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Seasonal changes in 17-ß estradiol of the Rio Grande Chub ( Gila pandora ) in south-central New Mexico

Colleen A. Caldwell·S. Adam Fuller·William R. Gould·Paul R. Turner·Dennis M. Hallford
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Abstract

Timing of gametogensis and thus spawning can be inferred through changes in plasma concentrations of gonadal hormones. In preparation for ovulation and spawning, mean concentrations of 17ß-estradiol in a population of Rio Grande chub ( Gila pandora ) occupying the Rio Bonito, New Mexico, peaked at 37.6 ng/mL on 16 June and declined to 1.50 ng/mL by 11 August. Similarly, the gonadal somatic index (GSI) increased from 9.02 on 21 May ( n = 9) to 11.85 on 16 June ( n = 2) and declined to 6.10 on 11 August ( n = 2). Peak concentrations of 17ß-estradiol and elevated GSI in June coincided with peak daylength for the year (14 h and 12 min) and average water temperature of 15.1°C. Concentrations of 17ß-estradiol remained low through 3 October indicating no additional spawning events in the Rio Grande chub population. We demonstrated 17ß-estradiol is a nondestructive and thus useful tool in estimating timing of spawning in a wild fish population.

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Colleen A. Caldwell, S. Adam Fuller, William R. Gould, Paul R. Turner, Dennis M. Hallford. 2004. Seasonal changes in 17-ß estradiol of the Rio Grande Chub ( Gila pandora ) in south-central New Mexico. https://doi.org/10.1894/0038-4909(2004)049%3C0311%3Ascieot%3E2.0.co%3B2

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