Mercury in Seals from Eastern Canada

1973 ◽  
Vol 30 (6) ◽  
pp. 843-846 ◽  
Author(s):  
D. E. Sergeant ◽  
F. A. J. Armstrong
Keyword(s):  
Phoca Vitulina ◽  
Halichoerus Grypus ◽  
Eastern Canada ◽  
Small Pelagic Fish ◽  
Marine Food Web ◽  
Cystophora Cristata ◽  
Pagophilus Groenlandicus ◽  
Harbour Seals ◽  
Order Of Magnitude ◽  
Marine Food

Mercury concentrations in the tissues of four species of seals from individual localities in eastern Canada were highest in liver (usually 1–100 ppm) but up to 387 ppm and lowest in blubber (usually 0.1 ppm). Levels in muscle ranged from < 0.16 to 2.35 ppm. Values similar to those in muscle were found in the few specimens of heart, intestine, and lungs analyzed, and higher values in kidney and hair. Ratios of mercury in the liver to that in the muscle for adult seals were much greater than those found in two species of freshwater fish and three species of domestic animals exposed to wide ranges of mercury concentrations in their food. The ratios for seal pups, however, resembled those in the other animals.Mercury in seals increased with age and appeared to vary with the position in the marine food web of the organisms which they eat. Harp seals (Pagophilus groenlandicus), which feed on small pelagic fish and crustaceans, accumulated an order of magnitude less mercury than grey (Halichoerus grypus) and harbour (Phoca vitulina) seals, which live on large pelagic and benthic fish and cephalopods. However, grey and harbour seals are resident in eastern Canadian waters, which presumably contain higher mercury levels than arctic waters, where harp seals spend about half the year. Yet hood seals (Cystophora cristata), which spent more than half the year in arctic waters but feed on large fish and cephalopods, had mercury levels as high as grey and harbour seals.

Susceptibility of Grey (Halichoerus grypus) and Harp (Phoca groenlandica) Seals to the Influenza Virus and Mycoplasma of Epizootic Pneumonia of Harbor Seals (Phoca vitulina)

1984 ◽  
Vol 41 (1) ◽  
pp. 151-156 ◽  
Author(s):  
J. R. Geraci ◽  
D. j. St. Aubin ◽  
I. K. Barker ◽  
V. S. Hinshaw ◽  
R. G. Webster ◽  
...  
Keyword(s):  
Influenza Virus ◽  
New England ◽  
Influenza A ◽  
Phoca Vitulina ◽  
Lung Homogenate ◽  
Halichoerus Grypus ◽  
Harbor Seals ◽  
Eastern Canada ◽  
Cystophora Cristata ◽  
Phoca Groenlandica

Six grey, Halichoerus grypus, and 12 harp, Phoca groenlandica, seals were inoculated intratracheally with lung homogenate containing influenza virus A/seal/Mass/1/80 and mycoplasma from harbor seals, Phoca vitulina, which had died in an epizootic of pneumonia. The grey seals were refractory to infection, whereas some of the harp seals developed mild pneumonia. Virus was recovered from 4 of 10 harp seals necropsied, and antibodies were produced in 2 survivors. The mycoplasma given alone to 2 grey seals did not replicate or produce infection and was recovered from only 1 of 12 harp seals inoculated. We examined 99 grey, 102 harp, 14 harbor, and 7 hooded seals (Cystophora cristata) from eastern Canada and found antibodies to avian influenza A/seal/Mass/1/80 in 3 adult male grey seals from Sable Island, N.S.; this virus is apparently adaptable to other seal species. Related forms of the virus are highly suspect as the cause of past epizootics, and one is currently responsible for a new outbreak of pneumonia in New England harbor seals.

Host specificity and abundance of parasitic nematodes (Ascaridoidea) from the stomachs of five phocid species from Newfoundland and Labrador

1993 ◽  
Vol 71 (11) ◽  
pp. 2156-2166 ◽  
Author(s):  
John Brattey ◽  
Garry B. Stenson
Keyword(s):  
Newfoundland And Labrador ◽  
Phoca Vitulina ◽  
Halichoerus Grypus ◽  
Parasitic Nematodes ◽  
Fish Stocks ◽  
Cystophora Cristata ◽  
Pseudoterranova Decipiens ◽  
Large Numbers ◽  
Harbour Seals ◽  
Contracaecum Osculatum

