scholarly journals Will Culling the Northwest Atlantic Gray Seal Population, Halichoerus grypus (Fabricius, 1791) (Carnivora: Phocidae) on Cape Cod, Massachusetts, USA Reduce the Risk of Human-White Shark Encounters?

2019 ◽  
Vol 6 (3) ◽  
pp. 75-107
Author(s):  
Kimberley Crocker Pearson ◽  
Keyword(s):  
White Shark ◽  
Halichoerus Grypus ◽  
Cape Cod ◽  
Gray Seal ◽  
Northwest Atlantic ◽  
Seal Population

scholarly journals Daily and seasonal movements of Cape Cod gray seals vary with predation risk

2020 ◽  
Vol 644 ◽  
pp. 215-228 ◽  
Author(s):  
JH Moxley ◽  
G Skomal ◽  
J Chisholm ◽  
P Halpin ◽  
DW Johnston
Keyword(s):  
Predation Risk ◽  
White Shark ◽  
Halichoerus Grypus ◽  
Cape Cod ◽  
Gray Seal ◽  
Predator Prey ◽  
Seasonal Movements ◽  
Nocturnal Foraging ◽  
And Behavior ◽  
Gray Seals

White sharks Carcharodon carcharias and gray seals Halichoerus grypus are re-establishing their ecological roles within the Northwestern Atlantic Ocean, presenting an opportunity to understand gray seal movement and at-sea behavior under predation risk. As with other shark-seal hotspots, movements to and from terrestrial haul outs can be risky for gray seals, thereby eliciting antipredator strategies. We investigated the movement and coastal behavior of gray seals on Cape Cod (USA) in relation to seasonal and diel changes in white shark activity. Analyzing 412 trips to sea by 8 seals and more than 25000 acoustic detections from 23 individual white sharks, we observed seasonally homogeneous movements in seal behavior during months with greater shark presence. During riskier months, seal behavior manifested in near-exclusive nocturnal foraging, reduced offshore ranging, and limited at-sea activity. On these nocturnal trips to sea, seals returning to haul outs tended to avoid daybreak and traversed during diel minima in shark activity. However, seals tended to depart haul outs at dusk when shark presence was maximal. As conservation efforts succeed in rebuilding depleted populations of coastal predators, studying re-emerging predator-prey interactions can enhance our understanding about the drivers of movement and behavior.

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).

Flatfish may be underestimated in the diet of gray seals (Halichoerus grypus)

2021 ◽  
pp. 1-8
Author(s):  
Michelle N. Dufault ◽  
Zachary H. Olson ◽  
Dominique M. Mellone ◽  
Kelly R. Flanders ◽  
Kathryn A. Ono
Keyword(s):  
New England ◽  
Ecological Impact ◽  
The United States ◽  
Diet Analysis ◽  
Halichoerus Grypus ◽  
Cape Cod ◽  
Gray Seal ◽  
Study Objective ◽  
Species Specific ◽  
Gray Seals

The United States east coast population of the gray seal (Halichoerus grypus (Fabricius, 1791)) was once hunted to near extirpation, but the population has since rebounded due to protection by the Marine Mammal Protection Act of 1972. Although this population growth is seen as a success by conservationists, others are concerned about the economic and ecological impact of gray seals on New England fisheries. The study objective was to quantify flatfish presence in the diet of gray seals using an analysis of prey DNA in seal scat (molecular scatology). This may reduce a potential bias in other diet analysis methods since flatfish may not be swallowed whole, and therefore, their identifying otoliths may not be present. Scats were collected from Muskeget and Monomoy islands off Cape Cod, Massachusetts, USA, in 2016, 2017, and 2018 and analyzed for flatfish presence using species-specific polymerase chain reaction (PCR) assays and a hard parts analysis using otoliths. Frequency of occurrence for flatfish species from DNA was higher than estimated in previous literature on gray seal diet and a concurrent otolith analysis of the same samples, suggesting that previous analyses may have potentially underestimated the importance of flatfish in the diet.

scholarly journals Contrasting trends in gray seal ( Halichoerus grypus ) pup production throughout the increasing northwest Atlantic metapopulation

2020 ◽  
Author(s):  
Cornelia E. Heyer ◽  
W. Don Bowen ◽  
Julian Dale ◽  
Jean‐François Gosselin ◽  
Michael O. Hammill ◽  
...  
Keyword(s):  
Halichoerus Grypus ◽  
Gray Seal ◽  
Northwest Atlantic

scholarly journals Dynamics of the formation of a differentiation track conditioned reflex to sound stimuli of a certain duration in the gray seal Halichoerus grypus Fabricius, 1791 by the methods of operant conditioning.

