July 05, 2012
Many telemetry studies have investigated largemouth bass movements, but until recently, none had examined the activities of winter bass in waters north of Florida and Mississippi. Dr. Rich Noble and Karle Woodward of North Carolina State University radio tagged 11 adult largemouths in E. B. Jordan Reservoir in the Piedmont region of North Carolina and followed them from late October into the following May.
The bass were captured and tagged in a single 23-foot-deep bay, formed by a tributary creek. Ten bass remained there during the study, though seven made occasional forays outside the bay. Water temperatures during the study ranged from 69F in late October to 42F in late December, before warming to 71F by late April. At normal pool, the bay has sparse cover, consisting of sparse vegetation, small stickups, tree roots, and undercut banks.
As water cooled in fall, largemouths reduced the size of their home ranges. One bass showed no detectable movement from early January through the end of March. It wintered in tree roots at the base of an undercut bank. Bass also shifted farther offshore during the coldest period that ended in mid-February. When water temperature climbed in February, the fish abruptly moved close to the bank.
During winter, largemouths tended to move closer to the bank in the early morning, shifting offshore from about 11 a.m. to 3 p.m., then approached the shore again in the late afternoon, where they remained at night. Once water temperatures rose in spring, the bass stayed near shore day and night.
When water levels rose 6 inches or more, bass entered areas with flooded shoreline bushes and trees. They moved into such cover both during the day and at night, though the shift was most pronounced in fall, late winter, and early spring. Some fish moved into flooded shoreline cover at water temperatures as low as 43F.
Several of the largemouths established separate home ranges during winter, returning to the home ranges they'd used in fall when the water warmed, a behavior that previously had not been documented in adult largemouths, though noted for sub-adult bass. As other studies have shown, individual bass chose home ranges and faithfully return to them, though one bass was a wanderer and didn't establish a home range at any point. Several fish moved to suspected spawning locations and remained there late in the tracking period.
Interestingly, the trackers followed the signal of one bass to an angler's livewell, where the sublegal fish (Jordan with a minimum-length limit of 16 inches) was residing. The angler released the bass.