Stomachs of 270 phocids from five species (bearded, Erignathus barbatus; hooded, Cystophora cristata; grey, Halichoerus grypus; harbour, Phoca vitulina; and ringed, P. hispida), collected off Newfoundland and Labrador during 1985–1993 were examined, and the numbers and percentages of larval and adult ascaridoid nematodes determined. Samples of adult nematodes were also identified using previously described allozymes. Bearded seals were infected mainly with Contracaecum osculatum A, C. osculatum B, and Pseudoterranova decipiens C, whereas hooded seals harboured mostly Phocascaris spp. Grey seals harboured large numbers of C. osculatum B, and small numbers of adult Anisakis simplex; harbour and grey seals were the only phocids heavily infected with P. decipiens B. Ringed seal stomachs contained fewer nematodes than other seal species and were mainly infected with C. osculatum B and Phocascaris spp. In several seal species positive, but no negative, associations in abundance were observed between nematodes. Sex ratios of adult nematodes among individual seals were heterogeneous, but changes in sex ratio suggest a bias towards female nematodes among larvae infecting fish and a selective loss of adult females during maturation. Overall, the results suggest that grey and harbour seals are the main source of larval sealworm (P. decipiens B) occurring in fish stocks off Newfoundland and Labrador, although small numbers of adult P. decipiens B also occurred in hooded seals.

Predation by Sharks on the Grey Seal (Halichoerus grypus) in Eastern Canada

1983 ◽  
Vol 40 (3) ◽  
pp. 267-271 ◽  
Author(s):  
Paul Brodie ◽  
Brian Beck
Keyword(s):  
Key Words ◽  
Population Size ◽  
Halichoerus Grypus ◽  
Longline Fishery ◽  
Grey Seal ◽  
Eastern Canada ◽  
The Past ◽  
Harbour Seals ◽  
Commercially Important ◽  
Important Fish

The increase in population size of the grey seal (Halichoerus grypus) off eastern Canada over the past 20 yr may be attributed to a decrease in shark stocks, their supposed predators. Reduction of the shark population is presumed to have resulted from a directed longline fishery and, of greater significance, from a change in the fishery for swordfish (Xiphias gladius) from selective harpooning to pelagic longlining, which has produced a large bycatch of sharks. The resulting enhanced survival of grey seals is reflected in greater infestation of commercially important fish species by the codworm (Phocanema decipiens).Key words: grey seals, harbour seals, sharks, swordfish, codworm, predation, fisheries

scholarly journals Trophic niche overlap between sympatric harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) at their Southern European limit range (Eastern English Channel)

2020 ◽  
Author(s):  
Yann Planque ◽  
Jérôme Spitz ◽  
Matthieu Authier ◽  
Cécile Vincent ◽  
Florence Caurant
Keyword(s):  
Niche Overlap ◽  
Phoca Vitulina ◽  
Trophic Niche ◽  
Halichoerus Grypus ◽  
English Channel ◽  
Harbour Seals

Fatal Interspecies Mating Attempts of a Grey Seal (Halichoerus grypus) with Harbour Seals (Phoca vitulina) on the German North Sea Coast

2020 ◽  
Vol 174 ◽  
pp. 166
Author(s):  
K. Hülskötter ◽  
S. Rohner ◽  
S. Groß ◽  
J. Lakemeyer ◽  
M. Fähndrich ◽  
...  
Keyword(s):  
North Sea ◽  
Phoca Vitulina ◽  
Halichoerus Grypus ◽  
Grey Seal ◽  
Harbour Seals ◽  
Sea Coast ◽  
North Sea Coast

scholarly journals Trophic niche overlap between sympatric harbour seals ( Phoca vitulina ) and grey seals ( Halichoerus grypus ) at the southern limit of their European range (Eastern English Channel)

2021 ◽  
Author(s):  
Yann Planque ◽  
Jérôme Spitz ◽  
Matthieu Authier ◽  
Gaël Guillou ◽  
Cécile Vincent ◽  
...  
Keyword(s):  
Niche Overlap ◽  
Phoca Vitulina ◽  
Trophic Niche ◽  
Halichoerus Grypus ◽  
English Channel ◽  
Southern Limit ◽  
Harbour Seals

scholarly journals Observations on seals on the island of Surtsey in the period 1980-2012

2015 ◽  
Vol 13 ◽  
pp. 41-43
Author(s):  
Erlingur Hauksson
Keyword(s):  
Breeding Site ◽  
Phoca Vitulina ◽  
The Other ◽  
South Coast ◽  
Harbour Seal ◽  
Halichoerus Grypus ◽  
Grey Seal ◽  
The South ◽  
Breeding Sites ◽  
Harbour Seals

