When spring arrives in Colorado, fly fishermen along the Front Range start thinking about bass fishing. Largemouth Bass become active and very aggressive during the spring spawning period which generally coincides with runoff.

Largemouth Bass were first introduced in Colorado in 1878. The largemouth bass is the largest and most popular member of the Centrarchidae family of sunfish and its subgroup known as black bass. Like all sunfish, largemouth are nest builders, spawning in 18-36 inches of water in late spring when water temperatures reach 65° F. Males guard the nest and young for two weeks after the eggs hatch. The diet of bass changes from zooplankton to other food including fish, frogs, and crayfish when the young reach a length of two inches.

Their coloring is mostly green, ranging from olive to dark green on the back and greenish yellow on the sides, with a white or cream-colored belly. A series of dark splotches form a horizontal stripe that extends down the length of the sides along the lateral line. In some circumstances, especially very muddy water, the largemouth may lose much of its coloring, appearing almost white or very light green.

As the spawn approaches in early spring, Largemouth transition from their winter holding patterns in deep water toward shallow spawning sites. Because farm ponds and other small bodies of water warm rapidly in the spring, bass fishing starts earlier there than it does on large lakes and reservoirs. They remain in the shallow water throughout the spawn, though sometimes retreat to deep water near the nests during and shortly after spring cold fronts. Once the spawn is complete, many Largemouth will remain in shallow areas until water temperatures rise above 72 F. Then they often establish summer residence in deeper water, moving shallow to feed early and late in the day, or at night.

Almost all the public ponds and small lakes in and around Boulder have Largemouth Bass in them. You could start with the Sawhill Ponds Wildlife Preserve (18 ponds) owned by the Colorado Division of Wildlife and managed by the Boulder Open Space and Mountain Parks Department. It is located east of the Boulder city limits on the west side of 75th Street, 0.6 mile north of Valmont Road.

Next month we'll talk about tactics and tackle for this great gamefish.

By the way, here's an additional bonus when fishing for Bass: