Great Basin Naturalist


Sex ratios for tui chubs (Gila bicolor), obtained from a sample of 3,384 fish, deviated significantly from the expected 1:1 ratio (chi-square, P < 0.05). Spawning occurred from June to August, with estimated fecundities ranging from 6,110 to 68,933 ova. Females spawned after attaining a maximum (average) gonadal somatic index (GSI–percent gonad weight/total body weight) of 9.1 percent and between surface water temperatures of 15.5 to 22.2 C. Males reached sexual maturity at age two, with most females maturing at age three. Consistent increases in fecundity were apparent with increasing length, weight, and age. Linear regressions between fork length and fecundity and weight and fecundity were highly significant (P < 0.05).