Relationship of Gonadal Development to Body Size and Plasma Sex Hormone Concentrations in Female Channel Catfish

Abstract Most channel catfish Ictalurus punctatus do not spawn until age 3, which makes the process of genetic selection for desired characteristics time consuming. A simple method for identifying earlier-maturing fish would speed up the selection process. Two- and three-year-old females (U.S. Department of Agriculture [USDA]-103 strain) were used to correlate body weight and plasma sex hormone concentrations with gonadal development. We also examined the potential of reducing the time to maturation with exogenous estrogen. The USDA-103 females are known to spawn at age 2 in a higher percentage than other strains. The body weight of 2-year-old USDA-103 females ranged from 436 to 884 g, and the gonadosomatic index (GSI) ranged from 0.34% to 6.64%. A population of 2-year-old USDA-103 fish that had been hormonally sex-reversed to females (SR103) weighed from 400 to 1,400 g and had GSIs ranging from 1% to 10%. Three-year-old SR103 females weighed from 1,300 to 2,800 g and had GSIs ranging from 2% to 14%. Only...

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