Four halogenated dimethyl bipyrroles (HDBPs), hypothesized to be naturally produced, were quantitated in marine mammal blubber from a number of species obtained from various locations worldwide. HDBPs were found in samples from all locations studied. Concentrations of total HDBPs (SigmaHDBPs) ranged from 0.4 ng/g lipid weight in ringed seals (Phoca hispida) from the White Sea to 2,540 ng/g lipid weight in Dall's porpoise (Phocoenoides dalli) from the northwestern North Pacific Ocean. At their highest levels, SigmaHDBPs made up 11% of the total quantitated organohalogen body burden of adult male Dall's porpoises. In two beluga (Delphinapterus leucas) data subsets, it was found that males contained significantly higher concentrations of SigmaHDBPs than females. No significant effects of age or sex on SigmaHDBPs were observed in harbor seal (Phoca vitulina) and bowhead whale (Balaena mysticetus) data subsets. The geographical distribution of concentrations did not resemble that of the ubiquitous anthropogenic organohalogen, polychlorinated biphenyl congener CB-153. Higher concentrations of HDBPs and different patterns of congeners were observed in samples from Pacific as opposed to non-Pacific Ocean influenced environments. Concentrations of HDBPs in beluga from the Arctic and St. Lawrence River were similar. Their high abundance in north Pacific Ocean biota and widespread occurrence suggest that HDBPs undergo extensive transport from a source located primarily in the Pacific Ocean. Evidence from HDBP congener patterns indicates that both ocean currents and atmospheric transport likely play a role in the movement of HDBPs. These results imply that HDBPs and anthropogenic organohalogens have different sources and support the natural production hypothesis.

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Interspecific competition is an important structuring element in marine ecosystems, especially in the Southern Ocean which offers few prey choices to comparatively large predator populations. We present the first simultaneous observations of at-sea behaviour and attendance patterns of 3 synchronously breeding, central place, krill foragers at Bouvetøya -a small, isolated, sub-Antarctic island in the South Atlantic. Time depth recorders and satellite transmitters were deployed during the austral summer of 2007/2008 on 47 lactating Antarctic fur seals Arcto-cephalus gazella (AFS) rearing pups and on 20 macaroni Eudyptes chrysolophus (MAC) and 30 chinstrap Pygoscelis antarctica penguins (CHIN) rearing chicks. All 3 species showed a strong preference for the west side of the island, and their foraging ranges overlapped markedly. Solar elevation influenced the timing of departures from, and arrivals to, the island with markedly different patterns between the seals and the penguins. Diving patterns also showed significant differences among the 3 species, with the frequency of diving being higher at night for the AFS, while both penguin species dove more frequently during the day. But a common, vertical diel pattern occurred in all 3 species, with shallow diving occurring at night and deep diving during the day, consistent with the vertical migration of krill. MACs targeted 2 depth layers for feeding, including a deep prey layer at ~70 m, which was not exploited by AFSs and CHINs. The results suggest that there is potential for competitive overlap among these 3 krill predators at Bouvetøya, but that it is reduced via both spatial (horizontal and vertical) and temporal partitioning of foraging areas.

