SPIRIT LAKE, Iowa (AP) — A system for netting and tagging walleye is helping Iowa Department of Natural Resources biologists track and study population trends of the fish that is one of the most popular game species in North America. For 21 years the DNR has netted walleye in Northern Iowa lakes during April to tag them. It has built a database of about 24,000 walleyes. The database allows biologists to track annual abundance, survival and growth rates It also is used to support research projects aimed at improving walleye fisheries.

DNR Biologist Jonathan Meerbeek says the agency bases management decisions, like regulations or stocking rates, on several years of data to maintain adequate fishing supplies. The state’s record walleye catch was 14 pounds, eight ounces, caught in September 1986 in the Des Moines River.