Grey seals (Halichoerus grypus Fabricius) and harbour seals (Phoca vitulina L.) have been surveyed on the coasts of Iceland since 1980. During the period 1980-2012, both seal species have declined markedly in numbers at the Icelandic coast. The grey seal has established a considerable breeding site on the northern spit of the Surtsey island. This is at present one of the biggest grey seal rookeries on the southern shores of Iceland, with estimated about 60 pups born there in the autumn of 2012. On the other hand, the harbour seal has not been numerous on Surtsey during breeding time in the summer. Breeding sites of harbour seals on the south coast of Iceland closest to Surtsey are in the estuaries of the glacial rivers Ölfusá, Þjórsá, Markarfljót and Kúðafljót. Harbour seals, however, haul-out in great numbers on the northern shores of Surtsey during the winter, presumably using the island as a resting place after foraging in the adjacent waters.

Lungworm (Nematoda: Metastrongyloidea) infections in Canadian phocids

1998 ◽  
Vol 55 (4) ◽  
pp. 825-834 ◽  
Author(s):  
Jean-François Gosselin ◽  
Lena N Measures ◽  
Jean Huot
Keyword(s):  
Detrimental Effect ◽  
Halichoerus Grypus ◽  
Bearded Seal ◽  
Eastern Canada ◽  
New Host ◽  
Ringed Seals ◽  
Phoca Groenlandica ◽  
Harbour Seals ◽  
Young Of The Year ◽  
Otostrongylus Circumlitus

Otostrongylus circumlitus (Railliet, 1899) was found in 5% (16/308) of grey seals (Halichoerus grypus), 6% (1/17; intensity = 38) of harbour seals (Phoca vitulina), and none of 100 harp seals (Phoca groenlandica) from eastern Canada and none of 31 ringed seals (Phoca hispida) from Holman, Northwest Territories. Eighty-two percent of these infections were observed in young-of-the-year seals. Filaroides (Parafilaroides) gymnurus (Railliet, 1899), detected in nodules in the superficial parenchyma of the lungs, infected 24% (5/16) of grey seals, 27% (4/15) of harbour seals, 57% (29/51) of harp seals, 81% (25/31) of ringed seals, and one stranded bearded seal (Erignathus barbatus) (new host report for harp, ringed, and bearded seals; new locality report for Holman). Filaroides (Parafilaroides) hispidus Kennedy, 1986 was found in systematically sliced lungs of grey seals (2/3; new host report) and ringed seals (2/7) but not in harp seals (n = 11) or harbour seals (n = 5). Intensity ranged from 37 to 3570 for F. (P.) gymnurus and from 295 to 1196 for F. (P.) hispidus. No detrimental effect on body condition of seals could be associated with infection by lungworms.

Abundance and maturity of three species of parasitic anisakine nematodes (Pseudoterranova decipiens, Contracaecum osculatum, Anisakis simplex) occurring in Sable Island harbour seals (Phoca vitulina)

2002 ◽  
Vol 80 (3) ◽  
pp. 442-449 ◽  
Author(s):  
Wayne T Stobo ◽  
L Paul Fanning ◽  
Brian Beck ◽  
G Mark Fowler
Keyword(s):  
Prey Species ◽  
Phoca Vitulina ◽  
Final Host ◽  
Anisakis Simplex ◽  
Halichoerus Grypus ◽  
Commercial Fish ◽  
Pseudoterranova Decipiens ◽  
Harbour Seals ◽  
Seal Population ◽  
Contracaecum Osculatum

Three species of anisakine nematodes (Pseudoterranova decipiens, Contracaecum osculatum, Anisakis simplex) co-occur in the stomachs of Sable Island harbour seals (Phoca vitulina). The sealworm, P. decipiens, was the commonest nematode in these seals. Anisakis simplex was found in much smaller numbers, none mature, indicating that the harbour seal is not a true final host to this parasite. Contracaecum osculatum was rare but half were mature. Pseudoterranova decipiens increased in abundance with size of the seal. An inverse relationship was observed between P. decipiens abundance and the age of seals of similar size, probably owing to changes in diet. Numbers of P. decipiens may have declined over the summer, coincident with an increase in the proportion of mature worms in the stomach. From similarities between the worm infections of grey seals (Halichoerus grypus) and harbour seals, we infer that A. simplex abundance may also exhibit a decline in abundance. Contracaecum osculatum was only encountered during the latter half of the year, suggesting an association with prey species of corresponding periodicity in their distribution. We estimate that the abundance of sealworm in harbour seals is about 2.5% of that carried by the grey seal population. This could imply that harbour seals represent an insignificant vector of the sealworm infecting commercial fish species in the Northwest Atlantic, provided density-dependent relationships exist between worm abundances in different host species.

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