Halichoerus Research Articles

Describing whisker morphology of the Carnivora.

One of the largest ecological transitions in carnivoran evolution was the shift from terrestrial to aquatic lifestyles, which has driven morphological diversity in skulls and other skeletal structures. In this paper, we investigate the association between those lifestyles and whisker morphology. However, comparing whisker morphology over a range of species is challenging since the number of whiskers and their positions on the mystacial pads vary between species. Also, each whisker will be at a different stage of growth and may have incurred damage due to wear and tear. Identifying a way to easily capture whisker morphology in a small number of whisker samples would be beneficial. Here, we describe individual and species variation in whisker morphology from two-dimensional scans in red fox, European otter and grey seal. A comparison of long, caudal whiskers shows inter-species differences most clearly. We go on to describe global whisker shape in 24 species of carnivorans, using linear approximations of curvature and taper, as well as traditional morphometric methods. We also qualitatively examine surface texture, or the presence of scales, using scanning electron micrographs. We show that gross whisker shape is highly conserved, with whisker curvature and taper obeying simple linear relationships with length. However, measures of whisker base radius, length, and maybe even curvature, can vary between species and substrate preferences. Specifically, the aquatic species in our sample have thicker, shorter whiskers that are smoother, with less scales present than those of terrestrial species. We suggest that these thicker whiskers may be stiffer and able to maintain their shape and position during underwater sensing, but being stiffer may also increase wear.

Stay close, but not too close: aerial image analysis reveals patterns of social distancing in seal colonies.

Many species aggregate in dense colonies. Species-specific spatial patterns provide clues about how colonies are shaped by various (a)biotic factors, including predation, temperature regulation or disease transmission. Using aerial imagery, we examined these patterns in colonies on land of two sympatric seal species: the harbour seal and grey seal. Results show that the density of grey seals on land is twice as high as that of harbour seals. Furthermore, the nearest neighbour distance (NND) of harbour seals (median = 1.06 m) is significantly larger than that of grey seals (median = 0.53 m). Avoidance at small distances (i.e. social distancing) was supported by spatial simulation: when the observed seal locations were shuffled slightly, the frequency of the smallest NNDs (0-25 cm) increased, while the most frequently observed NNDs decreased. As harbour seals are more prone to infectious diseases, we hypothesize that the larger NNDs might be a behavioural response to reduce pathogen transmission. The approach presented here can potentially be used as a practical tool to differentiate between harbour and grey seals in remote sensing applications, particularly in low to medium resolution imagery (e.g. satellite imagery), where morphological characteristics alone are insufficient to differentiate between species.

Haul-out patterns of the Baltic grey seal (Halichoerus grypus) in the suburbs of a metropolis

In this study, we investigated the haul-out patterns of the Baltic grey seal in the coastal area adjacent to the metropolitan city, Saint Petersburg, during the ice-free seasons of 2017-2022. Grey seals occupied stony banks near Kotlin Island, in the easternmost part of the Gulf of Finland. The censuses were carried out from the island shore during evening hours. The number of seals reached 70 during the survey. Contrary to the common trend reported in similar studies, the annual minimum in seal abundance (May and June) coincided with the peak of moulting. Active use of the haul-out site was observed between July and November, implying that eastward movements of the grey seals take place in the Gulf of Finland in the post-moulting period. Wind speed and sea state interfered with the seal hauling out throughout the year, whereas the relationship with air temperature varied seasonally. Cloud cover, atmospheric pressure, wind direction and sea level had no impact on the seal number, though the fluctuations in sea level reduced the haul-out space. The tendency of the seals to haul out towards and after the sunset was determined. The most frequent sources of human disturbance were light planes (0.45 ± 0.12 confidence interval, per count) and powerboats (0.41 ± 0.14 confidence interval, per count), but only the powerboats significantly decreased the seal number. We found that the seals used the banks concurrently with seabirds. The area of Kotlin Island presumably attracts the seals by the diversity of prey items in the estuary of the Neva River. Establishing of a marine protected area and physical marking of the water space around the haul-out site are recommended.

Individual Quality Drives Life History Variation in a Long-Lived Marine Predator.

