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%. Threeyear-old SR103 females weighed from 1,300 to 2,800 g and had GSIs ranging from 2% to 14%. Only about 10% of the 2-year-old SR103 females had GSI values similar to the expected level for fish ready to spawn. Plasma estrogen concentration was a more reliable predictor of GSI than was body weight. Body size was significantly correlated with GSI in 2-year-old USDA-103 and SR103 females but not in 3-year-old SR103 fish; plasma estrogen was highly correlated with GSI in fish of both ages. Plasma estrogen, testosterone, and GSI were markedly lower in 2-year-old fish than in 3-year-old fish in both populations of USDA females. Oral administration of estrogen to 2-year-old USDA-103 females increased plasma estrogen but did not increase ovarian development.

Determination of the Spawning Season of Bigmouth Sleeper in Puerto Rico by Examination of Gonad Maturation and Reproductive Hormone Cycles

“…The secretion of estradiol during ovarian development stimulates vitellogenin synthesis in the liver. Vitellogenins are integrated into developing eggs as phosvitin and lipovitellin, resulting in increased ovarian size and GSI (Davis et al 2005). Data from this study similarly indicate the same progression with an increase in estradiol secretion followed by simultaneous increases in vitellogenin production and GSI.…”

“…Hormones such as 17β-estradiol (estradiol) and testosterone have been used to assess reproductive development in multiple fish species (Zohar and Billard 1984, Foster et al 1993, Holcombe et al 2000, Davis et al 2005, Gross et al 2006, including members of the family Eleotridae (Wang et al 2001). Vitellogenin has been effective for determining onset of sexual maturation and its continued development in female teleosts, specifically by using an enzyme-linked immunosorbent assay (ELISA) (Jackson and Sullivan 1995, Heppell et al 1999, Gross et al 2006.…”

Oocyte Diameter and Plasma Vitellogenin as Predictive Factors to Identify Potential Channel Catfish, Ictalurus punctatus, Suitable for Induced Spawning

“…The rate of growth of ovary during vitellogenesis parallels those reported in other studies on rainbow trout (Tyler et al ) and indicates that considerable energy be required to complete this period of reproductive development. Davis et al () concluded that catfish at younger maturing ages had significant linear correlations between body weights and maturation indicators. Similarly, in this study, oocyte diameters and plasma vitellogenin levels of channel catfish females mimicked the gonadal maturation.…”

Effects of Varying Dietary Protein Levels and Feeding Frequencies on Condition and Reproductive Performance of Channel Catfish to Produce Hybrid Catfish

“…Moore (1986) showed that for older fish, as fish weight increased percent success of spawning and hatch percentage generally increased, and a similar trend was observed in younger fish, but data for the younger fish were not conclusive. Davis et al (2005) also suggested that age rather than size is a more important component of maturation. These authors proposed to expose fish to shortened seasonal changes that mimic increased age combined with intensive feeding of fish, as a solution to overcome age as a limiting factor in brood stock performance (Davis et al 2005).…”

“…Davis et al (2005) also suggested that age rather than size is a more important component of maturation. These authors proposed to expose fish to shortened seasonal changes that mimic increased age combined with intensive feeding of fish, as a solution to overcome age as a limiting factor in brood stock performance (Davis et al 2005).…”