Hatchery-reared fingerlings find a new home. Releasing them into rocky habitat provides access to cover to minimize losses to predation.
March 22, 2024
By Dr. Hal Schramm
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Stocking is a common fishery management tool and is extensively used in black bass management programs. An average of 426,000 fingerlings and 32,000 advanced-size smallmouth bass are stocked annually into lakes and reservoirs in 12 states. Another of 129,000 fingerlings and 10,000 advanced-size smallmouth bass are stocked into rivers and streams in six states.
Although the ranges of largemouth bass and smallmouth bass are approximately the same in the United States and Canada, smallmouth bass stocking effort is far less than the 3 million largemouths stocked annually in 24 states and far, far less than more than 15 million Florida largemouth bass annually stocked in 10 states. Why so few smallmouth stockings? Or maybe, why so many largemouths, and what can be learned from fisheries not supported by stocking?
Where Smallmouths Are Stocked The native range of smallmouth bass extends from the Missouri River Basin in the west to Vermont in the east and from the Great Lakes Basin in the north to the Tennessee River Basin in the south. Smallmouth bass have been introduced beyond their range throughout the continental United States except Florida and Louisiana and into three Canadian provinces. Smallmouths presently are stocked in 13 states. Four states—Alabama, Oklahoma, Tennessee, and West Virginia—have discontinued smallmouth stocking.
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Most stocking occurs in reservoirs, and most of the fish are stocked to supplement existing populations. Smallmouths have been stocked to establish new populations in Arkansas, Kansas, and Nebraska or, in Nebraska, after small impoundments have been renovated. Georgia intensively stocks smallmouth bass into Blue Ridge Reservoir to sustain a population threatened by introduced Alabama bass. North Dakota does not rear and stock smallmouths but occasionally transfers adult smallmouths into new waters to establish populations.
Six states stock smallmouths in streams. Most of this stocking is to supplement existing populations. The fingerlings stocked in Arkansas were “replacements’ for the adult smallmouth collected from the upper Ouachita River to use as brood fish to produce fish for stocking into Lake Catherine. Kentucky stocked 6,320 smallmouths after a fish kill in 2021 but otherwise did not stock streams during 2018 to 2021. Indiana has also stocked after fish kills but has not had the need since 2018.
Effective Stocking: Broad River, South Carolina Broad River, South Carolina Smallmouth bass were first introduced into the Broad River, South Carolina, in 1984, to diversify angling opportunities. The Broad River is an Atlantic slope drainage, and smallmouth bass are not native. As is typical of southeastern streams, spring and summer discharge is highly variable, and natural recruitment is low in high-water years. Stocking offers a way to stabilize recruitment. It is also well established, at least for largemouth bass, that stocking larger fish in the fall yields better survival.
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South Carolina Department of Natural Resources fishery scientist Jason Bettinger led a study to determine an effective way to sustain quality smallmouth fishing in the Broad River. From 2005 to 2010, an average of 10,000 small fingerling (1.7 inches average length) smallmouths were stocked in May and 2,800 large fingerlings (6 inches average length) were stocked in October. The smallmouth population was monitored by electrofishing and angling each year after stocking.
The contribution of the small fingerlings to the population of age-1+ fish (fish in their second year of growth) was low (average 6 percent) in all years; large fingerlings were 1 to 44 percent (average 17 percent) of the age-1+ fish across years but made a greater contribution to the adult population in years of high flow. The low contributions of stocked fish in low-flow years were a consequence of high natural recruitment.
Bettinger’s study demonstrates the effect of flows on natural recruitment, but also provides guidance for effective stocking. Stocking is not needed in low-water years. Stocking large fish in the fall provides a greater return. Fall is also the time when the success of a year-class can be judged and the need for stocking determined. Larger fish are about four times more expensive than fingerlings, but they are also available to stock at a time when population monitoring detects a weak or missing year-class. Of course, fall is too late to begin hatchery rearing. Bettinger suggests rearing fish at the hatchery to large size and stocking if needed. If not needed, they can be added to fish already being stocked into a reservoir. (South Carolina annually stocks smallmouth bass into two reservoirs.) It’s more economical and efficient than stocking a lot of small fish that have low survival and may not be needed if natural recruitment is good.
Lake Catherine, Arkansas Lake Catherine, Arkansas The Ouachita River has been impounded to form lakes Ouachita, Hamilton, and Catherine. Lakes Ouachita and Hamilton have developed solid largemouth and spotted bass fisheries. Lake Catherine, a narrow and riverine reservoir with a lot of flow and little main-lake bass habitat, has developed poor bass fisheries compared to its upstream sister reservoirs. Ouachita lineage smallmouth thrived in the Ouachita River upstream of Lake Ouachita but never established in the lake. Eleven years of stocking both Ouachita lineage and Tennessee lake-strain smallmouth bass into lower Lake Ouachita failed to develop a smallmouth population.
