An assessment of morphometric indices, blood chemistry variables and an energy meter as indicators of the whole body lipid content in Micropterus dolomieu, Sander vitreus and Ictalurus punctatus

Abstract

The effectiveness of several non-lethal techniques as indicators of total lipid content in smallmouth bass Micropterus dolomieu, walleye Sander vitreus and channel catfish Ictalurus punctatus was investigated. The techniques included (1) the Fulton and relative condition factors, (2) relative mass, (3) plasma indicators of nutritional status (alkaline phosphatase, calcium, cholesterol, protein, triglycerides and glucose) and (4) readings from a hand-held, microwave energy meter. Although simple linear regression analysis showed that lipid content was significantly correlated with several predictor variables in each species, the r values for the relations ranged from 0·17 to 0·50 and no single approach was consistent for all species. Only one model, between energy-meter readings and lipid content in I. punctatus, had an r value (0·83) high enough to justify using it as a predictive tool. Results indicate that no single variable was an accurate and reliable indicator of whole body lipid content in these fishes, except the energy meter for I. punctatus.

Variation of body condition and plasma energy substrates with life stage, sex, and season in wild‐sampled nurse sharks Ginglymostoma cirratum

“…Accordingly, the positive relationship found here between body condition and KB ratio in immature G. cirratum may suggest that body condition, measured via span condition analysis, is a good indicator of energetic state during this life stage. The lack of such a relationship in mature G. cirratum may imply that morphological body condition parameters may only reflect an organism's energy reserves during certain life stages or reproductive states (Hammerschlag et al, 2018;Hussey et al, 2009;Mesa & Rose, 2015;Naesje et al, 2006;Sardenne et al, 2016). Future research should continue to explore plasma KB ratio as an indicator of energetic state in elasmobranchs and its relationships with other parameters related to elasmobranch condition (e.g., HSI).…”

Energy content of anchovy and sardine using surrogate calorimetry methods

“…Numerous studies described a positive correlation between fatmeter and lipid content or morphometric condition indices (Bayse et al, 2018;Brosset et al, 2015a;Davidson and Marshall, 2010;Másílko et al, 2016). Furthermore the accuracy of fatmeter as a surrogate of direct techniques to estimate energy reserves has been assessed for several species (Bayse et al, 2018;Goñi and Arrizabalaga, 2010;Mann et al, 2009;Mesa and Rose, 2015;Schloesser and Fabrizio, 2017). As for the sardine and anchovy, the use of Distell Fish Fatmeter has been validated as a good indirect method to estimate lipid content (Brosset et al, 2015a), but whether it could also provide accurate estimates of energy content has not been investigated.…”

Condition Indices as Surrogates of Energy Density and Lipid Content in Juveniles of Three Fish Species

“…The fatmeter measures the water content of the tissues beneath the skin, which relates to the amount of lipid stored in subdermal reserves and associated peripheral muscle tissues (hereafter, subdermal lipids). For many species, measures of subdermal lipid content from the fatmeter are well correlated with wholefish or fillet lipid content measured by proximate composition analysis (0.58 ≤ r 2 ≤ 0.87; Vogt et al 2002;Hendry and Beall 2004;Bransden et al 2007;Kaga et al 2009;Saillant et al 2009;Van Sang et al 2009;Caldwell et al 2013;Mesa and Rose 2015), but these relationships have often been developed for adult fish only, and the species investigated thus far are those that are likely to accumulate large lipid stores as adults.…”