Exposing the grey seal as a major predator of harbour porpoises

Leopold, M.F.; Begeman, Lineke; Bleijswijk, Judith van; IJsseldijk, Lonneke L.; Witte, Harry J.; Gröne, Andrea

doi:10.1098/rspb.2014.2429

Cited by 57 publications

(63 citation statements)

References 21 publications

(27 reference statements)

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“…The ruptured eye was most likely caused by the attack. Grey seal attacks have been observed and reported in other locations (Leopold et al 2015, Brownlow et al 2016, although grey seal attacks have not been reported on Cape Cod. If this animal is removed from the calculations, there were no animals reported in the stranding group with eye changes consistent with PUE; thus red or bulging eyes are also considered a strong indicator of PUE.…”

Section: Discussionmentioning

confidence: 98%

Discrimination between bycatch and other causes of cetacean and pinniped stranding

Quirós¹,

Hartwick²,

Rotstein³

et al. 2018

Dis. Aquat. Org.

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The challenge of identifying cause of death in discarded bycaught marine mammals stems from a combination of the non-specific nature of the lesions of drowning, the complex physiologic adaptations unique to breath-holding marine mammals, lack of case histories, and the diverse nature of fishing gear. While no pathognomonic lesions are recognized, signs of acute external entanglement, bulging or reddened eyes, recently ingested gastric contents, pulmonary changes, and decompression-associated gas bubbles have been identified in the condition of peracute underwater entrapment (PUE) syndrome in previous studies of marine mammals. We reviewed the gross necropsy and histopathology reports of 36 cetaceans and pinnipeds including 20 directly observed bycaught and 16 live stranded animals that were euthanized between 2005 and 2011 for lesions consistent with PUE. We identified 5 criteria which present at significantly higher rates in bycaught marine mammals: external signs of acute entanglement, red or bulging eyes, recently ingested gastric contents, multi-organ congestion, and disseminated gas bubbles detected grossly during the necropsy and histologically. In contrast, froth in the trachea or primary bronchi, and lung changes (i.e. wet, heavy, froth, edema, congestion, and hemorrhage) were poor indicators of PUE. This is the first study that provides insight into the different published parameters for PUE in bycatch. For regions frequently confronted by stranded marine mammals with non-specific lesions, this could potentially aid in the investigation and quantification of marine fisheries interactions.

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Section: Discussionmentioning

confidence: 98%

Discrimination between bycatch and other causes of cetacean and pinniped stranding

Quirós¹,

Hartwick²,

Rotstein³

et al. 2018

Dis. Aquat. Org.

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“…Recent reports of grey seals as major predators of harbour porpoises, grey seal pups, and adult harbour seals (Brownlow et al, 2016;Haelters, Kerckhof, Jauniaux, & Degraer, 2012;Leopold et al, 2015;van Neer et al, 2015) have highlighted the potential involvement of grey seal predation in the harbour seal declines. To date, none of these studies has quantified the level of predation.…”

Section: Grey Seal Predationmentioning

confidence: 99%

The status of harbour seals (Phoca vitulina) in the UK

Thompson

Duck

Morris

et al. 2019

Aquatic Conservation

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1. Estimates of population size and trends are essential for effective conservation and management of wildlife populations. For harbour seals (Phoca vitulina), these data are required to fulfil statutory reporting obligations under national and international regulations.2. Aerial survey counts of harbour seals hauled out during their annual moult were used to estimate population sizes and trends at UK, regional (seal management unit, SMU) and local (Special Area of Conservation, SAC) scales.3. Results indicate that the current UK harbour seal population is similar to estimates from the late 1990s, but there were significant declines in some subpopulations and increases in others. 4. Fitted trends suggest that the UK harbour seal population can be divided into three geographically coherent groups: South-east populations (South-East and North-East England SMUs) have shown continuous increases punctuated by phocine distemper virus epidemics in 1988 and 2002; north-east populations (East Scotland, Moray Firth, North Coast and Orkney, and Shetland SMUs) have declined since the late 1990s; north-west populations (West Scotland, Western Isles, and South-West Scotland SMUs) have remained stable or increased. Similar geographical population substructure is evident in recent population genetics results. 5. Trends within SACs generally match SMU trends since 2002. Of the nine SACs designated for harbour seals, four declined (in East Scotland, Moray Firth, and North Coast and Orkney SMUs), four remained stable (in Shetland and West Scotland SMUs), and one increased (in South-East England SMU).6. Large changes in relative abundance have resulted from differences in regional trends. For example, in 1996-1997 the West Scotland and North Coast and Orkney SMUs each held~27% of the Great Britain population but now hold 50% and~4% respectively; in 1980, the South-East England SMU population was~50% that of the Wadden Sea population, but by 2016 it was equivalent to <20% of the Wadden Sea count.

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“…Skin lesions that were likely to have been caused by grey seal predation or fisheries bycatch [29] were excluded from analysis. DNA was extracted from a total of 98 deep-frozen skin lesions of 60 animals, using a QIAamp DNA Mini Kit.…”

mentioning

confidence: 99%

“…They are the most prevalent cetaceans in the North Sea, with an estimated population of 250,000 individuals, of which 85,000 may inhabit Dutch waters [26][27][28]. Since 2008, harbour porpoises that stranded dead, or died shortly after stranding on the Dutch coast, are subjected to postmortem investigation on a regular basis [29].…”

mentioning

confidence: 99%

Identification of a novel gammaherpesvirus associated with (muco)cutaneous lesions in harbour porpoises (Phocoena phocoena)

et al. 2015

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Herpesviruses infect a wide range of vertebrates, including toothed whales of the order Cetacea. One of the smallest toothed whales is the harbour porpoise (Phocoena phocoena), which is widespread in the coastal waters of the northern hemisphere, including the North Sea. Here, we describe the detection and phylogenetic analysis of a novel gammaherpesvirus associated with mucocutaneous and skin lesions in stranded harbour porpoises along the Dutch coast, tentatively designated phocoenid herpesvirus 1 (PhoHV1). Phylogenetically, PhoHV1 forms a monophyletic clade with all other gammaherpesviruses described in toothed whales (Odontoceti) to date, suggesting a common evolutionary origin.

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Exposing the grey seal as a major predator of harbour porpoises

Cited by 57 publications

References 21 publications

Discrimination between bycatch and other causes of cetacean and pinniped stranding

Discrimination between bycatch and other causes of cetacean and pinniped stranding

The status of harbour seals (Phoca vitulina) in the UK

Identification of a novel gammaherpesvirus associated with (muco)cutaneous lesions in harbour porpoises (Phocoena phocoena)

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