Arkansas Game and Fish Commission fishery biologist Sean Lusk suggested trying to establish smallmouth bass in Lake Catherine, which lacked good bass fishing but appeared to have habitat conducive to survival of the river-loving Ouachita lineage smallmouth bass. Brood stock were obtained from the upper Ouachita River and genetically checked to ensure they were pure Ouachita lineage smallmouth bass. Stocking began in 2019 with 10,000 fingerlings; 35,000 and 48,000 fingerlings followed in 2020 and 2021. This project is an attempt to establish a population, not start a put-grow-take program; stocking will end in 2024. Anglers are already catching some smallmouths, and Lusk remains optimistic. Judging success of this effort will await collection of young smallmouths—evidence of successful reproduction and recruitment—after stocking ceases.
Stocking as a Tool Stocking is a way to increase the number of fish of a species in a fishery. Many anglers think more fish means better fishing and are pleased when they learn of large numbers of fish being stocked. Conversely, many are displeased when fish are not stocked, apparently thinking fewer fish will be available to catch. Fishery managers’ goals match the anglers’ desire: to keep fishing (meaning, catching) good or, when needed, to make it better.
But fishery managers face two important realities. First, essential resources needed to keep fishery management running—personnel, equipment, hatchery space, and funds—are always limited. Second, adding fish to a population does not always result in more fish and better fishing if the environment is unsuitable or already has good recruitment and contains the maximum number of fish it can support.
Stocking is just one of several fishery management tools. And it is an expensive one. While some states reported costs less than 20 cents per fish to spawn and rear fingerling smallmouths, costs are far higher when all personnel costs and amortization of equipment and hatchery facilities are included. The estimated full costs for stocking smallmouth bass are $1.40 for small fingerlings and $5.41 for large fingerlings.
Most of the smallmouth bass stocked are to supplement existing populations. Unfortunately, population monitoring and creel surveys often are insufficient to determine whether populations need to be boosted or whether supplemental stocking actually increases abundance or angler catch rates. This is not necessarily the fault of fishery agency biologists because precision in sampling populations and natural variations in year-class abundance often make detecting actual changes in populations—both declines from insufficient natural recruitment or additions from supplemental stocking—difficult to detect. Thus, supplemental stocking may be necessary and beneficial in some fisheries; in others it may only be stocking to satisfy anglers and the political influence that they can bring to bear on fishery agencies. The same is true for the far greater numbers of largemouth bass stocked.
Conservation Concerns Smallmouth bass are native to streams that flow out of the Ozark highlands in northeast Oklahoma and the Ouachita highlands in southeast Oklahoma. Although smallmouths often thrive in reservoirs, smallmouth populations failed to develop in reservoirs built on these rivers after 50 to 70 years. Following on successful establishment of a smallmouth population in Lake Texoma, which is not within the native range of smallmouth bass, after Texas Parks and Wildlife Department stocked Tennessee River smallmouths, Oklahoma Department of Wildlife Conservation (ODWC) successfully established smallmouth populations in several Oklahoma reservoirs outside the smallmouth native range. Expanding on that success, ODWC stocked Tennessee River smallmouths into Broken Bow and Tenkiller lakes, both within the native range of smallmouth bass, and both lakes where native stream-dwelling smallmouths failed to establish in the reservoirs.
Several years later, researchers at Oklahoma State University determined that smallmouth bass in Ozark and Ouachita highlands streams were genetically unique from other smallmouth bass populations; those in Ozark Mountains streams are the Neosho subspecies, and those from the Ouachita Mountains streams referred to as the Ouachita lineage. The stockings of Tennessee River smallmouths into Broken Bow and Tenkiller lakes established populations. Some fish moved upstream and hybridized with the Neosho and Ouachita smallmouths.
With smallmouth fisheries successfully established in several other reservoirs and the potential for adverse effects on Neosho and Ouachita populations, all future smallmouth stocking was terminated. Unfortunately, anglers continue to move smallmouths from established populations in Chimney Rock and Skiatook lakes into Grand Lake o’ the Cherokees, which is in the Ozark highlands drainage where Neosho smallmouths are native. Anglers catch a few smallmouths at Grand Lake, but biologists have not yet observed natural reproduction.
More Than One Smallmouth Bass Taxonomy—the science of classifying fish to an agreed-upon taxon, such as a species—is a blend of well-established rules and data-based opinions. Since 1940, two subspecies of smallmouth bass were recognized: the northern subspecies, Micropterus dolomieu dolomieu, widely distributed throughout much of the native range, and the southern or Neosho subspecies, Micropterus dolomieu velox, in the streams of the Ozark highlands of Arkansas and Oklahoma.
