Maturity and Fecundity of Threadfin Shad, Dorosoma petenense (Günther), in Central Arizona Reservoirs
- 1 January 1971
- journal article
- Published by Oxford University Press (OUP) in Transactions of the American Fisheries Society
- Vol. 100 (1) , 74-85
- https://doi.org/10.1577/1548-8659(1971)100<74:mafots>2.0.co;2
Abstract
It is necessary to determine maturity of a fish before accurate fecundity estimates are attempted. Ovary weight divided by the gross body weight (the maturity index) was found to reliably describe stages of maturity for threadfin shad when used in conjunction with size‐distribution of ova in the ovary. Females are incapable of releasing mature ova until ovary weights have increased to 19% or more of the body weight, even though mature ova may be found at lower maturity indices. Threadfin shad spawn once a year in the Salt River reservoirs, with fecundities ranging from 923 to 8,540 ova. Young‐of‐the‐year fish do not spawn in their first growing season, even when attaining minimum spawning size (49 mm) before the end of summer. Older fish spawn nearly two months before age‐I fish, but a second complement of eggs that older fish begin to mature appears to be resorbed rather than spawned. A high percentage of the older fish fail to reproduce, with adipose tissue replacing gametes in the gonads. Percentages of abnormal gonads are relatively low in younger fish.This publication has 0 references indexed in Scilit: