some of them, at least) and discuss the issue with fellow anglers. And keep an open mind.

Second, as regards hooking mortality: absence of evidence is not evidence of absence. I doubt the counterpoint writer actively searched for walleyes that died post-release, especially using standardized transects across the lake or scuba protocols to rigorously answer the question of hooking mortality rates.

This presents entirely new questions each angler must ask themselves and their partners: How much is enough? Is a day not done until you hook every fish you can? Or are three, 10 or 20 fish reason enough to be satisfied? As an angler, I, too, struggle with how to limit my fishing when the bite is hot. But, like patience, other virtues an angler can and should subscribe to include moderation and willpower.

I applaud anglers who are pursuing alternatives to walleye and look forward to reading more about the science behind the fishery that many people treasure. Regardless of the almighty walleye, Mille Lacs still offers great fishing opportunities for several species that, in my opinion, fight harder and taste just as good as fried walleye.

Without a doubt, the science behind fish and wildlife restrictions will continue to be debated, as with every decision Coach Mike Zimmer or Coach Bruce Boudreau make in a Vikings or Wild loss.

Echoing some of former DNR Commissioner Rod Sando's thoughts from July 15 ("Why the DNR is not the protesters' enemy"), I urge you armchair biologists and concerned citizens that when you wish to dispute "unfair" government regulation based on science, you should read the treaty, look in the mirror and take a civic-minded approach to this issue that seeks a healthy walleye fishery to maximize the lake's utility to Minnesotans and visitors.

Or else get your friends or angling groups to compile fish condition metrics of individual fish you catch (i.e., length, weight, location, date) and start turning your anecdotes into data — not Star Tribune commentary.

Nate Cathcart, a Minnesota native, is a researcher with the Alaska Cooperative Fish and Wildlife Research Unit at the University of Alaska, Fairbanks. The opinions expressed here are solely his own.