Size‐Related, First Winter Mortality of Freshwater Fishes

To determine if first winter mortality were greater for small than for large freshwater fish, we conducted eight experiments in lakes and hatchery ponds during which fish were measured in late fall and early spring. Overwinter increase in mean length of the bluegill, Lepomis macrochirus, in one lake and largemouth bass, Micropterus salmoides, in another could have been caused by higher mortality of smaller fish. Size‐related mortality was not detected in six other populations–two of bluegill and one each of largemouth bass, green sunfish, Lepomis cyanellus, fathead minnow, Pimephales promelas, and white crappie, Pomoxis annularis. Available evidence indicates that size‐related mortality is probably not a common phenomenon for bluegill and largemouth bass, but it may be important for walleye, Stizostedion vitreum, and sander, Stizostedion lucioperca.