Intra- and Interseasonal Changes in the Relative Condition and Proximate Body Composition of Broad Whitefish from the Prudhoe Bay Region of Alaska

Abstract

A relative weight approach was used to test the hypothesis that the condition of broad whitefish Coregonus nasus in the Prudhoe Bay region of Alaska increases during the summer feeding season in conjunction with their increasing lipid and protein contents and decreases during winter as fish consume these energy reserves. The conditions of individual fish collected across 12 summer dissection periods from 1988 to 1993 were indexed in terms of their residual values relative to a single whole‐population, least‐squares regression of loge(weight) against loge(length). Proximate body analyses of lipid and protein contents collected from individual fish across six dissection periods from 1991 to 1993 were also examined. Data pooled for individual year‐classes were used to test for increasing mean residual value, mean lipid content, and mean protein content during summer and for decreasing values of each during winter. Of the 68 cases examined (14 year‐classes over 6 years), mean residual value changed in the expected direction in 56 instances (P < 3.0 E–7). Of 24 cases in which seasonal changes in lipid and protein contents were available, lipid content changed in the expected direction in 23 instances (P < 3.0 E–6), and protein content changed in the expected direction in all 24 instances (P < 3.0 E–7). Mean residual value changed as expected in all 24 cases. The merits of relative condition‐relative weight in the study of fish ecology are discussed.

Reproduction, feeding and migration patterns of Prochilodus nigricans (Characiformes: Prochilodontidae) in northeastern Ecuador

“…To evaluate possible seasonal changes in condition, the LW relationships were compared using analysis of covariance (ANCOVA), where a relatively higher slope and/or intercept could indicate better condition. Residual analyses of the LW relationships were used as a complimentary approach to assessing the condition factor of individual fishes (e.g., Fechhelm et al, 1995). This latter condition factor assessment was done by plotting mean monthly (studentized) residuals against time and observing their positive and negative deviations from the average population predicted value.…”

“…Residual analysis as an index of condition factor for males, females and unsexed individuals of Prochilodus nigricans from the Aguarico River during 1999 (see Fechhelm et al, 1995). Shown are the monthly mean (shaded rectangles), ± standard error (vertical lines) and ± 95% confidence interval (open rectangles); sample sizes are above bars.…”

Length–weight and length–length relationships for three endemic cyprinidspecies of the Aegean region (Turkey) with proposed standard weight equations

“…the presence of nonnative species) (Giannetto et al, 2012b). The use of condition indices such as relative weight to evaluate the status of threatened rare or less-studied species is indeed strongly recommended (Didenko et al, 2004), since they are not invasive methods and do not require the sacrifice of the specimens (Fechhelm et al, 1995).…”

The condition conundrum: application of multiple condition indices to the dusky shark Carcharhinus obscurus

“…For each size class, 4 commonly used condition indices were calculated. HSI, the most widely used somatic measure (Stevenson & Woods 2006, Pope & Kruse 2007, was calculated using: HSI = [liver mass (kg) / total body mass (kg)] × 100 (1) The morphometric indices of condition assessed in the present study included CF (Ricker 1975, Nash et al 2006, Kn (Le Cren 1951) and residual morphometric condition, Rr PCL (Fechhelm et al 1995). CF was calculated using:…”

“…Given the large energetic demand on pregnant sharks during the gestation phase, pregnant and postpartum animals were isolated from the large female data set (≥210 cm PCL) and presented independently. The morphometric indices of condition assessed in the present study included CF (Ricker 1975, Nash et al 2006, Kn (Le Cren 1951) and residual morphometric condition, Rr PCL (Fechhelm et al 1995). CF was calculated using:…”