Validating fin tissue as a non-lethal proxy to liver and muscle tissue for stable isotope analysis of yellow perch (Perca flavescens)

Abstract

Stable isotope ecology typically involves sacrificing the animal to obtain tissues. However, with threatened species or in long-term longitudinal studies, non-lethal sampling techniques should be used. The objectives of this study were to (1) determine if caudal fin tissue could be used as a non-lethal proxy to liver and muscle for stable isotope analysis, and (2) assess the effects of ethanol preservation on δN and δC in fin tissue of juvenile yellow perch Perca flavescens. The δC of caudal fin was not significantly different from liver (t = -0.58; p = 0.57), and was more correlated with δN in liver (r = 0.78) than muscle (r = 0.56). Ethanol preservation enriched N andC for caudal fins, but by using our developed regression models, these changes in δN and δC can now be corrected. Overall, caudal fin tissue is a more reliable proxy to liver than muscle for δN and δC in yellow perch.

Season and species influence stable isotope ratios between lethally and non‐lethally sampled tissues in freshwater fish

“…This is likely due to differences in tissue chemical composition (Hayden et al, 2015) and isotopic turnover rates (Fry, 2006) between muscle and fins. This finding is consistent with other fish species (Fincel et al, 2012;Jardine et al, 2005) and with other populations of northern pike, yellow perch and lake whitefish (Hanisch et al, 2010;McCloskey et al, 2018;Winter et al, 2019). Species-isotope pairings with stable differences between tissues across seasons (no significant tissue-season interaction) were yellow perch δ 13 C (mean difference between muscle and caudal fin = 1.0‰, muscle and pectoral fin = 0.9‰), lake whitefish δ 13 C (mean difference between muscle and caudal fin = 2.6‰, muscle and pectoral fin = 1.9‰) and lake whitefish δ 15 N (mean difference between muscle and caudal fin = 0.4‰, muscle and pectoral fin = 0.3‰).…”

“…Tissues that can be sampled non-lethally, such as fins, scales and epidermal mucus, are alternatives to dorsal muscle for stable isotope analysis (Hette-Tronquart et al, 2012;McCloskey et al, 2018;Sanderson et al, 2009). These tissues have different chemical compositions and are formed through different metabolic processes than dorsal muscle, potentially resulting in different isotope ratios (DeNiro & Epstein, 1977;Macko et al, 1986).…”

Nonlethal Fin Sampling of North American Freshwater Fishes for Food Web Studies Using Stable Isotopes

“…For centrarchids, our Smallmouth Bass model ( = 0.99; = 0.99) showed better predictive capacity than a combined model built for Bluegill Lepomis macrochirus , Pumpkinseed Lepomis gibbosus , and Redbreast Sunfish Lepomis auritus from Massachusetts and New Brunswick ( = 0.97; ; Kelly et al 2006). Similarly, for percids, our models for Johnny Darter ( = 0.82; = 0.81) displayed a better predictive capacity than those developed for Walleye Sander vitreus in South Dakota ( = 0.92; = 0.80; Fincel et al 2012) or Yellow Perch Perca flavescens in Ontario ( = 0.80; = 0.56; McCloskey et al 2017). In addition, the interclass correlation coefficient—a measure of the proportion of the total variance in the response variable (muscle isotope values) that is accounted for by the groups (species)—was high for both mixed‐effects regression models (0.50 and 0.38 for δ 13 C and δ 15 N models, respectively).…”

“…Our results support the use of nonlethal fin tissue sampling in place of dorsal muscle for obtaining stable isotope ratios of North American freshwater fishes, thus reducing the future lethal take of individuals. To date, isotopic relationships between fin and muscle tissue for North American fishes have mostly focused on recreationally important species (Jardine et al 2005; Hanisch et al 2010; Curry et al 2014; McCloskey et al 2017). We build on this growing body of work by providing fin to muscle conversion models for 15 widely distributed North American fishes representing Catostomidae, Cyprinidae, Percidae, and Sciaenidae.…”

“…Once fin clips have been collected and analyzed for stable isotope values (Hayden et al 2015) and the resulting data have been corrected for lipid content (Kiljunen et al 2006; Logan et al 2008; Fagan et al 2011), it can be converted to muscle tissue values. We recommend using the species‐specific conversion models developed herein (see Table 2 for parameter estimates and uncertainty) and elsewhere for North American fishes (Jardine et al 2005; Kelly et al 2006; Sanderson et al 2009; Andvik et al 2010; Hanisch et al 2010; Fincel et al 2012; Curry et al 2014; McCloskey et al 2017). When species‐specific conversion models are not available, we recommend using our multispecies models.…”