Incidence of the Ascarid Porrocaecum decipiens in the Stomachs of Three Species of Seals along the Southern Canadian Atlantic Mainland

1958 ◽  
Vol 15 (4) ◽  
pp. 495-516 ◽  
Author(s):  
D. M. Scott ◽  
H. D. Fisher
Keyword(s):  
East Coast ◽  
Atlantic Cod ◽  
Atlantic Coast ◽  
Phoca Vitulina ◽  
The Other ◽  
Harp Seal ◽  
Harbour Seal ◽  
Halichoerus Grypus ◽  
Bay Of Fundy ◽  
Harbour Seals

Identifications were made of ascarids collected from 1948 to 1956 from the stomachs of 318 harbour seals (Phoca vitulina), 812 harp seals (P. groenlandica), and 127 grey seals (Halichoerus grypus) killed in several localities along the Atlantic coast of Canada. Porrocaecum and 2 other genera of ascarids, tentatively identified as Anisakis and Contracaecum, were present in each species of seal. All 112 male Porrocaecum that were identified to species were P. decipiens.Almost all stomachs of harbour and grey seals at all seasons and in all localities contained P. decipiens. Considering all localities, the overall average incidence was about 20 adult P. decipiens in harbour seals and about 100 in grey seals.P. decipiens was normally much rarer in the stomachs of harp seals than in the other seals. It appeared most frequently in harp seals taken around the Magdalen Islands in April and May. The incidence of adult P. decipiens was much lower during the breeding season of the seals and during their southward and northward migrations within the Gulf of St. Lawrence. The incidence of P. decipiens in harp seals from the east coast of Newfoundland was very low.The relative importance of each species of seal as a vector of P. decipiens is as follows. The harbour seal is the most important in the Bay of Fundy and along the southwestern coast of Nova Scotia. Elsewhere harbour and grey seals occur in approximately equal numbers. In such localities the grey seal is probably more important than the harbour seal. The harp seal is about 100 to 200 times as numerous, while in the southwestern Gulf of St. Lawrence, as the combined populations of harbour and grey seals there. Despite this great numerical superiority the harp seal does not appear to be more important than the other seals as a host of P. decipiens.The relation between each species of seal and the incidence of larval P. decipiens in Atlantic cod (Gadus callarias) is discussed.

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.

scholarly journals A note on the harbour seal (Phoca vitulina) in the Faroe Islands

2010 ◽  
Vol 8 ◽  
pp. 143 ◽  
Author(s):  
Bjarni Mikkelsen
Keyword(s):  
19Th Century ◽  
Anthropogenic Activities ◽  
Phoca Vitulina ◽  
The Other ◽  
Harbour Seal ◽  
Faroe Islands ◽  
Grey Seal ◽  
Historical Sources ◽  
Human Settlements ◽  
Harbour Seals

The harbour seal was exterminated as a breeding species in the Faroe Islands in the mid-19th Century. Historical sources document that the harbour seal used to be a common inhabitant of the sheltered fjords where breeding occurred. It was reported to be more common than the grey seal, the other pinniped specie resident around the Faroes. But the number of harbour seals seemingly decreased as human settlements and other anthropogenic activities increased. Seal hunting was apparently already introduced by the Norse that arrived on the islands in the 7th century, a hunt that finally lead to the extermination of the harbour seal. For the last 40 years the harbour seal has only been positively identified twice in the Faroe Islands, in 2001 and 2005.

scholarly journals Monitoring trends in the abundance of harbour seals (Phoca vitulina) in Icelandic waters

2010 ◽  
Vol 8 ◽  
pp. 227 ◽  
Author(s):  
Erlingur Hauksson
Keyword(s):  
Coastal Area ◽  
East Coast ◽  
Aerial Survey ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Northwest Coast ◽  
Coastal Regions ◽  
Harbour Seals ◽  
Seal Population ◽  
Icelandic Waters

Harbour seal (Phoca vitulina) numbers along the coast of Iceland were monitored by aerial survey in the period 1980-2006. Trends in the abundance of the harbour seal population on the whole coast and in coastal regions of Iceland waters were estimated using ANCOVA on the survey counts, corrected for the influence of several covariates. Harbour seals were found in every coastal area, but were most abundant in Faxaflói, Breiðafjörður and on the northwest coast inthe beginning of this study. Harbour seal numbers declined significantly at a rate of rest = -0.04 (SE 0.005) yr-1 during this period. Decline was highest in Faxaflói and at the south coast (≅7%), while the east coast experienced a significant but lesser (≅1%) decline. Other coastal areas did not show significant trends. The northwest coast was the richest harbour seal area in Iceland in 2006. In Icelandic waters seals are commercially harvested, and unreported but probably high numbers of harbour seals are killed intentionally by shooting and accidentally in fishing geareach year. These factors likely contributed to the overall observed decline in seal numbers.