This study reports fatty acid profiles and vitamin A and vitamin E contents of the milk of the harp seal (Phoca groenlandica) and hooded seal (Cystophora cristata) throughout the lactation period, as well as standard compositional analyses. The milk for this study was collected from harp and hooded seals breeding on the pack ice in the Gulf of St. Lawrence. Mother-pup pairs were serially captured, or point-sampled, in order to obtain milk samples during different lactation stages. Milk lipids showed the respective species' typical patterns during lactation, with a significant increase for harp seal milk and a relatively constant value for hooded seal milk. The profiles of most of the milk fatty acids remained relatively stable over the course of lactation in both species. Vitamin A content was also quite stable through lactation. By contrast, vitamin E content underwent a dramatic drop between the day of birth and early lactation for harp seals and from birth to midlactation for hooded seals. It then continued to decrease at a slower rate until the end of lactation in both species. The highest vitamin E content of colostrum reached 125 mg/kg of milk for harp seals and 200 mg/kg of milk for hooded seals. These concentrations subsequently dropped to 20-50 mg/kg of milk by early or mid lactation. These changes in this lipophilic, antioxidizing vitamin were not correlated with milk lipid content or its polyunsaturated fatty acid profiles.Résumé : Cette étude traite de l'évolution du profil en acides gras ainsi que des teneurs en vitamine A et en vitamine E dans le lait de Phoque du Groenland (Phoca groenlandica) et de Phoque à capuchon (Cystophora cristata) au cours de la lactation. La composition grossière du lait est également présentée. Les échantillons de lait ont été recueillis sur des Phoques du Groenland et des Phoques à capuchon qui se reproduisent sur la banquise du golfe du Saint Laurent. Dans le but d'avoir des échantillons de lait à différents stades de lactation, les couples mères-petits ont fait l'objet de captures successives ou ponctuelles. Les concentrations en lipides du lait suivent l'évolution habituellement observée pour ces espèces, avec une augmentation considérable dans le lait de Phoque du Groenland et une teneur relativement constante dans le lait de Phoque à capuchon. Chez les deux espèces, le profil de la plupart des acides gras du lait reste assez stable au cours de la lactation. De même, le contenu en vitamine A est relativement stable pendant toute la période de la lactation. Par contre, la concentration en vitamine E du lait subit une chute spectaculaire entre le jour de la naissance et le premier tiers de la lactation chez les Phoques du Groenland et entre le jour de la naissance et le milieu de la lactation chez les Phoques à capuchon. Elle continue ensuite à diminuer à un taux plus lent jusqu'à la fin de la lactation. Les contenus en vitamine E du colostrum atteignent 125 mg/kg de lait chez le Phoque du Groenland et 200 mg/kg de lait chez le Phoque à capuchon. Les concent...

Identifying foraging areas of individuals and correlating them with potential food resources allows for a better understanding of predator-prey relationships. Herein, we examine whether grey seal movements were associated with overwintering concentrations of several commercial fish species in the Cabot Strait, Atlantic Canada, using data from satellite transmitters deployed on grey seals (between 1993 and 2005) and winter bottom-trawl survey data (1994 to 1997). The distribution of searching effort by male grey seals varied throughout the winter. In early winter, males concentrated their movements around St. Paul's Island. In late winter, they were found to the southeast of this area, where females also occurred. The fish community differed between apparent foraging and non-foraging areas. Densities of small plaice, hake and redfish, large herring and cod of all sizes were relatively high in the male grey seal foraging zones; female foraging zones were characterized by higher densities of small plaice and redfish and large cod. Areas where grey seal foraging was not concentrated were characterized by high densities of medium and large redfish as well as large turbot and witch flounder. Diet samples are needed to determine whether grey seals are feeding on the fish groups that distinguish foraging from nonforaging areas or alternatively on other prey that occur in the same areas.KEY WORDS: Marine predator · Foraging areas · Cod · Spatial overlap · First-passage time · Groundfish · Gulf of St. Lawrence Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 462: [273][274][275][276][277][278][279][280][281][282][283][284][285][286] 2012 spond to annual losses of < 5% of adult cod to fishing and ~45% to natural mortality. It has been suggested that predation by an increasing grey seal population (Thomas et al. 2008) may be an important factor in the elevated natural mortality of adult cod (Chouinard et al. 2005, Benoît & Swain 2008, Swain et al. 2009). However, diet studies from the southern Gulf have not supported the hypothesis that seals are consuming large numbers of large cod (e.g. Hammill et al. 2007). But these studies, which are based on prey hard parts (in particular otoliths or ear bones) found in the digestive tracts of seals, may underestimate the consumption of large fish if their heads are not consumed (Hauser et al. 2008, Phillips & Harvey 2009 or if sampling has not occurred where grey seals and large fish overlap (Benoît et al. 2011).The overwintering period, when southern Gulf cod occur in dense aggregations at consistent locations (see 'Results'), is a period when cod may be an attractive prey resource to grey seals. However, sampling of seals for diet studies at this time of year is logistically challenging. In theory, the availability and distribution of resources is expected to affect the distribution of animals as well as their space-use strategy (Johnson 1980, Manly et al. 2002, and effective predators should concentrate effort in areas ...