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<sup>13</sup>C and <sup>15</sup>N analysis in muscle and liver of wild and reared young-of-the-year (YOY) Atlantic bluefin tuna

Abstract:

Stable isotope analysis (SIA) has become a useful tool in trophic ecology research, but experimental studies are essential for their correct application in field studies. Young-of-the-year (YOY) Atlantic bluefin tuna (ABFT) caught in the Mediterranean Spanish coast were reared on a common natural prey to determine prey-muscle and prey-liver discrimination factors. Significantly increased isotopic values were found in lipid-extracted tuna samples of muscle and liver versus bulk samples, while C:N values decreased following lipid extraction. Such isotopic differences were paralleled by differences in the discrimination factors estimated for δ 13C (δ 13C) in muscle and liver, though δ 15N was apparently unaffected by lipid removal. Isotopic differences were observed between muscle and liver for wild ABFT, which was probably due to different turnover rates. The δ 13C estimates obtained from lipid-extracted samples of muscle and liver were 0.32±0.04 and 0.39±0.23, respectively. δ 15N values estimated from bulk samples were 1.46±0.06 for muscle and 1.62±0.22 for liver. © 2012 Elsevier B.V.