Sympatric seals, satellite tracking and protected areas: habitat-based distribution estimates for conservation and management

Matt I. Carter* (Corresponding Author), Lars Boehme, Michelle A. Cronin, Callan Duck, W. James Grecian, Gordon D. Hastie, Mark J. Jessopp, Jason Matthiopoulos, Bernie J. McConnell, Chris D. Morris, Simon E. W. Moss, Dave Thompson, Paul Thompson, Debbie J. F. Russell* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)
6 Downloads (Pure)


Marine predator populations are crucial to the structure and functioning of ecosystems. Like many predator taxa, pinnipeds face an increasingly complex array of natural and anthropogenic threats. Understanding the relationship between at-sea processes and trends in abundance at land-based monitoring sites requires robust estimates of at-sea distribution, often on multi-region scales. Such an understanding is critical for effective conservation management, but estimates are often limited in spatial extent by spatial coverage of animal-borne tracking data. Grey (Halichoerus grypus) and harbour seals (Phoca vitulina) are sympatric predators in North Atlantic shelf seas. The United Kingdom (UK) and Ireland represents an important population centre for both species, and Special Areas of Conservation (SACs) are designated for their monitoring and protection. Here we use an extensive high-resolution GPS tracking dataset, unprecedented in both size (114 grey and 239 harbour seals) and spatial coverage, to model habitat preference and generate at-sea distribution estimates for the entire UK and Ireland populations of both species. We found regional differences in environmental drivers of distribution for both species which likely relate to regional variation in diet and population trends. Moreover, we provide SAC-specific estimates of at-sea distribution for use in marine spatial planning, demonstrating that hotspots of at-sea density in UK and Ireland-wide maps cannot always be apportioned to the nearest SAC. We show that for grey seals, colonial capital breeders, there is a mismatch between SACs (where impacts are likely to be detected) and areas where impacts are most likely to occur (at sea). We highlight an urgent need for further research to elucidate the links between at-sea distribution during the foraging season and population trends observed in SACs. More generally, we highlight that the potential for such a disconnect needs to be considered when designating and managing protected sites, particularly for species that aggregate to breed and exhibit partial migration (e.g. grey seals), or spatial variation in migration strategies. We demonstrate the use of strategic tracking efforts to predict distribution across multiple regions, but caution that such efforts should be mindful of the potential for differences in species-environment relationships despite similar accessible habitats.
Original languageEnglish
Article number875869
Number of pages18
JournalFrontiers in Marine Science
Early online date20 Jun 2022
Publication statusPublished - 20 Jun 2022

Bibliographical note

Analysis was funded by the UK Government Department for Business, Energy and Industrial Strategy (BEIS; OESEA-16-76/OESEA-17-78) with support from the Natural Environment Research Council (NERC; INSITE Phase II NE/T010614/1
EcoSTAR), EU INTERREG (MarPAMM), and the Scottish Government (MMSS/002/15). DJFR’s contribution was funded by NERC National Capability Funding (NE/R015007/1). WJG was
supported by INSITE Phase I (MAPS). Telemetry tags and their deployment were funded in the UK by BEIS (and previous incarnations), NERC, Marine Scotland, Scottish Government, NatureScot, SMRU, SMRU Instrumentation Group, Marine
Current Turbines, Ørsted, the Met Office, the Zoological Society of London (ZSL), the Crown Estate, Highlands & Islands Enterprise, Moray Firth Renewables Limited (MORL), Beatrice Offshore Windfarm Limited (BOWL), SITA Trust, BBC Wildlife Fund and the Hampshire & Isle of Wight Wildlife Trust. Tags and their deployment in Ireland were funded by Inland Fisheries Ireland, the Department of Communications, Marine and Natural Resources, the Higher Education Authority of Ireland, the National Geographic
Society, the Department of Agriculture, Food and the Marine, and the National Parks and Wildlife Service. UK aerial surveys conducted by SMRU were funded by NERC (NE/R015007/1),
NatureScot, the Department for Agriculture, Environment and Rural Affairs (Northern Ireland), Marine Current Turbines, Marine Scotland, Natural England, and Scottish Power. Aerial
surveys in Ireland were funded by the Department for Tourism, Culture, Arts, Gaeltacht, Sport and Media.
We thank Matt Bivins (SMRU), Phil Lovell (SMRU
Instrumentation Group), and the many people who were involved in or facilitated fieldwork, including landowners and reserve managers. We are grateful to Dr Carol Sparling (SMRU),
Dr Sophie Smout (SMRU) and Prof. Philip Hammond (SMRU) for useful discussions. We thank Hartley Anderson Ltd. for their support and guidance. This study is dedicated to the memory of Dr Bernie McConnell; a legend in the field of biologging and seal ecology who taught us all so much. Unfortunately, Bernie did not get to read the final draft of this manuscript, but we are grateful for his valuable input throughout the study


  • Animal-borne telemetry
  • Marine Spatial Planning (MSP)
  • Marine vertebrate predators
  • Regional habitat preference
  • Partial migration
  • place-based conservation
  • Special Area of Conservation (SAC)
  • Use-availability


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