scholarly journals First record of a melanistic grey seal (Halichoerus grypus) in Galicia (NW Spain)

2021 ◽  
Vol 33 ◽  
pp. 61-63
Author(s):  
Alfredo López ◽  
Uxía Vázquez ◽  
Pablo Covelo
Keyword(s):  
First Record ◽  
Halichoerus Grypus ◽  
Grey Seal ◽  
Nw Spain

First Record of a Grey Seal (Halichoerus grypus) Predating a Tope Shark (Galeorhinus galeus) in the UK

2021 ◽  
Vol 47 (5) ◽  
pp. 465-469
Author(s):  
Georgia Catherine Anne Jones ◽  
Andrew John Roberts ◽  
David George Edwards
Keyword(s):  
First Record ◽  
Halichoerus Grypus ◽  
Grey Seal ◽  
Galeorhinus Galeus ◽  
The Uk

Utilizing next-generation sequencing to identify prey DNA in western North Atlantic grey seal Halichoerus grypus diet

2020 ◽  
Vol 655 ◽  
pp. 227-240
Author(s):  
KR Flanders ◽  
ZH Olson ◽  
KA Ono
Keyword(s):  
Next Generation Sequencing ◽  
Feeding Habits ◽  
Atlantic Menhaden ◽  
Halichoerus Grypus ◽  
Frequency Of Occurrence ◽  
Grey Seal ◽  
Next Generation ◽  
Significant Difference ◽  
Generation Sequencing ◽  
Seal Diet

Increasing grey seal Halichoerus grypus abundance in coastal New England is leading to social, political, economic, and ecological controversies. Central to these issues is the foraging ecology and diet composition of the seals. We studied grey seal feeding habits through next-generation sequencing of prey DNA using 16S amplicons from seal scat (n = 74) collected from a breeding colony on Monomoy Island in Massachusetts, USA, and report frequency of occurrence and relative read abundance. We also assigned seal sex to scat samples using a revised PCR assay. In contrast to current understanding of grey seal diet from hard parts and fatty acid analysis, we found no significant difference between male and female diet measured by alpha and beta diversity. Overall, we detected 24 prey groups, 18 of which resolved to species. Sand lance Ammodytes spp. were the most frequently consumed prey group, with a frequency of occurrence (FO) of 97.3%, consistent with previous studies, but Atlantic menhaden Brevoortia tyrannus, the second most frequently consumed species (FO = 60.8%), has not previously been documented in US grey seal diet. Our results suggest that a metabarcoding approach to seal food habits can yield important new ecological insights, but that traditional hard parts analysis does not underestimate consumption of Atlantic cod Gadus morhua (FO = 6.7%, Gadidae spp.) and salmon Salmo salar (FO = 0%), 2 particularly valuable species of concern.

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 Does predation by grey seals (Halichoerus grypus) affect Bothnian Sea herring stock estimates?

2012 ◽  
Vol 69 (8) ◽  
pp. 1448-1456 ◽  
Author(s):  
Anna Gårdmark ◽  
Örjan Östman ◽  
Anders Nielsen ◽  
Karl Lundström ◽  
Olle Karlsson ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Halichoerus Grypus ◽  
Grey Seal ◽  
Older Individuals ◽  
Standard Assessment ◽  
Abundance Estimates ◽  
Stock Biomass ◽  
Key Species ◽  
Spawning Stock ◽  
Bothnian Sea

Abstract Gårdmark, A., Östman, Ö., Nielsen, A., Lundström K., Karlsson O., Pönni, J., and Aho, T. 2012. Does predation by grey seals (Halichoerus grypus) affect Bothnian Sea herring stock estimates? – ICES Journal of Marine Science, 69: . Mortality of small pelagic fish due to marine mammals is generally considered to be low compared with other sources of mortality. With recent recoveries of marine mammal predators worldwide, this may no longer hold. The grey seal (Halichoerus grypus) population in the Bothnian Sea has increased fivefold since 1985. Its main prey, herring (Clupea harrengus), is a key species for fisheries in the region. Yet, current stock assessments assume constant natural mortality, leading to a risk of biased stock estimates with increasing predation and misleading analyses of herring population dynamics. We estimated grey seal predation from diet data and reanalysed herring spawning stock biomass (SSB) during 1973–2009. Accounting for predation increased the herring SSB 16% (maximum 19%), but this was within the confidence intervals when ignoring predation. Although mortality in older individuals was inflated when accounting for seal predation, this did not change the conclusions about drivers of herring dynamics. Accounting for grey seal predation is important for abundance estimates of old herring, but currently not for SSB estimates, given the great uncertainties in the standard assessment. The grey seal impact on Bothnian Sea herring will need to be reassessed if stock age composition, grey seal feeding preferences, or total stock development change.

