While researching the genetic influence of introduced Florida bass on a small fishery in East Texas, scientists noted something unexpected and especially interesting for bass anglers.
Bass seem to grow bigger when they have a small home range and don’t move much.
“We had lots of variability within the bass population,” said Dr. Brian Graeb, a biologist at South Dakota State University and part of the research team for 125-acre Grand Lake at Eagles Nest Preserve east of here. “We began studying why. We started to look at habitat use and movement by putting radio telemetry into 40 bass and did an 18-month study on home ranges of movement.”
As he tracked the bass, Ph.D. student Jason Breeggeman discovered that some areas of the lake were heavily used, while others were not. He also noted a wide variance in how far bass swam.
“The smallest mover had a home range of about 50 yards, and this is what we would normally expect,” Graeb explained. “But we began to see bass the used the entire lake, routinely zipping over a mile to each end of the lake. In 24 hours, one bass swam 1.4 miles and we had one go more than 2 miles.
“These were very unexpected results.”
In trying to figure out why some stayed home and others didn’t, they scanned the bottom of the lake, seeing that much of the woody cover had disintegrated. With remaining habitat limited and occupied, some bass had no choice but to move to find food.
“We determined habitat was the most limiting factor in this lake,” Graeb said. “It was like we had a bunch of marathon runners and we wanted couch potatoes. The bass were skinny by having to swim so far.”
Researchers now have added artificial habitat from Mossback to form “fish cities” throughout the lake and will monitor the results.
“The goal is to try and decrease fish activity, decrease their home range and increase consumption,” the biologist said. “Our target is between 20- and 40-percent coverage of the lake. Currently, we have 22 fish cities and 13-percent habitat coverage with a plan to increase annually. We want to see if too much habitat begins to be too much of a good thing.”
The project began in 2011, with a goal of determining how best to grow a 15-pound bass by maximizing genetic potential and other variables.
“We came up with a strategy for trophy fish management based on age, habitat, nutrition and genetics,” Graeb said. “These are all barriers that must be overcome to grow big fish.”
After learning that genetics were favorable, scientists noted that bass diet consisted of nearly an equal amount of crawfish and forage fish. They also observed that the fish first put on weight quickly, but then leveled off as they aged. Eventually, they saw that some of the fish were fat, while others were skinny, which led to the discovery about movement.
(This article appeared originally in B.A.S.S. Times.)