Nature’s fish factory: phenomenal, fragile

When it comes to factory tours, Dirk Peterson, Minnesota’s new fisheries chief, figures his tour rocks, literally.

“You won’t need a hard hat or ear plugs on my tour,” he said with a smile. “Instead, we’ll be on the water - casting lures toward lily pads, bulrush, rock rubble and the rest of the production facility.”

Though many folks don’t view lakes and rivers as factories, Peterson does. He knows they kick out the fish that contribute $4.8 billion a year to the state’s fishing-related economy. He also knows the lakes are incredibly fragile, comprising parts and processes that took thousands of years to evolve.

“You can’t fix a lake with parts from Fleet Farm,” said Peterson. “That’s why we, as a society, must keep nature’s fish factory intact.”

To Peterson, that means maintaining clean water, spawning sites, nursery areas, and the vegetation that provides shelter for some species and ambush lairs for others. “If any of these elements are missing from the production line, fish go missing, too,” said Peterson.

He added that Minnesota’s excellent fishing is not guaranteed and cannot be taken for granted. He said anglers can easily see physical changes in habitat - more lakeshore development, more urbanization of watersheds, more removal of underwater logs and brush in the name of swimming and boating - but it is difficult to detect the subtle interactions beneath the surface.

Peter Jacobson, a DNR fisheries research biologist, explains. “The person who peers into the water and sees rocks covered in a green algal slime may think nothing of it, other than don’t step there because that’s slippery. But a fish manager sees a very different thing in those same rocks. He or she sees the outcome of excessive nutrient-loading, the deterioration of walleye spawning habitat that provides Minnesota’s most cost-efficient way to maintain a walleye population, which is for the fish to simply reproduce naturally.”

Jacobson explained certain algae-laden gravel bars are useless as walleye spawning habitat because the eggs are suffocated in the slime.

“The connection between walleyes and water quality cannot be stressed enough, said Jacobson. “In the century ahead, the lakes that will continue to provide the best fishing are those that remain clean, resilient, and contain all the elements of a complex natural system.”

Peterson, the DNR Fisheries Section chief, agrees. He encourages anglers statewide to get involved in local water policy planning, habitat conservation projects and funding initiatives for water-related conservation. Closer to the water, he encourages riparian property owners to conserve habitat, and to take steps that minimize soil erosion or nutrient loading by maintaining buffer strips or planting deep-rooted vegetation. These actions, as well as helping educate others on the importance of habitat, are in the best long-term interests of the angling and fishing-related business community.

“Minnesota has a very popular and effective $3 million-a-year walleye stocking program,” said Peterson. “Yet we should never forget that 85 percent of the state’s walleye harvest is the result of naturally reproducing wild fish. Therefore, we need to keep those natural factories in good shape. They are the low-cost way to produce fish for they require no labor, no trucks and no gasoline to take fish from here from the eggs to the end of your line.”