AbstractIndividual quality and environmental conditions may mask or interact with energetic trade-offs in life history evolution. Deconstructing these sources of variation is especially difficult in long-lived species that are rarely observed on timescales long enough to disentangle these effects. Here, we investigated relative support for variation in female quality and costs of reproduction as factors shaping differences in life history trajectories using a 32-year dataset of repeated reproductive measurements from 273 marked, known-age female gray seals (Halichoerus grypus). We defined individual reproductive investment using two traits, reproductive frequency (a female's probability of breeding) and provisioning performance (offspring weaning mass). Fitted hierarchical Bayesian models identified individual investment relative to conspecifics (over a female's entire life and in three age classes) and subsequently estimated how these investment metrics and the Atlantic Multidecadal Oscillation are associated with longevity. Individual differences (i.e., quality) contributed a large portion of the variance in reproductive traits. Females that consistently invest well in their offspring relative to other females survive longer. The best-supported model estimated survival as a function of age class-specific provisioning performance, where late-life performance was particularly variable and had the greatest impact on survival, possibly indicating individual variation in senescence. There was no evidence to support a trade-off in reproductive performance and survival at the individual level. Overall, these results suggest that in gray seals, individual quality is a stronger driver in life history variation than individual strategies resulting from energetic trade-offs.

Directional Orientation of Harbor (Phoca vitulina) and Gray (Halichoerus grypus) Seals at Haul-out Locations in New York City

Directional Orientation of Harbor (Phoca vitulina) and Gray (Halichoerus grypus) Seals at Haul-out Locations in New York City

Application of tonal audiometry methods to assess the hearing of grey seals in air and water environments

Anthropogenic noise load on the traditional habitats of marine mammals continues to increase due to the active development of the Arctic zone. The study of the hearing of Arctic seals is of great importance for the development of measures to reduce the impact of technogenic noise. During the study, a group of ten grey seals of different ages and genders has been trained to press a special key when demonstrating a pure tone sound with a frequency from the standard and extended set of frequencies recommended for pure tone audiometry. The experiments have been carried out by placing the key and the sound source in air and water (at a depth of 2 m) environment. The main indicator is the reaction time of the seal to the demonstrated stimulus. For each seal, individual audiograms for hearing in air and in water have been compiled using 32 frequencies. An analysis of the data obtained has shown that the reaction time can serve as an individual indicator in the study of the hearing of grey seals reflecting their age characteristics. According to the response time to sounds with different tone frequencies it is possible to establish biologically significant and indifferent frequencies for grey seals.

Umjetno mlijeko za novorođenu siročad divljih životinja

Milk is a very complex nutrient and differs significantly between species. Monotreme and Marsupial milk contains only trace amounts of lactose, whereas in Eutherian species, lactose is the predominant saccharide. Within the Eutheria, the composition varies from 8.5% in Indian rhinoceros to 63.8% in Grey seal in concentration; from 0.3% in Indian rhinoceros to 9.3% in elephants in total fat; from 1.2% in Indian rhinoceros to 12.8% in Fin whale in total protein; and finally from 0.8% in Great panda to 6.5% in Indian rhinoceros in lactose. Milk components change during lactation and, especially in Marsupials, this should be considered in artificial feeding. Other factors to be taken into account are the amino acid panel, whey and casein fractions, iron and immunological components. In wildlife nursing, we often come across orphaned neonates that require artificial feeding. However, there are no specific formulas for each wildlife baby. The aim of this review is to compare which artificial milk replacer is best suited for selected species of wildlife neonates.

Occurrence and antimicrobial resistance of Salmonella species and potentially pathogenic Escherichia coli in free-living seals of Canadian Atlantic and eastern Arctic waters.

