Comparisons of Two Bluegill Populations by Means of the RNA-DNA Ratio and Liver-Somatic Index

Abstract

Bluegills (Lepomis macrochirus Rafinesque) from two central Tennessee lakes revealed monthly and seasonal variations of liver RNA‐DNA ratios (liver RNA/DNA) and liver‐somatic indexes (LSIˈs) that were associated with gonad maturation, spawning, and temperature. Liver RNA/DNA indicated a longer summer growth depression in fish collected from the smaller, shallower lake. Although LSIˈs were consistently higher in the smaller, shallower lake, liver RNA/DNA and scale analyses showed faster growth rate in the larger, deeper lake. Thus the LSI may be a useful indicator of relative food intake‐energy storage levels within a single lake, but it does not necessarily reflect absolute growth rate of the fish. Liver RNA/DNA provided an indication of immediate or short‐term growth rates.

Use of vitamin C as an immunostimulant. Effect on growth, nutritional quality, and immune response of Labeo rohita (Ham.)

“…Whole-body carcass composition was higher for Exp-2 feed-fed fish than for control fish, which revealed the overall low feed-utilization level. Tissue RNA concentration and RNA:DNA ratios have been used as indicators of the recent growth or nutritional status of fish (Bulow et al 1978;Miglavs and Jobling 1989;Mitra and Mukhopadhyay 2002). The RNA:DNA ratio indicates metabolic intensity which is deeply influenced by the nutritional status of the diet (Clemmensen 1987).…”

Seasonal changes of periphytic nutritive quality for Sicyopterus lagocephalus (Pallas, 1770) (gobiidae) in three streams of Reunion Island

“…Mobilisation of the hepatic reserves results in a weight loss of liver (Allen & Wootton 1982, Lahti & Muje 1991. After spawning, the liver weight increases faster as the food intake is significant (Bulow et al 1978, Allen & Wootton 1982, Tveranger 1985, Crupkin et al 1988, Singh & Towheed 1993. In fact, except during reproduction, the hepatosomatic index is considered in fish as a good indicator of both food consumption and energy stock.…”

Comparison of growth and RNA: DNA ratios in three populations of juvenile turbot reared at two salinities

“…The RNA : DNA ratio has been used to investigate the effects of sub-lethal toxicant exposure on growth , the influence of ration size on growth (Bulow, 1970), seasonal variation in growth (Bulow et al, 1978), and the effect of age and temperature on growth (Goolish et al, 1984;Mathers et al, 1993).…”