The Tahoe sucker spawns in Pyramid Lake from April to August at lake temperatures of 11.7 to 22.7 C. The spawning population is comprised of a large lake spawning group and a numerically smaller river running group. The river running group is smaller in length and was not considered during this study.
The sex ratio of sampled suckers significantly favored the females. This is the result of the longer life of females and greater mortality of males during spawning.
Pyramid Lake Tahoe suckers reach sexual maturity at two to three years of age; however, those in Lake Tahoe do not mature until four or five years of age. The size at sexual maturity is different in both populations, which suggests that size or rate of growth rather than age determines sexual maturity.
The fecundity of Tahoe suckers is positively correlated with fork length, weight, and age. Additional analysis showed that a better correlation occurred between fish size (either length or net weight) and total ovary weight. We believe that fish size is primarily correlated with total reproductive tissue produced and secondarily with fecundity. A comparison of the Pyramid Lake population and the Lake Tahoe population demonstrated that size, not age, is the most important determinant of Tahoe sucker fecundity.
Kennedy, Joseph L. and Kucera, Paul A.
"The reproductive ecology of the Tahoe sucker, Catostomus tahoensis, in Pyramid Lake, Nevada,"
Great Basin Naturalist: Vol. 38
, Article 3.
Available at: https://scholarsarchive.byu.edu/gbn/vol38/iss2/3