| widespread neonatal infection with phocid herpesvirus 1 in free-ranging and stranded grey seals halichoerus grypus. | phocid herpesvirus 1 (phhv-1) is known to infect grey seals halichoerus grypus but little is known about its pathogenicity or true prevalence in this species. to investigate the prevalence of and risk factors associated with phv-1 infection, nasal swabs were collected from grey seal pups and yearlings on the isle of may, a well-studied grey seal breeding colony, and from stranded grey seal pups submitted to a rehabilitation centre. phhv-1 nucleic acids were detected in nasal swabs from 58% (52/9 ... | 2019 | 31019131 |
| classifying grey seal behaviour in relation to environmental variability and commercial fishing activity - a multivariate hidden markov model. | classifying movement behaviour of marine predators in relation to anthropogenic activity and environmental conditions is important to guide marine conservation. we studied the relationship between grey seal (halichoerus grypus) behaviour and environmental variability in the southwestern baltic sea where seal-fishery conflicts are increasing. we used multiple environmental covariates and proximity to active fishing nets within a multivariate hidden markov model (hmm) to quantify changes in moveme ... | 2019 | 30948786 |
| long-term sound and movement recording tags to study natural behavior and reaction to ship noise of seals. | the impact of anthropogenic noise on marine fauna is of increasing conservation concern with vessel noise being one of the major contributors. animals that rely on shallow coastal habitats may be especially vulnerable to this form of pollution.very limited information is available on how much noise from ship traffic individual animals experience, and how they may react to it due to a lack of suitable methods. to address this, we developed long-duration audio and 3d-movement tags (dtags) and depl ... | 2019 | 30891202 |
| sensitivity of multispecies maximum sustainable yields to trends in the top (marine mammals) and bottom (primary production) compartments of the southern north sea food-web. | in marine ecosystems, maximum sustainable yield considerations are affected by any substantial changes that occur in the top and bottom compartments of the food-web. this study explores how the southern north sea's fisheries may need to adjust their fishing efforts to maintain optimum yields of sole, plaice, cod and brown shrimps under increased marine mammal populations and a reduced primary productivity. we constructed plausible scenarios of ongoing food-web changes using the results of bayesi ... | 2019 | 30689649 |
| complementary methods assessing short and long-term prey of a marine top predator ‒ application to the grey seal-fishery conflict in the baltic sea. | the growing grey seal (halichoerus grypus) population in the baltic sea has created conflicts with local fisheries, comparable to similar emerging problems worldwide. adequate information on the foraging habits is a requirement for responsible management of the seal population. we investigated the applicability of available dietary assessment methods by comparing morphological analysis and dna metabarcoding of gut contents (short-term diet; n = 129/125 seals, respectively), and tissue chemical m ... | 2019 | 30601857 |
| spatial variation in a top marine predator's diet at two regionally distinct sites. | in ecological studies it is often assumed that predator foraging strategies and resource use are geographically and seasonally homogeneous, resulting in relatively static trophic relationships. however, certain centrally placed foragers (e.g. seals) often have terrestrial sites for breeding, resting, and moulting that are geographically distinct, and associated with different habitat types. therefore, accurate estimations of predator diet at relevant spatial and temporal scales are key to unders ... | 2019 | 30601852 |
| the necessity of a holistic approach when managing marine mammal-fisheries interactions: environment and fisheries impact are stronger than seal predation. | seal populations are recovering in many regions around the world and, consequently, they are increasingly interacting with fisheries. we used an ecopath with ecosim model for the offshore central baltic sea to investigate the interactions between the changes in fish stocks and grey seal (halichoerus grypus) population under different fishing and environmental scenarios for the twenty-first century. the assumed climate, eutrophication and cod (gadus morhua) fisheries scenarios modified seal preda ... | 2019 | 30536186 |
| prevalence of alopecia in gray seals halichoerus grypus atlantica in massachusetts, usa, 2004-2013. | there has been an increase in the presence of alopecia among gray seals halichoerus grypus atlantica in massachusetts, usa. to understand the prevalence and describe the presentation of this condition, data records and photographs of 10070 gray seals from 2004-2013 were reviewed; there were sufficient data to confidently assess the presence or absence of alopecia in 2134 seals. mild hair loss presented in multifocal patches with minimal to no skin lesions or erythema. in severe cases, alopecia w ... | 2018 | 30459289 |
