"Helping" local fishing ponds with stockings from elsewhere could ruin the fishing.
Largemouth bass, bluegills and channel catfish are the predominant species of fish stocked in urban fishing ponds that are associated with housing developments, public parks and industrial areas.
But other species are sometimes available, sometimes even against the plans and wishes of fisheries management personnel.
For better or worse, some anglers insist on "helping" fisheries managers by adding other species to local fishing ponds.
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Depending on where they live, they bring home from other fishing trips a few extra crappies, walleyes, flathead catfish, yellow perch or northern pike and "donate" them to their favorite neighborhood fishing ponds.
While so-called "midnight stockings" can spice up the fishing menu in a pond, it can create huge problems, too.
"It's tough to keep a good balance of predator-to-prey in a small pond," said Tyler Stubbs, a veteran urban fisheries biologist. "Add some 10-inch crappies to a small pond and you may have good crappie fishing for a couple of years, but you may also end up with a pond full of skinny little crappies that never get any bigger than 6 inches. The crappies eat all the little bluegills, start eating all the little bass, and eventually all that's left is stunted crappies."
Larger predators such as flathead catfish have less potential to overpopulate, but if too many of them are released they can overwhelm the baitfish population in the pond and degrade the overall fishing opportunities.
If possibly damaging the fishing potential of an urban fishery isn't enough incentive to discourage midnight stocking of alternate species, here's another:
In many states that act is illegal. Well-intentioned anglers caught wet-handed stocking fish into a public water can face stiff fines.