Seal populations in Canadian waters provide sustenance to coastal communities. There is potential for pathogenic and/or antimicrobial-resistant bacteria to transfer to humans through inadvertent faecal contamination of seal products. The objective of this study was to investigate the occurrence and potential antimicrobial resistance of Salmonella spp., Escherichia coli and Listeria monocytogenes in faecal samples collected from grey seals (Halichoerus grypus) in the Gulf of St. Lawrence and from ringed seals (Pusa hispida) in Frobisher Bay and Eclipse Sound, Nunavut, Canada. Grey seals were harvested during commercial hunts or during scientific sampling; ringed seals were collected by Inuit hunters during subsistence harvests. Virulence genes defining pathogenic E. coli were identified by PCR, and antimicrobial susceptibility testing was performed on recovered isolates. In grey seals, E. coli was detected in 34/44 (77%) samples, and pathogenic E. coli (extraintestinal E. coli [ExPEC], enteropathogenic E. coli [EPEC] or ExPEC/EPEC) was detected in 13/44 (29%) samples. Non-susceptibility to beta-lactams and quinolones was observed in isolates from 18 grey seals. In ringed seals from Frobisher Bay, E. coli was detected in 4/45 (9%) samples; neither virulence genes nor antimicrobial resistance was detected in these isolates. In ringed seals from Eclipse Sound, E. coli was detected in 8/50 (16%) samples and pathogenic E. coli (ExPEC and ExPEC/EPEC) in 5/50 (10%) samples. One seal from Eclipse Sound had an E. coli isolate resistant to beta-lactams. A monophasic Salmonella Typhimurium was recovered from 8/50 (16%) seals from Eclipse Sound. All Salmonella isolates were resistant to ampicillin, streptomycin, sulfisoxazole and tetracycline. L. monocytogenes was not detected in any sample. These findings suggest that seals may act as important sentinel species and as reservoirs or vectors for antimicrobial-resistant and virulent E. coli and Salmonella species. Further characterization of these isolates would provide additional insights into the source and spread of antimicrobial resistance and virulence genes in these populations of free-living seals.

Reassessing the management criteria of growing seal populations: The case of Baltic grey seal and coastal fishery

The unintended consequences of marine mammal recoveries have created complex issues for resource managers to solve. In the Baltic Sea, the grey seal (Halichoerus grypus) population has increased rapidly during recent decades, and the conflict between seal conservation and fishery has escalated. Although the magnitude of economic losses varies depending on the type of fisheries, there is strong evidence that the grey seal population negatively impacts coastal fisheries and indirectly threatens the cultural heritage connected to it. The current management paradigm is biased towards the preservation of seal populations and it is failing to adequately consider socio-economic impacts of seal population. There is a need to strike a balance between seal conservation and the viability of coastal fisheries, taking into consideration local circumstances. This paper contributes to resolving this problem by assessing the existing governance arrangement. We conclude that the inconsistencies between and within different regulatory frameworks in HELCOM recommendations and European Union law are a structural constraint to tackling the problem. Further to that, some of the existing management criteria applicable to Baltic grey seal population need to be revisited by giving more consideration to regional conditions within the Baltic Sea. For instance, if the data shows that the Baltic grey seal population in its core distribution area has reached a sustainable status and is no longer at risk, then the use of peripheral areas as an indication of inadequate state of the entire Baltic Sea grey seal population is questionable.

Large offspring have enhanced lifetime reproductive success: Long-term carry-over effects of weaning size in gray seals (Halichoerus grypus).

An individual's size in early stages of life may be an important source of individual variation in lifetime reproductive performance, as size effects on ontogenetic development can have cascading physiological and behavioral consequences throughout life. Here, we explored how size-at-young influences subsequent reproductive performance in gray seals (Halichoerus grypus) using repeated encounter and reproductive data on a marked sample of 363 females that were measured for length after weaning, at ~4 weeks of age, and eventually recruited to the Sable Island breeding colony. Two reproductive traits were considered: provisioning performance (mass of weaned offspring), modeled using linear mixed effects models; and reproductive frequency (rate at which a female returns to breed), modeled using mixed effects multistate mark-recapture models. Mothers with the longest weaning lengths produced pups 8 kg heavier and were 20% more likely to breed in a given year than mothers with the shortest lengths. Correlation in body lengths between weaning and adult life stages, however, is weak: Longer pups do not grow to be longer than average adults. Thus, covariation between weaning length and future reproductive performance appears to be a carry-over effect, where the size advantages afforded in early juvenile stages may allow enhanced long-term performance in adulthood.

Detection of Novel Poxvirus from Gray Seal (Halichoerus grypus), Germany

We detected a novel poxvirus from a gray seal (Halichoerus grypus) from the North Sea, Germany. The juvenile animal showed pox-like lesions and deteriorating overall health condition and was finally euthanized. Histology, electron microscopy, sequencing, and PCR confirmed a previously undescribed poxvirus of the Chordopoxvirinae subfamily, tentatively named Wadden Sea poxvirus.

Heartworms in Halichoerus grypus: first records of Acanthocheilonema spirocauda (Onchocercidae; Filarioidea) in 2 grey seals from the North Sea.