scholarly journals A Short Investigation into the Habits, Abundance, and Species of Seals on the North Cornwall Coast

1934 ◽  
Vol 19 (2) ◽  
pp. 189-501 ◽  
Author(s):  
G. A. Steven
Keyword(s):  
Relative Abundance ◽  
Direct Evidence ◽  
Phoca Vitulina ◽  
Halichoerus Grypus ◽  
Grey Seal ◽  
The North ◽  
Single Night ◽  
Considerable Size

1. In the course of three trips to the herring grounds in the vicinity of St. Ives five seals were sighted. Seven others were also seen at various other times and places in the course of five days spent in that locality.2. During a single night at sea in Port Isaac Bay eight seals were sighted.3. It was obvious from the movements of certain of the seals observed on the fishing grounds that they were attracted to the herring nets.4. Direct evidence that the seals actually remove fish from the nets was not obtained.5. Damage done to drift nets by seals is negligible.6. Grey Seals (Halichœrus grypus) are present in considerable numbers, and are probably the commonest seals in Cornish waters.7. Brown Seals (Phoca vitulina) appear to be few—they may even be rare—around Cornwall.8. There is at least one seal colony of considerable size in certain caves near Boscastle. This appears to consist of Grey Seals. Probably other such colonies exist on the Cornish coast.9. Clupeoid remains have been found in two out of the three Grey Seal stomachs which have been examined.10. Further and more exact knowledge of the habits and relative abundance of Grey and Brown Seals around the Cornish coast is desirable.

Pup production and population trends of the grey seal (Halichoerus grypus) in the Gulf of St. Lawrence

1998 ◽  
Vol 55 (2) ◽  
pp. 423-430 ◽  
Author(s):  
M O Hammill ◽  
G B Stenson ◽  
R A Myers ◽  
W T Stobo
Keyword(s):  
Population Trends ◽  
Annual Rate ◽  
Halichoerus Grypus ◽  
Grey Seal ◽  
Northwest Atlantic ◽  
Mark Recapture ◽  
Seal Population ◽  
Independent Estimate ◽  
Anticosti Island

Grey seal (Halichoerus grypus) pup production of the Gulf of St. Lawrence component of the Northwest Atlantic grey seal population was determined for the 1984-1986 and 1989-1990 periods using mark-recapture methods. Pup production estimates based on recaptures from shot samples from Anticosti Island ranged from 5436 (SE = 672) to 6955 (SE = 1183) for 1984-1986. An independent estimate for 1984-1986, based on animals captured on Sable Island, was 7431 (SE = 1414) to 8633 (SE = 2827). Mark-recapture estimates of pup production for 1989 and 1990 from shot samples collected from Anticosti Island were 8825 (SE = 3164) and 9156 (SE = 2652), respectively. The estimates based on animals captured on Sable Island varied from 7295 (SE = 2118) to 8116 (SE = 846) for 1989-1990. Both the Anticosti Island and Sable Island recovery samples underestimate 1989 pup production due to hunting which removed 1612 pups from the population before they could disperse. The Gulf component of the Northwest Atlantic grey seal population is increasing at an annual rate of 7.4% (SE = 2.2).

Patterns of parental relatedness and pup survival in the grey seal (Halichoerus grypus)

2004 ◽  
Vol 13 (8) ◽  
pp. 2365-2370 ◽  
Author(s):  
K. BEAN ◽  
W. AMOS ◽  
P. P. POMEROY ◽  
S. D. TWISS ◽  
T. N. COULSON ◽  
...  
Keyword(s):  
Halichoerus Grypus ◽  
Grey Seal ◽  
Pup Survival
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