Development of non-lethal sampling of carbon and nitrogen stable isotope ratios in salmonids: effects of lipid and inorganic components of fins |
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Authors: | Conor T. Graham Simon S.C. Harrison Chris Harrod |
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Affiliation: | 1. Enterprise Centre, School of Biological, Earth and Environmental Sciences, University College Cork, North Mall, Cork, Irelandgrahamconor@gmail.com;3. Enterprise Centre, School of Biological, Earth and Environmental Sciences, University College Cork, North Mall, Cork, Ireland;4. Medical Biology Centre, School of Biological Sciences, Queen's University Belfast, Belfast, UK;5. Instituto de Investigaciones Oceanológicas, Universidad de Antofagasta, Antofagasta, Chile |
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Abstract: | The preferred tissue for analyses of fish stable isotope ratios for most researchers is muscle, the sampling of which typically requires the specimen to be sacrificed. The use of non-destructive methods in fish isotopic research has been increasing recently, but as yet is not a standard procedure. Previous studies have reported varying levels of success regarding the utility of non-lethally obtained stable isotope materials, e.g. fins, but none have accounted for the potential compounding effects of inorganic components of fin rays or lipids. Comparisons of carbon (δ13C) and nitrogen (δ15N) stable isotope ratios of muscle with adipose and caudal fin of two salmonids, Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta L.), revealed that caudal fin can be used as a non-destructive surrogate for muscle in stable isotope analysis, but that adipose fin, where available, is a better proxy. The use of a published model to inexpensively counteract the confounding effect of lipids, which are depleted in 13C, greatly improved the relationship between fish muscle and fins. However, efforts to account for the inorganic components of fin rays were counterproductive and required twice the biomass of fins clipped from each fish. As this experiment was conducted on wild fish, controlled laboratory studies are required to confirm these field observations. |
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Keywords: | carbon-13 decalcification fins fish isotope ecology lipids methodology muscles nitrogen-15 sampling techniques |
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