Relationships Between Body Condition Indices and Proximate Composition in Adult Walleyes

Abstract

Relationships between indices of condition and measures of proximate body composition were examined among and within nine populations of mature walleyes Sander vitreus that varied widely in growth rate and lipid status. Body condition, measured as the residuals from mass versus length regressions, was negatively related to mean water content and positively related to mean lipid content among populations. When the roles of water and lipid content were examined simultaneously within populations, most of the variance in condition was accounted for by lipid content. The strength of the relationships between various condition indices and body proximate composition varied considerably among populations but less between sexes within populations. Furthermore, the strength and nature of these relationships was not strongly influenced by the choice of mass-at-length index (residuals, relative condition, relative weight, or Fulton's K). The visceral-somatic index and muscle lipid content both exhibited slightly stronger relationships with body proximate composition than did mass-at-length condition indices for both sexes. The hepatosomatic index was more consistently related to somatic lipid content for females than for males in most populations. Relatively simple condition indices can provide reliable surrogates of body proximate composition in many adult walleye populations, but caution should be exercised in extrapolating from condition-composition relationships among populations.

Behavior as biomarker? Laboratory versus field movement in round goby (Neogobius melanostomus) from highly contaminated habitats

“…Round goby collected from contaminated areas often have demonstrated ventral fin damage or erosion ; this study), but fish with eroded fins did not explore or disperse differently in a novel environment than fish with normal fins. Round goby from sites of low and high contamination were in similar body condition; condition reflects body composition and energetic levels (Kaufman et al 2007) and can be used as a contaminant biomarker (Schlenk et al 2008). Other physiological mechanisms, such as neurotoxic effects, chronic stress, or endocrine disruption may have been the proximate cause of the reduced activity here observed here, but these factors have yet to be explored in detail in this system.…”

Abundance, growth, and life history characteristics of sympatric walleye (Sander vitreus) and sauger (Sander canadensis) in Lake Winnipeg, Manitoba

“…Where autocorrelation was significant, the appropriate autoregressive terms were included in the models prior to testing for temporal trends. Morphometric body condition was estimated for each fish as the residual from a log e mass vs. log e FL relationship (Kaufman et al, 2007) fitted to the full data set (both species, both sexes, and all regions and years combined). For the analyses of growth rate and age and size of maturation, we pooled data into five 5-year intervals (1979-1983, 1984-1988, 1989-1993, 1994-1998, and 1999-2003, each inclusive) to improve sample sizes.…”

Reproductive allocation in exploited lake whitefish (Coregonus clupeaformis) and walleye (Sander vitreus) populations

“…Changes in food availability due to changes in population abundance, ecosystem productivity, or prey community composition are often accompanied by a response in growth rates or energetic status for many fish species, including both lake whitefish (Healey, 1980;Mills, 1985;Pothoven et al, 2001;Lumb et al, 2007;Hoyle et al, 2008;Rennie et al, 2009) and walleye (Chevalier, 1977;Jones et al, 1994;Craig et al, 1995;Colby and Baccante, 1996). In the current study, we used somatic lipid content as an index of energy storage, a variable that correlates well with morphometric condition in both species (Kaufman et al, 2007;Rennie and Verdon, 2008). We found that lake whitefish grew more slowly than walleye, but also increased in lipid concentration with age, whereas walleye grew faster but declined in lipid concentration with age, particularly for females.…”

“…The methods used for fish processing and tissue analyses have been described in detail previously for walleye (Kaufman et al, 2007;Moles et al, 2008), and an identical protocol was used for lake whitefish. Briefly, each individual was measured from the tip of the snout to the fork of the caudal fin (fork length (FL), ±1 mm), then weighed with (total mass, ±10 g wet) and without gonads (somatic mass, ±10 g wet).…”

“…All freeze-dried tissues were ground to a coarse powder in a ball mill. Total lipids were then extracted from the ground tissues using a chloroform:methanol procedure as outlined previously (Kaufman et al, 2007;Moles et al, 2008) and expressed on a dry mass basis. Somatic and whole body lipid concentrations were reconstructed from masses, and moisture and lipid concentrations of the component tissue samples.…”