The assumed definitive host of the heartworm Acanthocheilonema spirocauda (Onchocerdidae; Filarioidea) is the harbour seal (Phoca vitulina). This filaroid nematode parasitizing in cardiac ventricles and blood vessel lumina of harbour seals (P. vitulina) has a low prevalence and seldom causes severe health impacts. The seal louse (Echinophthirius horridus) is the assumed intermediate host for transmission of A. spirocauda filariae between seals, comprising a unique parasite assembly conveyed from the terrestrial ancestors of pinnipeds. Although grey seals (Halichoerus grypus) are infected by seal lice, heartworm infection was not verified. Analysing a longterm dataset compiled over decades (1996–2021) of health monitoring seals along the German coasts comprising post mortem investigations and archived parasites, 2 cases of A. spirocauda infected male grey seals were detected. Tentative morphological identification was confirmed with molecular tools by sequencing a section of mtDNA COI and comparing nucleotide data with available heartworm sequence. This is the first record of heartworm individuals collected from the heart of grey seals at necropsy. It remains puzzling why heartworm infection occur much less frequently in grey than in harbour seals, although both species use the same habitat, share mixed haul-outs and consume similar prey species. If transmission occurs directly via seal louse vectors on haul-outs, increasing seal populations in the North- and Baltic Sea could have density dependent effects on prevalence of heartworm and seal louse infections. It remains to be shown how species-specificity of filarial nematodes as well as immune system traits of grey seals influence infection patterns of A. spirocauda.

Seals, fish, humans and parasites in the Baltic: ecology, evolution and history.

Evolutionary and ecological processes affecting the interactions between hosts and parasites in the aquatic environment are at display in the Baltic Sea, a young and ecologically unstable marine ecosystem, where fluctuating abiotic and biotic factors affect the parasitofauna in fish. The dynamic infections of Baltic cod, a subpopulation of the Atlantic cod (Gadus morhua Linnaeus), with third stage anisakid nematode larvae of Pseudoterranova decipiens (Krabbe, 1878) and Contracaecum osculatum (Rudolphi, 1802) have increased following a significant increase of the Baltic grey seal Halichoerus grypus (Fabricius) population in the region. Cod serves as a paratenic host and marine mammals, pinnipeds, are definitive hosts releasing parasite eggs, with faeces, to the marine environment, where embryonation and hatching of the third stage larva take place. The parasite has no obligate intermediate hosts, but various invertebrates, smaller fish and cod act as paratenic hosts transmitting the infection to the seal. Contracaecum osculatum has an impact on the physiological performance of the cod, which optimises transmission of the larva from fish to seal. Thus, a muscle mass decrease of nearly 50% may result from heavy C. osculatum infections, probably amplified by a restricted food availability. The muscle atrophy is likely to reduce the escape reactions of the fish when meeting a foraging seal. In certain regions, where fish and seals are restricted in their migration patterns, such as the semi-enclosed Baltic Sea, the predation may contribute to a severe cod stock depletion. The parasites are zoonotic and represent a human health risk, when consumers ingest insufficiently heat- or freeze-treated infected products. Marked infections of the cod were previously reported during periods with elevated seal populations (late 19th and middle 20th century) and various scenarios for management of risk factors are evaluated in an evolutionary context.

First evidence of grey seal predation on marine mammals in the German Baltic Sea

Grey seal predation on marine mammals has been reported throughout the northern hemisphere except for the Baltic Sea. After the Baltic subspecies (Halichoerus grypus grypus) was on the brink of extinction in the early 1990s, numbers increased steadily during the past three decades from a few thousands to >40,000 in 2020. In recent years, grey seals were observed more frequently in the southern and western Baltic Sea, areas where the subspecies was a rare guest for many decades. Nevertheless, <10% of the Baltic grey seals are counted in the southern Baltic Sea. A standing stranding monitoring programme investigates carcasses of marine mammals washed up in Mecklenburg- Western Pomerania, Germany. In August 2021 a harbour seal (Phoca vitulina) carcass was found with lesions typical for grey seal predation: amongst others the typical “cork-screw”, helical and cut-like lesions with smooth wound margins. The juvenile harbour seal showed 9 of 10 parameters indicating grey seal predation according to van Neer et al., 2021. Earlier suspicious cases in harbour porpoise (Phocoena phocoena) suggest that the presented case may not be an isolated one. Rather, it is a so far rare observation of a behaviour that may become more common with the ongoing recovery of grey seals in the southern Baltic Sea in an area of overlapping habitats with harbour porpoise and harbour seals. In this region harbour seals and harbour porpoise are more abundant than in the Northern Baltic Sea where, as of yet, grey seals are more numerous.

