Effects of Diet on Ovarian Development in Largemouth Bass, Micropterus Salmoides
Largemouth bass, Micropterus salmoides, are typically raised on a forage diet of goldfish (Carassius auratus) and golden shiners (Notemigonus chrysoleucas). Such a diet is costly and often poses a number of a management problems. Use of pelleted feeds can eliminate these problems although a lack of knowledge on the specific nutritional requirements of bass, has limited the use of such diets. This study examined the effects of both forage and pellet diets on the reproductive system of the female bass over an annual cycle. Changes in body weight , length and gonad weight were observed. Annual changes in plasma concentration of testosterone and 17!3-estradiol were monitored by radioimmunoassay. The relationship between these parameters were significantly different during the months of March through July. Body weight and length of the forage fed fish were greater than the pellet fed bass. Gonadosomatic index (GSI) was higher in the pellet fed fish indicating that these fish produced more eggs. Testosterone and estradiol levels of the pellet fed bass were higher at almost all times during the annual cycle except in March when the condition was reversed. During the months of March through July, which is the period of ovulation, the pellet fed fish in general had higher GSI and steroid levels. This could indicate that a balanced pellet feed high in lipid and protein provided more energy than forage diet required for enhanced ovarian development.
largemouth bass, fishes, ovarian development, diet, Micropterus salmoides
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