I Grey Seal Distribution and Abundance in North Wales, 2002
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Grey seal distribution and abundance in North Wales, 2002-2003 Westcott, S.M. & Stringell, T.B. Marine Monitoring Report No: 13 This is a report of research commissioned by the Countryside Council for Wales. The Council has a programme of research in scientific and other areas, which supports the development of policies and practical work and helps point the way to new countryside legislation. However, the views and recommendations presented in this report are not necessarily those of the Council and should, therefore, not be attributed to the Countryside Council for Wales. No part of this report may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the Countryside Council for Wales. i Report Number: 13 Publication Date: March 2004 Contract Number: FC-73-02-183 Nominated Officer: T.B. Stringell Title: “Grey seal distribution and abundance in North Wales, 2002-2003” Authors: Westcott, S.M. & Stringell, T.B. Series editors: W.G. Sanderson (monitoring) A. McMath (marine mammals) Restrictions: None Distribution List CCW: T. Stringell CCW HQ x3 M. Baines x1 M.McMath, CCW HQ x1 S. Stansfield, Bardsey Island Bird B.Sanderson CCW HQ x1 Observatory x1 R. Holt, CCW HQ x1 A. Moralee, RSPB South Stack x1 L. Kay, CCW NWA x1 C. Sharpe, Manx Bird Atlas x1 Mike Camplin, CCW, H'FordW x1 T. Johnston, Exploris, Portaferry, NI x1 Blaise Bullimore, CCW H'fordW x1 C. Liret, Oceanopolis, Brest, Brittany x1 Paul Day, CCW NEA x1 R. Penrose, Marine Env Monitoring x1 Neil Smith, CCW NEA x1 Ivor Rees, Uni. Wales, Bangor x1 CCW HQ Library x1 Peter Hope Jones x1 CCW NWA Library x1 David Mawer, IoS Wildlife Trust x1 CCW Cardiff Library x1 T. Nicholson, Cornwall Wildlife Trust x1 CCW Mold Library x1 Marine Awareness North Wales x1 CCW West Area x1 Ian Bullock x1 CCW Skomer MNR x1 Jim Poole x1 Powell Strong x1 Others: David Thomas x1 JNCC Peterborough, Library x1 Chris Richardson, x1 EN Peterborough Library x1 Hilbre Island Observatory x1 R. Covey, EN Cornwall x1 K. Abt, Wadden Sea, Germany x1 SNH Edinburgh, Library x1 R. Witte, Texel, Netherlands x1 National Library Wales x1 UW Cardiff Library x1 National Assembly for Wales Library x1 UW Swansea Library x1 C. Duck, SMRU x1 UW Aberystwyth Library x1 Joe Breen EHS x1 UW Bangor Library x1 PML, Library, Plymouth x1 British Library, Document Supply Centre, S. Westcott x5 Boston Spa x1 Recommended citation for this volume: Westcott, S & Stringell, T.B. 2004. Grey seal distribution and abundance in North Wales, 2002-2003. Bangor, CCW Marine Monitoring Report No: 13. 80pp. ii PREFACE Under the Council Directive 92/43 EEC on the Conservation of natural habitats and of wild fauna and flora (the ‘Habitats Directive’), Member States are required to designate and conserve Special Areas of Conservation (SACs). The purpose of this is to maintain or restore habitats and species listed in Annex I and Annex II to ‘Favourable Conservation Status’. The grey seal Halichoerus grypus Fabricus, is a species listed in Annex II of the Habitats Directive and in Wales they are therefore ‘interest features’ of the Lleyn Peninsula and the Sarns, Pembrokeshire Marine, and Cardigan Bay candidate SACs. The work presented in this report is the second study of its type to investigate the abundance of grey seals as a possible indicator of condition in the ‘Lleyn Peninsula and the Sarns’ SAC. Overall, the work has contributed to the development of methods and procedures for monitoring SACs as well as a dataset that will help to inform how targets could be set for the management of the SAC. Over the last few years many other reviews, surveys, surveillance and monitoring projects have been initiated in Wales for Annex I and II habitats and species. Further CCW reports in this series will be produced as part of this ongoing programme to develop marine monitoring work that underpins the management of conservation sites. RHAGAIR Dan Gyfarwyddeb y Cyngor 92/43 EEC ar warchod cynefinoedd naturiol a fflora a ffawna gwyllt (y ‘Gyfarwyddeb Cynefinoedd’), mae’n ofynnol i aelod-wladwriaethau ddynodi a gwarchod Ardaloedd Cadwraeth Arbennig (ACA). Diben hyn yw cynnal neu adfer cynefinoedd a rhywogaethau a restrir yn Atodiad I ac Atodiad II yr adran sy’n ymwneud ag elfennau sydd â statws cadwraethol ffafriol (‘Favourable Conservation Status’). Fe restrir y morlo llwyd Halichoerus grypus Fabricus yn Atodiad II y Gyfarwyddeb, ac yng Nghymru maent felly yn ‘nodweddion o ddiddordeb’ o fewn ymgeisydd am ACA Pen Llyn a’r Sarnau, ACA Morol Sir Benfro, o fewn ymgeisydd am ac o fewn ymgeisydd am ACA Bae Ceredigion. Yr ail astudiaeth o’i bath gyda’r nod o archwilio faint o forloi