Comparison of harbour seal diets in two inshore habitats of Atlantic Canada

1996 ◽  
Vol 74 (1) ◽  
pp. 125-135 ◽  
Author(s):  
W. D. Bowen ◽  
G. D. Harrison
Keyword(s):  
Gadus Morhua ◽  
Prey Species ◽  
Atlantic Cod ◽  
Atlantic Coast ◽  
Clupea Harengus ◽  
Harbour Seal ◽  
Bay Of Fundy ◽  
Alosa Pseudoharengus ◽  
Pseudopleuronectes Americanus ◽  
Capelin Mallotus Villosus

We studied the composition of harbour seal (Phoca vitulina) diets in two areas, the lower Bay of Fundy and along the northeastern coast of Nova Scotia, that differ in prey species diversity, bottom type, and physical oceanography. Prey remains were found in 250 of 470 harbour seal stomachs collected mainly from May to September between 1988 and 1992. Although 23 taxa were identified, four species, Atlantic herring (Clupea harengus), Atlantic cod (Gadus morhua), pollock (Pollachius virens), and short-finned squid (Illex illecebrosus), accounted for 84% of the estimated biomass of prey consumed in the two areas combined. Species, such as herring and squid, that dominated the diets in both habitats, also tended to be abundant in both habitats during the summer. Atlantic cod was the principal gadoid in the Bay of Fundy, whereas pollock was most important along the Atlantic coast. Differences in prey distribution and abundance appeared to account for differences in the contribution of the alewife (Alosa pseudoharengus), winter flounder (Pseudopleuronectes americanus), hake (Urophycis spp.), and capelin (Mallotus villosus) in the diet. Pronounced interannual variation in the species composition of diets was evident in both habitats. This variation was associated with broad-scale changes in prey abundance in some cases (e.g., squid and capelin) but not in others (e.g., Atlantic cod and pollock).

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

Experiments with the Harbour Seal, Phoca vitulina, a Definitive Host of a Marine Nematode, Porrocaecum decipiens

1953 ◽  
Vol 10 (8) ◽  
pp. 539-547 ◽  
Author(s):  
D. M. Scott
Keyword(s):  
Definitive Host ◽  
Atlantic Cod ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Osmerus Mordax ◽  
Marine Nematode ◽  
The Third ◽  
Males And Females ◽  
Distinct Increase ◽  
Hippoglossoides Platessoides

Infestation experiments carried out in 1947 and 1948 showed that the harbour seal (Phoca vitulina) was a definitive host of a larval nematode found in the flesh of the Atlantic cod (Gadus callarias), smelt (Osmerus mordax), Canadian plaice (Hippoglossoides platessoides) and eelpout (Macrozoarces americanus). Adult worms recovered from experimentally infested seals were identified as Porrocaecum decipiens. Some larval Porrocaecum in the four species of fishes studied were P. decipiens.The worms lost their larval characteristics by moulting between the third and sixth day following introduction into the seal. Sexual maturation proceeded rapidly after the eleventh day and some males and females matured before the twentieth day. Maturation was accompanied by a distinct increase in size.

Comparison of the healing process in hot and cold brands applied to harbour seal pups (Phoca vitulina)

2006 ◽  
Vol 33 (5) ◽  
pp. 361 ◽  
Author(s):  
Pierre-Yves Daoust ◽  
G. Mark Fowler ◽  
Wayne T. Stobo
Keyword(s):  
Healing Rate ◽  
Healing Process ◽  
Phoca Vitulina ◽  
Hair Follicles ◽  
Harbour Seal ◽  
Short Term ◽  
Long Distance ◽  
Macroscopic Appearance ◽  
Short Term Study ◽  
Harbour Seals

Hot branding has been used for many years by researchers to identify seals from a long distance. In livestock, cold branding has been proposed as an alternative because it is thought to be less painful. The purpose of this study was to compare the healing process of hot and cold brands applied to harbour seal pups (Phoca vitulina). A total of 306 animals was branded with a unique set of four characters: three applied for 3–5 s with an iron heated to 500°C, and one applied for either 10 or 20 s with an iron frozen to –175°C. At three subsequent times over 10 weeks, 43, 41 and 51 animals, respectively, were recaptured, the macroscopic appearance of their brands recorded, and biopsies taken for microscopic examination. Cold brands had a faster healing rate than hot brands. However, they resulted in less destruction of hair follicles, and cold brands applied for 20 s caused more depigmentation. Regrowth of hair follicles could subsequently obscure brands, while depigmentation reduces the contrast between the brand and the surrounding fur. Cold brands applied for 20 s also caused more extensive deep vascular damage, which subsequently may have resulted in deeper wounds in some of these brands. Yet, macroscopically, other cold brands, or portions thereof, were almost invisible. On the basis of this short-term study, the technique of cold branding that we used in harbour seals does not appear to be as reliable as that of hot branding to provide permanent legible brands.

scholarly journals Vulnerability of harbour seals, Phoca vitulina, to transient industrial activities in the Strait of Dover

2005 ◽  
Vol 85 (4) ◽  
pp. 1015-1016 ◽  
Author(s):  
Laurent J.J. Seuront ◽  
Perrine Prinzivalli
Keyword(s):  
Interannual Variability ◽  
Industrial Wastewater ◽  
Anthropogenic Activities ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Industrial Activities ◽  
Dramatic Decline ◽  
Harbour Seals ◽  
Seal Population ◽  
Number Of Individuals

The abundance of the harbour seal (Phoca vitulina) was recorded on a tidal bar in the Dover Strait off Calais, over a six-year period between 1999 and 2004. Despite clear seasonal and interannual variability in the number of individuals hauled out on the bar, underwater activities devoted to the installation of industrial wastewater pipes conducted during seven weeks 1 km away from the bar led to a dramatic decline in the number of seals hauling out. A full 19 months after the end of the operations the harbour seal population had not recovered their initial abundance. The results of this study have critical consequences on the conservation of P. vitulina in areas impacted by anthropogenic activities.

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