210Po, Cd and Pb distribution and biomagnification in the yellowfin tuna Thunnus albacares and skipjack tuna Katsuwonus pelamis from the Eastern Pacific

- Mean 210Po activity (Bq kg−1) in liver was 119 in K. pelamis and 157 in T. albacares.
- Trophic position of T. albacares (4.60) was higher than K. pelamis (3.94).
- Pb was biomagnified between stomach content and muscle of T. albacares.

We measured Cd and Pb in the muscle and stomach contents of Thunnus albacares and Katsuwonus pelamis to define the distribution of the elements in the tissues and their degrees of biomagnification. 210Po was measured in the livers of both species and compared to the results of similar studies. The trophic position of the tuna species was determined by N isotope measurements. The average activity of 210Po in the liver ranged from 119 to 157 (Bq kg−1 wet weight) in K. pelamis and T. albacares. The trophic position of T. albacares (4.60) was higher than that of K. pelamis (3.94). The Cd content of the muscle increased significantly with the trophic position of the tuna. δ13C in T. albacares and K. pelamis varied, with values of 3.13 and 1.88‰, respectively. The δ15N values in yellowfin tuna were higher than in skipjack tuna. The trophic position of T. albacares (4.60 ± 0.67) was therefore more elevated than that of K. pelamis (3.94 ± 1.06). Pb was biomagnified in T. albacares (transfer factor = 1.46).