Four species of black bass --- Florida, largemouth, smallmouth, and spotted --- vastly expanded their ranges during the late 19th and 20th centuries. Resource managers were responsible for much of that, as they intentionally stocked nonnative fish to establish and/or enhance fisheries. For example, Florida bass went to California and Texas, and smallmouth bass to the Northwest.
Sometimes, though, dispersion occurred naturally or inadvertently, especially for the smaller spotted bass, which wasn’t identified as a separate species until 1929 and still not recognized by many as distinct until the 1940s or later.
Missouri provides a perfect case history of this unintentional expansion with unforeseen consequences. Once confined to lowland ditches and streams to the southeast and west of the Ozarks, they “went everywhere” as reservoirs were built during mid century, according to Jeff Koppelman, a fisheries biologist with the Missouri Department of Conservation.
Today, they’re a prominent species in fisheries such as Table Rock, Bull Shoals, and Lake of the Ozarks, among others
How did they get to the latter, an impoundment on the Osage River, which is a tributary of the Missouri and geographically separate from the spot’s native range?
“It all gets back to us,” said Koppelman.
In 1941, about 90,000 bass --- largemouth, smallmouth, and spotted --- were collected from streams during the low water of summer and taken to hatcheries. They then were released in the fall. Possibly spotted bass were taken to and released from a hatchery in the Osage River drainage.
Additionally, spotted bass were stocked in streams north of the Missouri River in an attempt to supplement the limited fishery.
Today, spotted bass make up about 18 percent of the bass population at Lake of the Ozarks, according to electrofishing surveys. That’s down considerably from the early 1990 and 1991, when they outnumbered largemouths. Most interesting, though, a 5-9 spotted/smallmouth hybrid was caught there in 2012, even though bronzebacks aren’t thought to be in this impoundment that’s more than 80 years old.
Smallmouths, however, do share the water with spots at Table Rock and Bull Shoals, and, in both of those, they occasionally cross-breed, resulting in a fish popularly known as the “meanmouth.” At Table Rock, largemouths make up about 74 percent of the bass population, according to electrofishing surveys. Spots account for 25 percent, with smallmouth and meanmouths the additional 1 percent. Lake record for the latter is 5-10.
Spots there likely migrated into the impoundments from tributary streams after dams were built on the White River. How they managed to get into streams on the east side of the Ozarks is another matter. Did they move up the Mississippi or migrate east from the Osage and Missouri systems, where they were introduced?
Whatever the cause, “20 years ago, we were panicking,” Koppelman said.
Resource managers and anglers alike feared that spots would crowd out and/or heavily hybridize with resident smallmouths in streams such as the Big, Gasconade, and Meramec. And, indeed, some hybrids have been collected in the lower basins of the two latter rivers.
Liberal regulations --- no size limit and no bag limit --- to encourage harvest of stream spots had no biological impact, Koppelman said, since few bass anglers keep fish.
Thus, far, though, eastern Ozarks smallmouths have retained some of their traditional range. Today, the biologist explained, spots seem strongest on the edges of the eastern Ozarks, where the region either borders big rivers or the prairie to the west. Conversely, spots and hybrids are not often found in streams with large springs and high gradients.
For a time after its recognition as a separate species, the spotted bass was considered comparable in fisheries value to the smallmouth and even largemouth bass by some resource managers. That no longer seems to be the case for this smaller, more aggressive, and generally more adaptable fish.
“I don’t know of anyone who wants spotted bass,” Koppelman said.
(A version of this article appeeared originally in B.A.S.S. Times.)