Temporal variation in δ 15N and δ 13C values from the offshore California Current System in sperm whale skin samples.

For mean calculations: Source-AAs are phenylalanine, glycine, lysine, tyrosine; Trophic-AA: glutamic acid, alanine, isoleucine, leucine, proline; Essential-AA: phenylalanine, valine, leucine. Isotopic shifts were calculated using the corresponding linear regression equations listed in this table. The annual decrease was calculated for shifts that exhibited a p-value≤0.05.Temporal variation in δ 15N and δ 13C values from the offshore California Current System in sperm whale skin samples.