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The North Atlantic fin whale was subject to heavy exploitation in the past and, despite partial recovery, it is still considered endangered. Recent research has questioned its currently accepted subpopulation structure and migratory movements, challenging management and conservation efforts. Here we contribute to this discussion by presenting results of stable isotope analysis of fin whale bones and krill samples collected from fin whale stomachs from two exploited areas, west Iceland and northwest Spain, and comparing these results with North Atlantic isoscapes. In krill, δ15N values were highly variable and no significant differences in δ15N and δ13C between areas emerged. δ15N and δ13C values in bone were higher than in krill, due to trophic enrichment, and were not significantly different between areas. Both krill and bone results were slightly inconsistent with the local isoscapes, maybe due to seasonal variations in local productivity and in krill diet and, in the case of bone, to its capability to integrate long-term isotopic values, derived from food consumed in distant areas. Conversely, δ18O values, which reflect the basal signal of sea water, were consistent with isoscapes and significantly higher in whales from northwestern Spain, possibly indicating migration to breeding grounds located at lower latitudes. [ABSTRACT FROM AUTHOR]

In this study we aim to assess the daily ingestion rates of synthetic particles by the fin whales (Balaenoptera physalus) that feed off the western coast of Iceland. To do so, we collected and analysed samples from the stomach content of 25 fin whales, consisting solely of northern krill (Meganyctiphanes norvegica). The particles found consisted of fibres and fragments, mainly blue, black and red, with an average size of 1.2 ± 1.3 mm. To confirm the synthetic nature of these particles, we used Micro-Fourier Transform Infrared Spectroscopy and comparison with a polymer library. The mean concentration of synthetic particles in the krill samples found in the stomachs of whales was 0.057 particles per gram, a value much lower than that previously reported for particle uptake by krill. From this concentration in krill, we estimated that the daily intake of synthetic particles for the North Atlantic fin whale would be ranging from 38,646 ± 43,392 to 77,292 ± 86,784 particles per day. Although at this level it is not possible to assess the impact of synthetic particles and their associated chemicals on the North Atlantic fin whale population, concentrations of these contaminants are likely to increase in the future, potentially causing adverse effects on whales and other marine mammals. [Display omitted] • Stomach content samples from 25 whales from western Iceland were analysed. • The only ingested prey found in the samples was northern krill. • The average concentration in krill was 0.057 synthetic particles (SP) per gram. • The number of SP daily ingested by fin whales was estimated in the tens of thousands. • SP presence in their diet might facilitate the exposure of whale populations to POPs. [ABSTRACT FROM AUTHOR]

Pollution of the marine environment by litter composed of plastics is a growing concern. Chemical additives such as organophosphate flame retardants (OPFRs), which are added to plastics to improve their qualities, are in focus because they allegedly cause adverse effects on marine fauna. Here we analyse OPFR levels in the muscle of fin whales because, as a mysticete, this cetacean obtains its food by filter-feeding and is thus highly vulnerable to marine litter. Moreover, the fin whale performs long-range migrations from low-latitude areas in winter to high-latitude areas in summer, a trait that makes it a potentially good large-scale biomonitor of pollution. We also analyse OPFR levels in its main prey, the krill Meganyctiphanes norvegica , to assess transfer through diet. The samples analysed consisted of muscle tissue from 20 fin whales and whole-body homogenates of 10 krill samples, all collected off West Iceland. From the 19 OPFRs analysed, we detected 7 in the fin whale and 5 in the krill samples. Tri-n-butyl phosphate (TNBP), Isopropylated triphenyl phosphate (IPPP) and Triphenylphosphine oxide (TPPO) were the most abundant compounds found in both species. Mean ∑OPFR concentration, expressed on a lipid weight basis, was 985 (SD = 2239) ng g−1 in fin whale muscle, and 949 (SD = 1090) ng g−1 in krill homogenates. These results constitute the first evidence of the presence of OPFRs in the tissues of fin whales. Furthermore, they seem to support the non-significance of bioaccumulation of OPFRs through lifespan and of biomagnification trough the food web. Unlabelled Image • We provide the first evidence of OPFR presence in the tissues of fin whales. • OPFRs were detected in the fin whale main prey, the krill Meganyctiphanes norvegica. • TNBP, IPPP and TPPO are the most abundant OPFRs in both fin whales and krill. • OPFRs do not seem to bioaccumulate or biomagnify. [ABSTRACT FROM AUTHOR]