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Hybrid Hype

Posted Jul. 1, 2001

Hybrid fishes occur naturally and are raised in hatcheries. Many hybrids have lower fertility but seem to exhibit better growth rates and catchability than the parent species. These attributes can help fishery managers achieve certain goals. Hybrids generally take on physical traits intermediate to that of their parents.

Perhaps the most familiar hybrids are those of sunfish species, particularly bluegill (Lepomis macrochirus) x green sunfish (L. cyanellus) and bluegill x redear sunfish (L. microlophus) crosses. These hybrids occur naturally where both species occupy the same habitat, and they are produced by some hatcheries. The first generation (F1) crosses are popular sportfish; however, increased vigor is reduced in hybrids beyond the first generation. Pond managers interested in establishing a trophy sunfish pond where no fish are present could consider stocking F1 hybrids from a reputable hatchery or single sex adults to spawn F1 offspring. Because of their low reproductive capacity, these hybrids should not be used where the primary goal is largemouth bass (Micropterus salmoides) production.

Another familiar "hybrid" is the northern largemouth and Florida largemouth bass cross. The northern and Florida bass are subspecies of the same species, but the F1s exhibit hybrid vigor and are responsible for many state-record fish. Four of the top five trophy bass recorded by the Oklahoma Department of Wildlife Conservation are hybrids. Unfortunately, it is impossible to distinguish northern and Florida bass by their appearance, so there is great room for identification error by all but the most meticulous hatcheries. Managers interested in introducing Florida bass genetics should rigorously evaluate their source.

No natural offspring of white bass (Morone chrysops) x striped bass (M. saxatilis) crosses are known. So-called wipers are produced through artificial propagation in hatcheries and are believed to be sterile. These popular game fish that are stocked by state fisheries departments can grow to 10 pounds or more in five to six years; wipers are also used in aquaculture. They are difficult to distinguish from either parent species.

Another hybrid game fish artificially propagated specifically for sportfishing is the saugeye (sauger [Stizostedion canadense] x walleye [S. vitreum]), which is considered among the best eating of freshwater game fish. They are larger than the sauger but smaller than the walleye; the U.S. record saugeye weighed more than 15 pounds.

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