Abstract
The body proximate compositions were assessed in juvenile Coreius heterodon and C. guichenoti from the upstream of the Yangtze River. The migratory C. guichenoti has a higher lipid content (FAT) than the residential C. heterodon. FAT of C. guichenoti showed an interesting pattern of increase, where FAT increased up rapidly and then leveled off as body mass (M) increased above 6.5 g, suggesting that the lipid concentration reaches an upper limit of deposition. In both species, FAT of the smaller individuals was lower than protein content (PRO), but FAT increased more rapidly than PRO as the fish grew. This indicates that more energy was allocated to protein synthesis than lipid in the smaller fish, with an energy allocation shift from protein synthesis to lipid storage as the fish grew. Strong relationships between both FAT and energy content (E) and water content (WAT) were found in both species, suggesting strong predictive power for future application. However, different models for the two species should be used to predict FAT or E by WAT.
Highlights
Fish body proximate compositions are important parameters used in fish ecology and physiology, and are related to feeding status (Sogard and Spencer 2004; Blake et al 2006; Ali et al 2008), seasons (Jonsson et al 1997; Berg and Bremset 1998; Robards et al 1999), habitat (Anthony et al 2000; Dempson et al 2004), and body size (Deegan 1986; Shearer et al 1994; Jonsson and Jonsson 1998, 2003)
This study aims to provide energy prediction models for juvenile C. guichenoti and C. heterodon in the upstream part of the Yangtze River and to determine how the proximate compositions change with body growth in the closely related species with different life-histories
The exponent values of the length-mass relationships of both C. heterodon (3.17) and C. guichenoti (2.93) estimated in this study (Figure 1) were within the general range found for fishes (2.5 to 3.5) in previous studies (Carlander 1969)
Summary
Fish body proximate compositions are important parameters used in fish ecology and physiology, and are related to feeding status (Sogard and Spencer 2004; Blake et al 2006; Ali et al 2008), seasons (Jonsson et al 1997; Berg and Bremset 1998; Robards et al 1999), habitat (Anthony et al 2000; Dempson et al 2004), and body size (Deegan 1986; Shearer et al 1994; Jonsson and Jonsson 1998, 2003). Changes in the proportions of water, lipid, protein, and ash, result in variation of energy storage in the fish body. This might influence performance related to species fitness, such as the chance of the successful reproduction, survival during seasonal food shortages, and avoidance of predation. The contents of lipid, protein, and energy increase as the fish grows, accompanied by a decrease in water content Previous studies have found strong relationships between water content or dry mass content and other proximate compositions (Jonsson and Jonsson 1998, 2003; Pangle and Sutton 2005; Hartman and Margraf 2008). It is of interest to examine whether a common prediction model is possible for some closely related species
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