Site use and connectivity of female grey seals (Halichoerus grypus) around Wales

Izzy Langley,Charlie Lindenbaum,Stephen Westcott,Oliver O’Cadhla,Rebecca M Boys,Edward M Stubbings,Lisa Morgan,Mick Baines,Holly Self,Dave Boyle,Patrick P Pomeroy,Kate Lock,Lex Hiby,Ceri W Morris,Tobias Rosas Da Costa Oliver,Sarah Perry,Thomas B Stringell,Birgitta I Büche,Powell Strong

doi:10.1007/s00227-020-03697-8

Izzy Langley, Charlie Lindenbaum + Show 17 more

Open Access

https://doi.org/10.1007/s00227-020-03697-8

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Abstract

Grey seals (Halichoerus grypus) are a qualifying feature of three special areas of conservation (SACs) in Wales, yet relatively little is known of their site use along this coastline. Since 1992, many individuals and organisations have contributed to a grey seal photographic identification database held by Natural Resources Wales, which is one of the largest and oldest of its kind, providing key information from grey seal haul-out sites around the Celtic and Irish Seas. Here, we investigated spatial connectivity of haul-out sites and fidelity of adult females to breeding sites. The minimum number of adult female grey seals using the area between 1992 and 2016 was 2688. Individual capture histories and relative spatial transition probabilities (Pij) between pairs of location groups were calculated. Adjacent locations were highly connected (e.g. Lleyn Peninsula and Bardsey, Pij = 0.7) but connections spanned the entire region, up to 230 km apart (e.g. Skomer and Dee Estuary, Pij = 0.004). Resights were recorded within SACs (e.g. Lleyn Peninsula and Bardsey [Lleyn Peninsula and the Sarnau SAC], Pij = 0.7), between SACs (e.g. Bardsey and Skomer [Pembrokeshire Marine], Pij = 0.03), between SACs and non-designated areas (e.g. Skerries and Bardsey, Pij = 0.09) and between sites outside any protected area (e.g. Dee Estuary and Anglesey, Pij = 0.5). While inter-annual fidelity to breeding sites was high (Pij = 0.82–1), individual female grey seals moved throughout the region. This evidence of extensive site use beyond protected areas is important for the management and conservation of grey seals around Wales.

Highlights

Population studies of long-lived animals must cover a substantial part of their lifespan, providing information on population size, status and vital rates, along with individual behaviour, to best inform management (Pianka 1970).Natural Resources Wales, Martin’s Haven, Pembrokeshire, Wales, UKCardigan Bay Marine Wildlife Centre, The Wildlife Trust of South and West Wales, New Quay, Wales, UKThe Wildlife Trust of South and West Wales, Skomer Island, C/O Lockley Lodge, Martin’s Haven, Pembrokeshire, UKPembrokeshire College, Haverfordwest, Pembrokeshire, Wales, UKDyfed Wildlife Trust ( The Wildlife Trust of South and West Wales), Bridgend, Wales, UK Page 2 of 15Marine Biology (2020) 167:86A significant challenge of marine spatial planning requires an understanding of how marine animals use their habitat and which areas are important throughout the animals’ life history
We estimate a minimum of 2688 individual adult female grey seals used haul-out sites around the Welsh coastline between 1992 and 2016
With the recapture interval set to days, the highest number of occasions when recaptures were recorded at surveyed sites between 1992 and 2016 was 28—an individual seal was first recorded at the Lleyn Peninsula and subsequently recaptured at Anglesey, with 15 different capture records in 2010

Summary

Introduction

Population studies of long-lived animals must cover a substantial part of their lifespan, providing information on population size, status and vital rates, along with individual behaviour, to best inform management (Pianka 1970).Natural Resources Wales, Martin’s Haven, Pembrokeshire, Wales, UKCardigan Bay Marine Wildlife Centre, The Wildlife Trust of South and West Wales, New Quay, Wales, UKThe Wildlife Trust of South and West Wales, Skomer Island, C/O Lockley Lodge, Martin’s Haven, Pembrokeshire, UKPembrokeshire College, Haverfordwest, Pembrokeshire, Wales, UKDyfed Wildlife Trust ( The Wildlife Trust of South and West Wales), Bridgend, Wales, UK Page 2 of 15Marine Biology (2020) 167:86A significant challenge of marine spatial planning requires an understanding of how marine animals use their habitat and which areas are important throughout the animals’ life history. The Wildlife Trust of South and West Wales, Skomer Island, C/O Lockley Lodge, Martin’s Haven, Pembrokeshire, UK. In the UK, seals at well-studied colonies have high breeding site fidelity (Pomeroy et al 1994, 2000) with a clockwise cline in mean birth date (from August in SW England to December in the southern North Sea; SCOS 2018). Grey seals haul-out onto land to rest, digest, breed and moult, and the number of animals at haul-out sites vary throughout the year (Baines et al 1995; Sparling et al 2007; Russell et al 2015). Studies of movements of grey seals on the UK’s east coast found that they spent 32% of their time travelling between haul-out sites (Thompson et al 1991) and moved between haul-out sites up to 2,100 km apart (McConnell et al 1999)

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