llwyd a geir fel arwydd o gyflwr ACA Pen Llyn a’r Sarnau - dyma yw’r gwaith a gyflwynir yn yr adroddiad yma. Yn gyffredinol, mae’r gwaith wedi cyfrannu at ddatblygu dulliau a gweithdrefnau ar gyfer monitro ACA yn ogystal â set ddata a fydd yn ein cynorthwyo i weld sut y gellir gosod targedau yn ymwneud â rheoli ACA. Yn ystod y blynyddoedd diwethaf, mae nifer o adolygiadau, arolygon, a phrosiectau goruchwylio a monitro eraill wedi cael eu rhoi ar y gweill yng Nghymru, sef rhai yn ymwneud â chynefinoedd a rhywogaethau Atodiad I ac Atodiad II. Felly, fe fydd adroddiadau pellach yn perthyn i’r gyfres hon yn cael eu llunio gan y Cyngor Cefn Gwlad yn seiliedig ar ganlyniadau’r rhaglen barhaus yma i ddatblygu gwaith monitro morol sy’n sail i ddulliau rheoli safleoedd cadwraethol. 1 SUMMARY The results of a full census of grey seal distribution and abundance for the period 29 July 2002 to 17 April 2003 are presented here. Occasional winter counts of seals on Ynys Enlli/Bardsey Island are also included. Where possible, female and well-marked male seals were photographed, in order to initiate a detailed study examining the fidelity of seals to North Wales assembly sites. However, in this survey the main purpose of site visits was to count the seals, as far as possible without disturbing them. In North Wales, grey seal distribution at haul-out sites was almost entirely confined to three districts: 1) Ynys Enlli/Bardsey Island and Penrhyn Llyn/Lleyn Peninsula, 2) the West Hoyle Sandbank at the mouth of the Dee Estuary, adjacent to Hilbre Island, 3) a cluster of localities in Ynys Môn/Anglesey: Ynys Arw/North Stack, Ynysoedd y Moelrhoniaid/The Skerries, Trwyn y Gader/Carmel Head, Ynys Dulas and Ynys Seiriol/Puffin Island. The sites used by grey seals in North Wales are usually remote from human access and adjacent to tide races; most consist of rocky island shores or sea cave sites. However, the site where the largest number of seals have been recorded, the West Hoyle Sandbank, is the one exception in that it consists exclusively of fine sand and offers immediate access to strongly tidal water. As in 2001 (Westcott, 2002), counts were highest in summer at the north-east (West Hoyle Sandbank) and west (Ynys Enlli/Bardsey Island) extremes of the seals’ range in North Wales. Highest winter counts were lower than highest summer counts for the region as a whole, and the apparent distribution of the seals also varied between summer and winter. Highest counts for single sites in winter were most often made in the central sector of their range, at the east Ynys Môn/Anglesey islands of Ynys Dulas and Ynys Seiriol/Puffin Island and in the far eastern sector, at West Hoyle Sandbank. Nevertheless, Ynys Enlli/Bardsey Island remained important at this time. At all sites, counts made on consecutive days sometimes showed considerable fluctuation due to weather and sea conditions, or as an aftermath to human disturbance. The number of seals using haul-out sites varied through the year, with the largest number and variety of sites being used during the peak weeks of the breeding season, in September and October. 2 CRYNODEB Yma, cyflwynir canlyniadau cyfrifiad llawn sydd wedi ceisio darganfod dosbarthiad a niferoedd morloi llwyd rhwng 29 Gorffennaf 2002 ac 17 Ebrill 2003. Hefyd, caiff y morloi a gafodd eu cyfrif o dro i dro ar Ynys Enlli yn ystod y gaeaf eu cynnwys. Fe orwedd yr arfordir a’r ynysoedd a arolygwyd rhwng Aberystwyth yn y de ac Aber Afon Dyfrdwy yn y gogledd-ddwyrain, gan gynnwys Ynys Môn. Yng Ngogledd Cymru, roedd dosbarthiad morloi llwyd ar safleoedd a ddefnyddid fel safleoedd gorffwyso wedi eu cyfyngu bron yn gyfan gwbl i dair ardal: 1) Ynys Enlli a Phen Llyn, 2) Banc Tywod West Hoyle yng ngheg Aber Afon Dyfrdwy, ger Ynys Hilbre, 3) clwstwr o lecynnau yn Ynys Môn: Ynys Arw, Ynysoedd y Moelrhoniaid, Trwyn y Gader, Ynys Dulas ac Ynys Seiriol. Fel arfer, mae’r ynysoedd a gaiff eu defnyddio gan forloi llwyd yng Ngogledd Cymru yn bell o fannau y gall y cyhoedd fynd arnynt, ac yn ymyl cerhyntau cryfion. Mae’r rhan fwyaf yn cynnwys glannau creigiog neu ogofâu môr. Fodd bynnag, y safle pwysicaf un, sef Banc Tywod West Hoyle, yw’r unig eithriad o ran ei fod yn cynnwys dim byd ond tywod mân, ac o ran y gellir mynd at ddwr llanwol cryf yn syth o’r safle. Fel yn 2001 (Westcott, 2002), fe welwyd y rhan fwyaf yn ystod yr haf ym mhegynau gogledd-ddwyreiniol (Banc Tywod West Hoyle) a gorllewinol (Ynys Enlli) cwmpas y morloi yng Ngogledd Cymru. Roedd y niferoedd mwyaf a gafodd eu cyfrif yn ystod y gaeaf yn llai na’r niferoedd mwyaf a gafodd eu cyfrif yn ystod yr haf wrth ystyried y rhanbarth yn ei gyfanrwydd, a hefyd fe welwyd gwahaniaeth yn nosbarthiad y morloi rhwng yr haf a’r gaeaf.