Grey Seal Predation in Cod Gillnet Fisheries in the Central Baltic Sea

Koningson, S; Lunneryd, S-G; Stridh, H; Sundqvist, Frida

doi:10.2960/j.v42.m654

Cited by 47 publications

(26 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Body size dimorphism has been suggested as a factor shaping the differences in diet of males and females of this species (Beck et al, 2007). Grey seals sometimes take the easiest prey available such as fish from static gear and from fish farms (Matthiopoulos et al, 2004;Quick et al, 2004;Königson et al, 2009). Although grey seals are opportunistic feeders, harbour porpoises-to our knowledge-only have been reported as part of their diet on one occasion, with a large grey seal bull "handling" and apparently scavenging on a freshly dead harbour porpoise carcass off the mainland coast of Noord-Holland, The Netherlands, in February 2011 (Camphuysen & Siemensma, 2011).…”

Section: Predation or Competitive Interaction?mentioning

confidence: 99%

The Grey Seal (Halichoerus grypus) as a Predator of Harbour Porpoises (Phocoena phocoena)?

Haelters¹

2012

Aquat Mamm

View full text Add to dashboard Cite

In September 2011, two harbour porpoises (Phocoena phocoena) presenting extensive traumatic lesions washed ashore in Belgium. Similar lesions, with large parts of skin and blubber missing, had not been recorded before on harbour porpoises in Belgium but were recently observed in a number of cases in neighbouring countries. We compared the lesions with the mouth and teeth structure of possible predators. The circumstances of the strandings, the observations during the necropsies, and the results of seal skull investigations pointed towards seals, presumably grey seals (Halichoerus grypus), as the prime suspects for having caused the death of both harbour porpoises. Although purely aggressive behaviour cannot be completely excluded, predation is considered most likely as part of the skin and blubber tissue of the harbour porpoises was missing. The grey seal is an opportunistic predator, feeding on a variety of fish and cephalopods, and occasionally even on crustaceans and seabirds, but predation on harbour porpoises, or any other marine mammal, had to our knowledge never been described. This finding might shed a new light on the cause of death of some of the other mutilated harbour porpoises recently stranded on southern North Sea beaches, and it presents a case of a change in the feeding strategy of a top predator.

show abstract

Section: Predation or Competitive Interaction?mentioning

confidence: 99%

The Grey Seal (Halichoerus grypus) as a Predator of Harbour Porpoises (Phocoena phocoena)?

Haelters¹

2012

Aquat Mamm

View full text Add to dashboard Cite

show abstract

“…; Königson et al . ; Rafferty et al . ), among other pinnipeds (Wickens ), and sea otters (Hatfield et al .…”

Section: Reviewmentioning

confidence: 99%

Mitigating unaccounted fishing mortality from gillnets and traps

2013

View full text Add to dashboard Cite

Gillnets and traps often are considered to have fewer holistic environmental impacts than active fishing gears. However, in addition to the targeted catches, gillnets and traps still cause unwanted mortalities due to (i) discarding, (ii) ghost fishing of derelict gear, (iii) depredation, (iv) escaping or dropping out of gear, (v) habitat damage, and potentially (vi) avoiding gear and predation and (vii) infection of injuries sustained from most of the above. Population‐level concerns associated with such ‘unaccounted fishing mortalities’ from gillnets and traps have been sufficient to warrant numerous attempts at mitigation. In this article, we reviewed relevant research efforts, locating 130 studies in the primary literature that concomitantly quantified mortalities and their resolution through technical modifications, with the division of effort indicating ongoing concerns. Most studies (85) have focused on discard mortality, followed by ghost‐fishing (24), depredation (10) and escape (8) mortalities. The remaining components have been poorly studied (3). All problematic mortality components are affected by key biological (e.g. species), technical (e.g. fishing mechanisms) and/or environmental (e.g. temperature) factors. We propose that these key factors should be considered as part of a strategy to reduce impacts of these gears by first assessing modifications within and then beyond conventional configurations, followed by changes to operational and handling practices. Justification for this three‐tiered approach is based not only on the potential for cumulative reduction benefits, but also on the likely ease of adoption, legislation and compliance.

show abstract

“…Throughout the region, this has led to renewed conflicts with fisheries (Königson et al . , ; Gardmark et al . ) and debates over possible counter‐measures, such as hunting and culling (Naturvårdsverket ; DME ).…”

Section: Introductionmentioning

confidence: 99%

Shift of grey seal subspecies boundaries in response to climate, culling and conservation

et al. 2016

View full text Add to dashboard Cite

Identifying the processes that drive changes in the abundance and distribution of natural populations is a central theme in ecology and evolution. Many species of marine mammals have experienced dramatic changes in abundance and distribution due to climatic fluctuations and anthropogenic impacts. However, thanks to conservation efforts, some of these species have shown remarkable population recovery and are now recolonizing their former ranges. Here, we use zooarchaeological, demographic and genetic data to examine processes of colonization, local extinction and recolonization of the two northern European grey seal subspecies inhabiting the Baltic Sea and North Sea. The zooarchaeological and genetic data suggest that the two subspecies diverged shortly after the formation of the Baltic Sea approximately 4200 years bp, probably through a gradual shift to different breeding habitats and phenologies. By comparing genetic data from 19th century pre-extinction material with that from seals currently recolonizing their past range, we observed a marked spatiotemporal shift in subspecies boundaries, with increasing encroachment of North Sea seals on areas previously occupied by the Baltic Sea subspecies. Further, both demographic and genetic data indicate that the two subspecies have begun to overlap geographically and are hybridizing in a narrow contact zone. Our findings provide new insights into the processes of colonization, extinction and recolonization and have important implications for the management of grey seals across northern Europe.

show abstract

Grey Seal Predation in Cod Gillnet Fisheries in the Central Baltic Sea

Cited by 47 publications

References 6 publications

The Grey Seal (Halichoerus grypus) as a Predator of Harbour Porpoises (Phocoena phocoena)?

The Grey Seal (Halichoerus grypus) as a Predator of Harbour Porpoises (Phocoena phocoena)?

Mitigating unaccounted fishing mortality from gillnets and traps

Shift of grey seal subspecies boundaries in response to climate, culling and conservation

Contact Info

Product

Resources

About