Effect of Body Size on Fecundity, the Gonadosomatic Index, Egg Size, and Timing of Spawning of Gizzard Shad

Abstract

ABSTRACT The effect of body size on fecundity, the gonadosomatic index (GSI), egg size, and timing of spawning of gizzard shad (Dorosoma cepedianum) was examined in two large Missouri reservoirs during 1987–1991. Fecundity significantly increased with both total length (TL) and weight of gizzard shad. However, neither GSI, mean egg diameter, nor variance of egg diameters were significantly related to either TL or weight. Rather, mean and variance of egg diameters significantly increased with GSI. Egg-diameter frequencies were not consistently different among TL groups of gizzard shad. There was no evidence that TL affected the timing of spawning. Body size may not affect the timing and duration of spawning of gizzard shad as previously suggested.