| new approach to stress research in phocids-potential of dehydroepiandrosterone and cortisol/dehydroepiandrosterone ratio as markers for stress in harbor seals ( phoca vitulina) and gray seals ( halichoerus grypus). | cortisol is known to reflect the level of the stress response. however, measuring the cortisol concentration only once fails to provide sufficient information about the duration of the stress exposure. moreover, handling is an acute stressor and increases cortisol secretion especially in wildlife species. yet, in phocids reliable indicators are missing that reflect potential chronic effects of stress. the adrenal-derived steroid hormone dehydroepiandrosterone (dhea) has been described as biomark ... | 2018 | 30212331 |
| genomic signatures of population bottleneck and recovery in northwest atlantic pinnipeds. | population increases over the past several decades provide natural settings in which to study the evolutionary processes that occur during bottleneck, growth, and spatial expansion. we used parallel natural experiments of historical decline and subsequent recovery in two sympatric pinniped species in the northwest atlantic, the gray seal (halichoerus grypus atlantica) and harbor seal (phoca vitulina vitulina), to study the impact of recent demographic change in genomic diversity. using restricti ... | 2018 | 30038760 |
| a novel quantitative real-time pcr diagnostic assay for seal heartworm (acanthocheilonema spirocauda) provides evidence for possible infection in the grey seal (halichoerus grypus). | the distinct evolutionary pressures faced by pinnipeds have likely resulted in strong coevolutionary ties to their parasites (leidenberger et al., 2007). this study focuses on the phocid seal filarial heartworm species acanthocheilonema spirocauda. a. spirocauda is known to infect a variety of phocid seals, but does not appear to be restricted to a single host species (measures et al., 1997; leidenberger et al., 2007; lehnert et al., 2015). however, to date, seal heartworm has never been reporte ... | 2018 | 29988808 |
| accumulation of pbdes in stranded harp (pagophilus groenlandicus) and hooded seals (cystophora cristata) from the northeastern united states. | polybrominated diphenyl ethers (pbdes) are highly lipophilic components of brominated flame retardants that are environmentally persistent and bioaccumulate. pbdes are taken up from the gastrointestinal tract and accumulate mainly in fat depots and liver tissues. seal species inhabiting arctic and sub-arctic regions can have upwards of 30% of their body mass composed of blubber. when those blubber stores are mobilized for energy, stored toxicants are also released into circulation. most studies ... | 2018 | 29706368 |
| brucella pinnipedialis in grey seals ( halichoerus grypus) and harbor seals ( phoca vitulina) in the netherlands. | brucellosis is a zoonotic disease with terrestrial or marine wildlife animals as potential reservoirs for the disease in livestock and human populations. the primary aim of this study was to assess the presence of brucella pinnipedialis in marine mammals living along the dutch coast and to observe a possible correlation between the presence of b. pinnipedialis and accompanying pathology found in infected animals. the overall prevalence of brucella spp. antibodies in sera from healthy wild grey s ... | 2018 | 29697310 |
| google haul out: earth observation imagery and digital aerial surveys in coastal wildlife management and abundance estimation. | as the sampling frequency and resolution of earth observation imagery increase, there are growing opportunities for novel applications in population monitoring. new methods are required to apply established analytical approaches to data collected from new observation platforms (e.g., satellites and unmanned aerial vehicles). here, we present a method that estimates regional seasonal abundances for an understudied and growing population of gray seals (halichoerus grypus) in southeastern massachus ... | 2017 | 29599542 |
| assessing the disturbance potential of small unoccupied aircraft systems (uas) on gray seals (halichoerus grypus) at breeding colonies in nova scotia, canada. | the use of small unoccupied aircraft systems (uas) for ecological studies and wildlife population assessments is increasing. these methods can provide significant benefits in terms of costs and reductions in human risk, but little is known if uas-based approaches cause disturbance of animals during operations. to address this knowledge gap, we conducted a series of uas flights at gray seal breeding colonies on hay and saddle islands in nova scotia, canada. using a small fixed-wing uas, we assess ... | 2018 | 29576950 |
| bio accumulation of radioactive caesium in marine mammals in the baltic sea - reconstruction of a historical time series. | radionuclides from the chernobyl accident in 1986 still circulate in the baltic marine ecosystem and activity levels in water, sediments and fish species such as herring and perch are monitored annually. however, the activity levels of radionuclides in marine mammals have only been sporadically reported. tissue samples from a museum collection were analysed in two species of seals, and the trends over time in activity level of radioactive caesium (cs-137) after the chernobyl accident were recons ... | 2018 | 29518725 |