Fitness correlates of blubber oxidative stress and cellular defences in grey seals (Halichoerus grypus): support for the life-history-oxidative stress theory from an animal model of simultaneous lactation and fasting.

Life-history-oxidative stress theory predicts that elevated energy costs during reproduction reduce allocation to defences and increase cellular stress, with fitness consequences, particularly when resources are limited. As capital breeders, grey seals are a natural system in which to test this theory. We investigated oxidative damage (malondialdehyde (MDA) concentration) and cellular defences (relative mRNA abundance of heat shock proteins (Hsps) and redox enzymes (REs)) in blubber of wild female grey seals during the lactation fast (n = 17) and summer foraging (n = 13). Transcript abundance of Hsc70 increased, and Nox4, a pro-oxidant enzyme, decreased throughout lactation. Foraging females had higher mRNA abundance of some Hsps and lower RE transcript abundance and MDA concentrations, suggesting they experienced lower oxidative stress than lactating mothers, which diverted resources into pup rearing at the expense of blubber tissue damage. Lactation duration and maternal mass loss rate were both positively related to pup weaning mass. Pups whose mothers had higher blubber glutathione-S-transferase (GST) expression at early lactation gained mass more slowly. Higher glutathione peroxidase (GPx) and lower catalase (CAT) were associated with longer lactation but reduced maternal transfer efficiency and lower pup weaning mass. Cellular stress, and the ability to mount effective cellular defences, could proscribe lactation strategy in grey seal mothers and thus affect pup survival probability. These data support the life-history-oxidative stress hypothesis in a capitalbreeding mammal and suggest lactation is a period of heightened vulnerability to environmental factors that exacerbate cellular stress. Fitness consequences of stress may thus be accentuated during periods of rapid environmental change.

High‐frequency pingers do not increase catch loss owing to seals in the Baltic Sea

Abstract The Baltic Proper harbour porpoise population is listed as Critically Endangered by IUCN, and only a few hundred animals remain. One of the most serious threats to this population is bycatch in static net fisheries. To minimize bycatch, ICES has proposed that acoustic deterrent devices, pingers, should be used on static nets within the population’s range. However, there have previously been indications that grey seals learn to associate the pinger sounds with the presence of nets with easily accessible prey, and that pinger use therefore can increase the risk of seal depredation in static net fisheries. In recent years, pingers operating at higher frequencies have been made commercially available, the idea being that harbour porpoises will still be able to hear the sound at 50–120 kHz while this will be above or at the limit of seal hearing. This would mean that such high‐frequency pingers would not induce this so‐called dinner‐bell effect. In this study, data were collected from active commercial static net fisheries in the Baltic Proper, using two types of high‐frequency pingers operating at 50–120 and 70 kHz, respectively. Pingers were attached to nets in accordance with manufacturers’ guidelines, and fishers were asked to estimate the catch loss owing to seals in nets with and without pingers. Data were received from 646 deployments made between May 2019 and September 2020. Four generalized mixed effect models were developed with relevant variables. The results suggest using high‐frequency pingers does not increase seal depredation on static nets. It is concluded that pingers could be used as an interim measure to minimize bycatch of the Critically Endangered Baltic Proper harbour porpoise population.

MARINE MAMMALS: MORPHOMETRIC PARAMETERS OF ERYTHROCYTES

Morphological and morphometric parameters of erythrocytes (size, shape and color) were studied in five species of marine mammals. A comparative assessment of oxygen reserves in the blood of the Harp (Pagophilus groenlandicus (Erxleben 1777)) and in Grey seal (Halichoerus grypus (Fabricius 1791)) puppies during adaptations to the aquatic environment, as well as of Bottlenose dolphins during the period of adaptation to captivity conditions is given. Morphometric parameters of red blood cells has been established to vary depending on the age, habitat conditions and phylogenetic position of the animals.

Screening for Influenza and Morbillivirus in Seals and Porpoises in the Baltic and North Sea.

