Fatty acid signature data of potential yellow-billed loon prey in the Arctic coastal plain of Alaska, 2009-2011.

Prey samples were allowed to partially thaw and then homogenized using a Kinematica GmbH tissue homogenizer for fish less than 250 mm fork length and a blender for larger fish. When prey mass was less than 1 g, prey of the same species from the same lake were homogenized together to form composite samples. Approximately 1 g of homogenized prey tissue was subsampled and stored in a glass vial with 4.5 mL of chloroform at -80 degrees C for analysis. Fatty acid methyl esters were prepared using acidic transesterification. Thin-layer chromatography indicated the presence of fatty alcohols in diet items resulting from the transesterification of wax esters. Wax ester alcohols were converted to their respective fatty acids to account for wax esters in diets. Fatty acid methyl esters were quantified using temperature-programmed gas liquid chromatography on a Varian Autosystem II Capillary FID gas chromatograph fitted with a 30 m by 0.25 mm (in diameter) column coated with 50% cyanopropylmethylpolysiloxane (DB-23) and linked to a computerized integration system (Varian Galaxie software). Each chromatogram was manually assessed for correct peak identification and integration of peak areas.