Development, validation and field application of an RNA‐based growth index in juvenile plaice Pleuronectes platessa

Abstract

A general mechanism relating RNA concentration and growth rate is derived from four physiological assumptions and developed into a growth index for juvenile plaice Pleuronectes platessa. The index describing instantaneous growth rates (G, day −1 ) in the laboratory with the lowest Akaike information criterion with small-sample bias adjustment was a function of RNA concentration (R, g RNA g −1 wet mass ), temperature (T , • K), body mass (M, g) and DNA concentration (D, g DNA g −1 wet mass ):RNA concentration began to respond to changes in feeding conditions within 8 days, suggesting that the index reflects growth rate in the short-term. Furthermore, the index distinguished between rapid growth and negative growth of juvenile P. platessa measured directly in laboratory and field enclosures, respectively. An application of the RNA-based growth index at two beaches on the west coast of Scotland suggested that the growth of juvenile P. platessa varies considerably in space and time and is submaximum in late summer.

Shifts in nursery habitat utilization by 0-group plaice in the western Dutch Wadden Sea

“…Furthermore, there is no strong support for size-selective predation by fishes and birds on 0-group plaice in summer (van der Veer et al, 1997). The results of this study are also in line with previous observations for the Balgzand intertidal (Teal et al, 2008;van der Veer et al, 2010), as well as for a number of European nurseries (Ciotti et al, 2010;Freitas et al, 2012;Ciotti et al, 2013a,b). This again suggests that variations in food conditions and hence growth potential cannot explain the shifts in habitat use between 1986 and 2009.…”

Evaluation of nucleic acids and plasma IGF1 levels for estimating short-term responses of postsmolt Atlantic salmon (Salmo salar) to food availability

“…Our fish lost weight after 7 days of fasting and repeated measurements of individuals indicated that RNA/DNA values also decreased within this time frame. Decreases in RNA/DNA and RNA concentration have been observed after 1-14 days in a variety of juvenile fish (Loughna and Goldspink, 1984;Lowery and Somero, 1990;Arndt et al, 1996;Stierhoff et al, 2009;Ciotti et al, 2010). A differing response time of RNA/DNA to fasting is most likely due to temperature, species, developmental stage, and amount of fat stored (i.e., resistance to fasting).…”

“…Of the four indices we measured in this study, RNA/DNA was the most highly correlated with short-term growth rate. In sexually immature fish, an index that reflects protein production should be appro- (Malloy and Targett, 1994;Stierhoff et al, 2009;Ciotti et al, 2010). The differing response times to refeeding is most likely linked to varying lengths of time fasted before food was re-introduced, to sizes of the fish, and to developmental stage or species.…”

“…Restoration managers require tools to both assess whether hatchery-reared fish are thriving in the natural environment and to assess the condition of native postsmolts. Identifying a minimally invasive, nonlethal method to provide an index of growth rate or nutritional state in postsmolt AtlanCaldarone et al: Biological indices of growth rate and nutritional state of Salmo salar 289 tic salmon would allow restoration managers to evaluate the condition of field-captured fish.Since their first application in the 1970s, RNA-based indices have been used to determine the nutritional state and growth rates of larval and juvenile fish in both the laboratory and field (Bulow, 1970;Buckley, 1979;Buckley et al, 1999; Gwak and Tanaka, 2001;Vasconcelos et al, 2009;Ciotti et al, 2010; among many other studies). Juvenile fish grow rapidly through accretion of protein, and the amount of RNA in a cell is a measure of the capacity of a cell to synthesize protein (Millward et al, 1973).…”

“…Since their first application in the 1970s, RNA-based indices have been used to determine the nutritional state and growth rates of larval and juvenile fish in both the laboratory and field (Bulow, 1970;Buckley, 1979;Buckley et al, 1999; Gwak and Tanaka, 2001;Vasconcelos et al, 2009;Ciotti et al, 2010; among many other studies). Juvenile fish grow rapidly through accretion of protein, and the amount of RNA in a cell is a measure of the capacity of a cell to synthesize protein (Millward et al, 1973).…”