In an Oklahoma State University study published in 1998, researchers provided evidence for a third genetically distinct group of smallmouth bass, referred to as the Ouachita lineage, in the Ouachita highlands and the Ouachita River basin of southwestern Arkansas and eastern Oklahoma. Subsequent research employing next-generation genetic techniques suggests additional genetic stocks are present among these Ozark and Ouachita highland populations that may warrant recognition as additional subspecies.
Meanwhile, genetic assessment of the northern subspecies throughout much of its vast range indicates expected genetic diversity but nothing suggestive of separate subspecies, despite the presence of smallmouth bass in some lakes with widely different body shapes from those in other waters, what biologists call morphotypes.
Although resolution of the subspecies or strains of smallmouth bass awaits, the ecological importance of these different groups is significant. A taxon, in this case a subspecies or lineage, isolated for several thousand years or longer from other similar species often has genetically coded adaptations that make it most fit for survival in the range of environmental conditions of the waters it occupies. In the case of Neosho and Ouachita smallmouths, these adaptations may include tolerance of higher water temperatures and intermittency of water flow, conditions increasingly experienced as temperature climbs and precipitation patterns change to fewer but more intense rainfall events. Preserving these adaptive advantages can only be achieved by not introducing fish that, through hybridization, would alter the best-adapted gene pools and eliminate these beneficial adaptations that may be useful for ensuring perpetuation of these and other smallmouth bass stocks today and into the future. Think of it as a diversified portfolio.
An Unfortunate Need for Stocking Chatuge, Nottely, and Blue Ridge reservoirs in northern Georgia Chatuge, Nottely, and Blue Ridge reservoirs in northern Georgia are within the Tennessee River drainage, and smallmouths are native to the streams impounded to build these reservoirs. Excellent smallmouth bass populations developed in these three reservoirs—without stocking—after impoundment. Unfortunately, Alabama bass, formerly considered a strain or subspecies of spotted bass but now recognized as a separate black bass species, were introduced by anglers into these reservoirs. As a result of competition and hybridization with Alabama bass, smallmouths were extirpated from Chatuge and Nottely in less than 20 years and are being hybridized to extinction in Blue Ridge.
Georgia Department of Natural Resources now maintains a heavy annual stocking of smallmouth bass into Blue Ridge where some pure smallmouths remain. While annual stockings averaging more than 43,000 fingerlings and 600 larger fish seems like a lot of fish for a single, 3,300-acre lake, it is far short of the 82,500-fingerling annual stocking target Georgia DNR fishery scientists consider necessary to maintain pure smallmouth bass in the last native population of smallmouths in Georgia. Achieving the stocking target is impaired by inability to collect adequate numbers of pure-smallmouth broodfish, reported Chris Harper, DNR Assistant Fisheries Chief. To achieve a better return, DNR plans to shift from stocking fingerlings to fall stocking of advanced-size fish.
Looking Ahead There is information in the states that do not stock smallmouths, like Minnesota. In response to my survey to obtain stocking data, DNR Fisheries Section Manager Brad Parsons replied simply: “Recruitment is not a problem in Minnesota waters.” I would add a clarification to that: recruitment is not a problem in Minnesota waters—and those in other states—that sustain smallmouth bass populations. Not all lakes and rivers within the smallmouth bass range have smallmouth bass populations. Why that is remains unknown, but it is likely habitat related. It is tempting to think rocky habitat is important, and there is some good biology to support that. But then there are lakes like St. Clair that are chock full of smallmouths but lack rock.
Rearing hatchery-spawned smallmouths to “advanced” size for fall stocking is expensive, but the substantially greater survival compared to stocked fry warrants the effort and expense. Maybe the significant difference between largemouth and smallmouth stocking is the end game, the reason for stocking. The 13 million Florida bass stocked into waters in nine states outside of Florida are stocked with the sole purpose of providing trophy largemouth bass to anglers. Fishery scientists have demonstrated the benefits of maintaining the genetics of local populations and forewarned of the dangers of mixing Florida and northern largemouth bass. Their science is not wrong.
Fortunately, the widespread introduction of Florida bass into northern largemouth bass populations has yet to have an observable adverse effect. In contrast, smallmouth bass managers are adhering to a growing conservation awareness in waters within the native range of smallmouths by using only local fish for brood stock and, where necessary, conducting genetic testing of brood fish to ensure that the progeny are compatible with the native fish in the system.
In response to my state-by-state stocking query, Pat Black, Tennessee Wildlife Resources Agency Reservoir Program Coordinator, replied, “We discontinued stocking smallmouth in Tennessee. In places with good smallmouth habitat, they do a pretty good job of stocking themselves.” I would only add that where smallmouth stocking is deemed necessary, only native fish should be used as brood stock.
In-Fisherman Field Editor Dr. Hal Schramm is former leader of the USGS Mississippi Cooperative Fish and Wildlife Research Unit at Mississippi State University. An avid angler, scientist, and educator, he often contributes articles on fishery conservation and management.
