It’s the time of the year when white bass, striped bass and hybrid striped bass group up and chase shad, often corralling them near the surface where they have nowhere to escape. “Schooling” whites, stripes and hybrids can make for some exciting fishing on late afternoons in the summer. Catching these schooling, lure-crushing fish has salvaged more than a few of my black bass outings after sweating through a long Mississippi summer day for only a couple of bites.
Despite the fact that these game fish are appreciated by some anglers, others — particularly largemouth bass anglers — accuse these sportfish of eating and competing with their preferred quarry. Is this the case?
The simple answer is “yes,” but read on.
White bass, striped bass and hybrid striped bass do eat black bass (largemouth, smallmouth and spotted bass), but they eat far fewer black bass than do black bass themselves. Cannibalism is a way of life for black bass. Habitat separation between the black bass and the open-water white bass and their close relatives minimizes their consumption of black bass.
All of these fish eat fish. In Mississippi waters, that means shad. Because they share a common food resource, competition is possible. And this competition could affect growth rates of all competing species.
Although competition is possible, it only occurs when a shared resource is in limited supply. Shad are abundant, and production is high in Mississippi’s fertile waters. With ample forage, competition does not occur, and black bass and white bass and their relatives all grow well.
But varying environmental conditions cause fluctuations in shad numbers. The shad die-off during the unusually cold winter of 2009-10 is recent evidence that environmental conditions can greatly reduce the abundance of shad. High reservoir discharge in the spring can also reduce shad numbers. So, even though shad generally are abundant, there may be years when black bass and the white bass clan compete.
Several years ago, dissension over striped bass stocking in Tennessee reservoirs increased to a boiling point — black bass anglers were “certain” that stripers were ruining their fisheries, and striped bass anglers and a healthy and lucrative guide fishery demanded that striped bass stocking continue. The same bass war was fought at Lake Texoma in the 1980s.
Steve Miranda, a fisheries scientist with the Mississippi Cooperative Fish and Wildlife Research Unit and Mississippi State University, was asked by Tennessee Wildlife Resources Agency to assess the possible adverse effect of striped bass on black bass populations in Norris Lake.
Norris is a predator-rich system containing largemouth, smallmouth and spotted bass, crappie, walleye, and stripers, all of which feed on shad.
Using bioenergetics models and 25 years of historical data, Miranda and students concluded that shad production was, on average, adequate to feed all predators. However, the historical data also indicated that fluctuations in shad production would limit the food supply for the competing predators in three out of five years.
So the stocked striped bass can compete with black bass in some years.
What is the consequence?
If striped bass stocking ceased in Norris Reservoir, the standing stock (the weight) of all other predators combined would only increase 1 to 4 pounds per acre in most years.
More recently in Lake Sharpe, South Dakota, walleye anglers were questioning whether introduced smallmouth bass were adversely affecting walleye growth via food competition. Similar to the Miranda study in Norris Reservoir, South Dakota fisheries researchers combined diet studies and bioenergetics models to assess predation and competition.
The outcome was similar to the Norris study: smallmouth do not adversely affect walleye. But the reason was different. Although Lake Sharpe is a long way from Mississippi, gizzard shad are still important forage. Smallmouth bass ate a few walleye, and walleye ate a few smallmouth bass. Both sport fishes ate young-of-the-year shad and were, therefore, potential competitors.
The bioenergetics models revealed that elevated water temperature, not competition with smallmouth bass for shad, was what slowed walleye growth. The shad not only fueled smallmouth and walleye growth, but they also provided an abundant and readily available forage supply for the fish-hungry smallmouth. Lacking shad, smallmouth may have taken a heavier toll on the walleye.
Similar to Norris Reservoir, reduced production of shad could substantially change the outcome of this predatory drama.
Whether the fishery is in Tennessee, South Dakota or Mississippi, the standing stock of sport fish is limited by available forage. The different fish-eating sport fishes often feed heavily on shad and, therefore, potentially compete. However, shad are productive and abundant and, in most years, provide ample forage for all sport fishes. They also provide a readily available food supply that helps minimize one sport species preying on another. Clearly, shad have a lot to do with the quality of many fisheries.
Do white bass, striped bass or hybrid striped bass adversely affect the growth and abundance of black bass in Mississippi waters? Maybe, in some years, but not enough to notice.
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