Historically, the seals and harbour porpoises of the Baltic Sea and North Sea have been subjected to hunting, chemical pollutants and repeated mass mortalities, leading to significant population fluctuations. Despite the conservation implications and the zoonotic potential associated with viral disease outbreaks in wildlife, limited information is available on the circulation of viral pathogens in Baltic Sea seals and harbour porpoises. Here, we investigated the presence of the influenza A virus (IAV), the phocine distemper virus (PDV) and the cetacean morbillivirus (CeMV) in tracheal swabs and lung tissue samples from 99 harbour seals, 126 grey seals, 73 ringed seals and 78 harbour porpoises collected in the Baltic Sea and North Sea between 2002-2019. Despite screening 376 marine mammals collected over nearly two decades, we only detected one case of PDV and two cases of IAV linked to the documented viral outbreaks in seals in 2002 and 2014, respectively. Although we find no evidence of PDV and IAV during intermediate years, reports of isolated cases of PDV in North Sea harbour seals and IAV (H5N8) in Baltic and North Sea grey seals suggest introductions of those pathogens within the sampling period. Thus, to aid future monitoring efforts we highlight the need for a standardized and continuous sample collection of swabs, tissue and blood samples across Baltic Sea countries.

First Steps towards the Automated Detection of Underwater Vocalisations of Grey Seals (Halichoerus grypus) in the Blasket Islands, Southwest Ireland

Underwater vocalisations of grey seals (Halichoerus grypus) were recorded by static acoustic monitoring (SM2M, Wildlife Acoustics) in the vicinity of a colony located at White Strand beach on Great Blasket Island, southwest Ireland during the pre-breeding and breeding seasons. Grey seal vocalisations were first classified across nine different categories based on aural and visual characteristics of the spectrograms, providing an acoustic repertoire for grey seals. This classification was further investigated by applying a classification tree analysis, resulting in five of the initial nine groups being selected. Furthermore, a comparison of two common approaches for the detection and extraction of vocalisations from acoustic files was done using the software Raven Pro and PAMGuard. The outputs of this study will present an essential first step towards the development of a protocol for underwater acoustic monitoring of grey seals in Irish waters and elsewhere.

Influence of anthropogenic activities on marine mammal strandings in the estuary and northwestern Gulf of St. Lawrence, Quebec, Canada, 1994–2008

Stranding records have long been used to monitor marine mammal mortalities and to help identify threats to populations. In coastal areas, marinemammals face numerous anthropogenic threats such as marine traffic and commercial fishing. The objective of this study was to investigate marinemammal stranding records from the St. Lawrence Estuary (SLE) and the northwestern Gulf of St. Lawrence (NWGSL), Quebec, Canada from 1994to 2008 for evidence of anthropogenic trauma caused by entanglement in fishing gear, ship collisions and gunshots. Of 1,590 marine mammalstranding records, 12% (n = 192) had evidence of anthropogenic trauma, most incidents being reported during summer when activities such asmarine traffic, most commercial fishing and recreational boating, occurred and a greater number of species were present in the area. These incidentswere classified into five categories (Incidental catch, Ship collision, Severe injury, Gunshot, Other). There were 1,245 mortalities and observationson carcasses suggested that anthropogenic trauma led to the death of 11% (141/1,245) of marine mammals: 14% (87/627) of cetaceans and 9%(54/618) of seals. Mortality of seals due to anthropogenic trauma was low, involving mainly Gunshot for grey (26% or 8/31) and harbour seals(26% or 8/31). Over the study period, marine mammal incidents with evidence of anthropogenic trauma increased significantly, driven by an increasein Incidental catch for two mysticete species, the common minke whale, 42% (39/92) and humpback whale, 13% (12/92) and Other for harbourporpoise 67% (16/24). Ship collision was the most common anthropogenic trauma for fin whales (22% or 8/36) and SLE beluga5 (22% or 8/36).Severe injury was reported for 22% (2/9) of small cetaceans and 78% (7/9) of seals. Evidence from some harbour porpoise stranding records(categorised as Other) suggests illegal hunting, incidental catch, predation or scavenging by grey seals in a marine protected area. The observedincrease in Incidental catch of common minke and humpback whales may be due to: (1) a shift in distribution of these two species into the SLE andNWGSL, possibly related to changes in the ecosystem; (2) changes in fishery practices; and (3) an increase in detection of marine mammal strandings.Anthropogenic trauma affecting marine mammals was documented including some species at risk, such as the harbour porpoise, the St. LawrenceEstuary beluga population, blue and North Atlantic right whales, in the St. Lawrence ecosystem including in a marine protected area. This studydemonstrates the usefulness of stranding records in helping to monitor human-caused mortality in marine mammal populations.