2021 ◽  
Vol 12 (3-2021) ◽  
pp. 7-13
Author(s):  
A.F. Berdnik ◽  
Keyword(s):  
Reaction Time ◽  
Operant Conditioning ◽  
Conditioned Reflex ◽  
Audio Signal ◽  
Halichoerus Grypus ◽  
Audio Signals ◽  
Gray Seal ◽  
And Behavior ◽  
Sound Duration

In the course of the study, a 15-year-old female gray seal was trained to press a button after displaying an audio signal for 5 seconds and ignore similar audio signals of longer or shorter duration. The conducted research has demonstrated the ability of the experimental seal to reliably differentiate sound signals with a difference in sound duration of 3 seconds. Changes in the reaction time and behavior of the seal during the demonstration of sound stimuli with distinguishable and indistinguishable time ranges are described.

scholarly journals Life cycle bioenergetics of the gray seal (Halichoerus grypus) in the Baltic Sea: Population response to environmental stress

2020 ◽  
Vol 145 ◽  
pp. 106145 ◽  
Author(s):  
Willian T.A.F. Silva ◽  
Karin C. Harding ◽  
Gonçalo M. Marques ◽  
Britt Marie Bäcklin ◽  
Christian Sonne ◽  
...  
Keyword(s):  
Life Cycle ◽  
Environmental Stress ◽  
Baltic Sea ◽  
Halichoerus Grypus ◽  
The Baltic Sea ◽  
Population Response ◽  
Gray Seal ◽  
The Baltic

Direct evidence for gray seal (Halichoerus grypus) predation and scavenging on harbor porpoises (Phocoena phocoena)

2014 ◽  
Vol 30 (4) ◽  
pp. 1542-1548 ◽  
Author(s):  
Thibaut Bouveroux ◽  
Jeremy J. Kiszka ◽  
Michael R. Heithaus ◽  
Thierry Jauniaux ◽  
Sylvain Pezeril
Keyword(s):  
Direct Evidence ◽  
Halichoerus Grypus ◽  
Phocoena Phocoena ◽  
Gray Seal ◽  
Harbor Porpoises

Seasonal variability and individual consistency in gray seal (Halichoerus grypus) isotopic niches

2019 ◽  
Vol 97 (11) ◽  
pp. 1071-1077
Author(s):  
K.M. Hernandez ◽  
A.L. Bogomolni ◽  
J.H. Moxley ◽  
G.T. Waring ◽  
R.A. DiGiovanni ◽  
...  
Keyword(s):  
United States ◽  
Seasonal Variability ◽  
Foraging Ecology ◽  
Population Level ◽  
The United States ◽  
Halichoerus Grypus ◽  
Dietary Specialization ◽  
Gray Seal ◽  
Individual Consistency ◽  
Gray Seals

Although it is often assumed that individuals in generalist populations are equivalent, recent research indicates that individual dietary specialization can be common in marine predators. Gray seals (Halichoerus grypus (Fabricius, 1791)) were considered locally extinct in United States waters by 1958 but have since recolonized the region. Although considered generalists, less is known about gray seal foraging ecology in the United States. To address this, we used carbon and nitrogen stable isotope analyses to investigate the foraging niches of adult gray seals in Massachusetts, USA. We examined skin, fur, and blood components to investigate seasonal variability and individual consistency in foraging niches, and serially sampled vibrissae to quantify the degree of individual foraging specialization in this population. Our results suggest that seals shift from coastal foraging habitats before molt to offshore habitats after molt, with a coincident shift from higher to lower trophic-level prey. Adult gray seals also exhibited individual consistency in foraging niches independent of population-level shifts and reflect a generalist population composed of individual foraging specialists. These findings serve as a baseline for subsequent research on gray seals in United States waters that could help to determine the mechanisms which promote individual specialization in this population.

METAL SENSITIVITY OF MARINE MAMMALS: A CASE STUDY OF A GRAY SEAL (HALICHOERUS GRYPUS)

2006 ◽  
Vol 22 (4) ◽  
pp. 985-996 ◽  
Author(s):  
A. Kakuschke ◽  
E. Valentine-Thon ◽  
S. Fonfara ◽  
S. Griesel ◽  
U. Siebert ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Halichoerus Grypus ◽  
Gray Seal ◽  
Metal Sensitivity

Respiratory properties of blood of the gray seal,Halichoerus grypus

1982 ◽  
Vol 149 (1) ◽  
pp. 49-56 ◽  
Author(s):  
George N. Lapennas ◽  
Robert Blake Reeves
Keyword(s):  
Halichoerus Grypus ◽  
Gray Seal
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