Table 3.

Carbon and nitrogen stable isotope ratio values (δ¹³C and δ¹⁵N, ‰) and carbon to nitrogen ratios (C:N) for four tissue types (whisker, red blood cells (RBC), serum, and plasma) analyzed from the captive pinnipeds listed in Table 1. Whisker samples are the average of the three most recently grown segments. Isotope values are reported as mean ± SD for sample sizes >1. Sample sizes are provided in Table 1.

	Whisker			RBC			Plasma			Serum
Species	δ13C	δ15N	C:N	δ13C	δ15N	C:N	δ13C	δ15N	C:N	δ13C	δ15N	C:N
Monk seal	−17.5 ± 0.04	14.5 ± 0.01	2.9	−19.1	14.2	3.3	−19.3	15.0	3.7	---	---	---
Elephant seal	−16.5b	14.4b	2.9	---	---	---	−18.3	15.5	3.7	−18.5	15.7	3.6
Bearded seal	−16.6 ± 0.13	15.4 ± 0.07	2.8 ± 0.07	---	---	---	---	---	---	−18.6	16.6	3.9
Ringed seal #1	−16.2 ± 0.04	14.8 ± 0.04	2.9	−18.3	14.4	3.2	−18.8	15.8	3.7	---	---	---
Ringed seal #2	−16.2 ± 0.06	14.6 ± 0.09	2.9	---	---	---	---	---	---	---	---	---
Spotted seal #1	−16.2 ± 0.04	15.6 ± 0.02	2.9	−18.3	14.4	3.3	−18.8	15.7	3.7	---	---	---
Spotted seal #2	−16.3 ± 0.06	15.7 ± 0.06	2.9	−18.3	14.9	3.2	−18.5	15.8	3.7	---	---	---
Harbor seal	−16.3 ± 0.04	15.3 ± 0.07	2.9	−18.2	14.2	3.3	−18.7	15.5	3.8	---	---	---
California sea liona	---	---	---	−17.9	15.2	3.3	−18.3	16.3	3.8	−18.5	16.4	3.9

^aSerum samples were collected twice, approximately one year apart and used to calculate an average trophic discrimination factor. Here we present the isotope ratio values for the sample that was obtained at the same time as the plasma and RBCs from this animal

^bOnly one whisker segment was analyzed for the elephant seal, whereas three consecutive segments were analyzed and the results then averaged for all other animals