| evaluating the use of stable isotope analysis to infer the feeding ecology of a growing us gray seal (halichoerus grypus) population. | gray seals (halichoerus grypus) have been rapidly recolonizing the northeast us coast, eliciting concern from the fishing industry. however, the ecological effect of this recovery is still unknown and as such, research is needed to better understand how the diet composition of gray seals in us waters will contribute to the ecological impact. while previous research on seal diets has focused on the analysis of hard prey remains, stable isotope analysis presents an alternative method that can be u ... | 2018 | 29466372 |
| prevalence and molecular characterisation of acanthocephala in pinnipedia of the north and baltic seas. | harbour seals (phoca vitulina) and grey seals (halichoerus grypus) are final hosts of acanthocephalans in the german north and baltic seas. parasitic infections in seals can cause pathological changes, which may result in deteriorated health of the host. common gastrointestinal parasites of harbour and grey seals are acanthocephalans and a number of 275 of 2460 (11.2%) investigated seals from 1996 to 2013 were infected with corynosoma spp. (acanthocephala, polymorphidae). the prevalence showed a ... | 2018 | 29387535 |
| bayesian joint models with inla exploring marine mobile predator-prey and competitor species habitat overlap. | understanding spatial physical habitat selection driven by competition and/or predator-prey interactions of mobile marine species is a fundamental goal of spatial ecology. however, spatial counts or density data for highly mobile animals often (1) include excess zeros, (2) have spatial correlation, and (3) have highly nonlinear relationships with physical habitat variables, which results in the need for complex joint spatial models. in this paper, we test the use of bayesian hierarchical hurdle ... | 2017 | 29242741 |
| rapid changes in atlantic grey seal milk from birth to weaning - immune factors and indicators of metabolic strain. | true seals have the shortest lactation periods of any group of placental mammal. most are capital breeders that undergo short, intense lactations, during which they fast while transferring substantial proportions of their body reserves to their pups, which they then abruptly wean. milk was collected from atlantic grey seals (halichoerus grypus) periodically from birth until near weaning. milk protein profiles matured within 24 hours or less, indicating the most rapid transition from colostrum to ... | 2017 | 29170469 |
| intrinsic and extrinsic factors drive ontogeny of early-life at-sea behaviour in a marine top predator. | young animals must learn to forage effectively to survive the transition from parental provisioning to independent feeding. rapid development of successful foraging strategies is particularly important for capital breeders that do not receive parental guidance after weaning. the intrinsic and extrinsic drivers of variation in ontogeny of foraging are poorly understood for many species. grey seals (halichoerus grypus) are typical capital breeders; pups are abandoned on the natal site after a brie ... | 2017 | 29138511 |
| impact of ocean warming on sustainable fisheries management informs the ecosystem approach to fisheries. | an integrated ecosystem model including fishing and the impact of rising temperatures, relative to species' thermal ranges, was used to assess the cumulative effect of future climate change and sustainable levels of fishing pressure on selected target species. historically, important stocks of cod and whiting showed declining trends caused by high fisheries exploitation and strong top-down control by their main predators (grey seals and saithe). in a no-change climate scenario these stocks recov ... | 2017 | 29044134 |
| prevalence of presenting conditions in grey seal pups (halichoerus grypus) admitted for rehabilitation. | a retrospective survey was performed on the presenting conditions of 205 live grey seal pups (halichoerus grypus) admitted to the cornish seal sanctuary in gweek, united kingdom between may 2005 and march 2011. the purpose of the survey was to examine the prevalence of various presenting signs at the sanctuary. the presenting signs were classified into nine non-mutually exclusive categories: ocular disorders, nasal disorders, oral disorders, respiratory disorders, orthopaedic disorders, puncture ... | 2015 | 29061924 |
| heavy metal content in liver and kidneys of grey seals (halichoerus grypus) in various life stages correlated with metallothionein levels: some metal-binding characteristics of this protein. | liver and kidneys from grey seals (halichoerus grypus) in their natural habitats in norwegian waters contain high levels of cd and hg as well as metallothionein (mt). the data show significant placental transfer of heavy metals in seals. the mt concentrations were higher in fetus liver and kidneys than in the liver and kidneys of juveniles and adults. a significantly higher proportion of the total cd and cu, as compared to zn and hg, in fetal liver was associated with mt. only low amounts of met ... | 1999 | 29857630 |
| a review of the sealworm problem: biology, implications and solutions. | the life cycle and geographic distribution of the sealworm ( phocanema decipiens ) are reviewed. also discussed is the temperature tolerance of the third stage larva as well as its public health implications. it is concluded that there ought to be no public health hazards associated with the sealworm as long as people continue to process seafood properly. correlation between the increase in the grey seal population and the increase in the rate of sealworm infestation in cod over the last decades ... | 1987 | 30965534 |