Evidence Review to Support the Identification of Potential Conservation Measures for Selected Species of Seabirds
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EVIDENCE REVIEW TO SUPPORT THE IDENTIFICATION OF POTENTIAL CONSERVATION MEASURES FOR SELECTED SPECIES OF SEABIRDS Prepared by: Professor Bob Furness, David MacArthur, Dr Mark Trinder & Kirsty MacArthur Date: 30 June 2013 Tel: 0141 342 5404 Web: www.macarthurgreen.com Office: 95 South Woodside Road |Glasgow | G20 6NT Evidence Review Document Quality Record. Version Status Authorised by Date 1.0 Draft DMacArthur 30/04/2013 2.0 Final KMacArthur 30/06/2013 3.0 Minor DMacArthur 20/09/2013 revisions after peer review 4.0 Final version DMacArthur 14/10/2013 Disclaimer: The content of this report does not necessarily reflect the views of Defra, nor is Defra liable for the accuracy of information provided, or responsible for any use of the report’s content i | P a g e Evidence Review CONTENTS LIST OF TABLES & FIGURES .......................................................................................................... VI ACRONYMS ............................................................................................................................... VIII EXECUTIVE SUMMARY ................................................................................................................ IX 1. INTRODUCTION .................................................................................................................... 1 2. AIMS AND OBJECTIVES ......................................................................................................... 1 3. REPORT STRUCTURE ............................................................................................................. 2 4. GENERAL REVIEW OF FACTORS AFFECTING SEABIRD POPULATION SIZES WITH PARTICULAR REFERENCE TO THE BREEDING SEABIRDS OF THE BRITISH ISLES ..................................................... 3 4.1 INTRODUCTION .......................................................................................................................................... 3 4.2 EXPLOITATION AND PERSECUTION .................................................................................................................. 5 4.3 FOOD SUPPLY ............................................................................................................................................ 5 4.4 FISHERIES ................................................................................................................................................. 7 4.4.1 Fishery bycatch ................................................................................................................................. 8 4.4.2 Fishing of pelagic prey fish stocks ..................................................................................................... 8 4.4.3 Discards and offal ............................................................................................................................. 9 4.5 CLIMATE CHANGE ..................................................................................................................................... 10 4.6 PREDATION ............................................................................................................................................. 12 4.7 DISTURBANCE .......................................................................................................................................... 16 4.8 PARASITES AND DISEASE ............................................................................................................................ 16 4.9 OIL POLLUTION ........................................................................................................................................ 17 4.10 PERSISTENT ORGANIC POLLUTANTS AND HEAVY METALS .................................................................................. 17 4.11 PLASTICS ................................................................................................................................................ 18 4.12 OFFSHORE WIND FARMS ............................................................................................................................ 19 4.13 WAVE AND TIDAL ARRAYS .......................................................................................................................... 20 4.14 CONCLUSIONS ......................................................................................................................................... 21 5. A POPULATION MODELLING APPROACH TO ASSESSING THE RELATIVE EFFICACY OF MANAGEMENT ACTION AFFECTING SURVIVAL VERSUS REPRODUCTIVE OUTPUT ......................... 21 5.1 INTRODUCTION ........................................................................................................................................ 21 5.2 METHODS .............................................................................................................................................. 22 5.3 RESULTS ................................................................................................................................................. 24 6. LIFE HISTORY CONSIDERATIONS AND THEIR IMPLICATIONS FOR MANAGEMENT .................. 25 7. EVIDENCE REVIEW OF POTENTIAL MANAGEMENT OPTIONS FOR RED-THROATED DIVER ...... 27 7.1 RED-THROATED DIVER ECOLOGY .................................................................................................................. 27 7.1.1 The species in the British Isles ......................................................................................................... 27 7.1.2 Present, and likely future trends ..................................................................................................... 27 7.1.3 Factors affecting survival rates ....................................................................................................... 28 7.1.4 Breeding success in the British Isles ................................................................................................ 28 7.2 MANAGEMENT OPTIONS............................................................................................................................ 30 7.2.1 Provision of nest platforms on breeding lochs .................................................................................... 30 7.2.2 Closure of sandeel and sprat fishing close to wintering area SPAs ..................................................... 32 7.2.3 Closure of sandeel and sprat fishing close to breeding area SPAs or all UK waters ............................ 32 8. EVIDENCE REVIEW OF POTENTIAL MANAGEMENT FOR MANX SHEARWATER ....................... 33 8.1 MANX SHEARWATER ECOLOGY ........................................................................................................... 33 8.1.1 The species in the British Isles ......................................................................................................... 33 8.1.2 Present, and likely future trends ..................................................................................................... 33 8.1.3 Factors affecting survival rates ....................................................................................................... 34 ii | P a g e Evidence Review 8.1.4 Breeding success in the British Isles ................................................................................................ 34 8.2 MANAGEMENT OPTIONS............................................................................................................................ 36 8.2.1 Eradication of alien mammals from islands with Manx shearwater colonies .................................... 37 8.2.2 Exclusion of large gulls from Manx shearwater colonies .................................................................... 39 Great black-backed gulls were identified as ................................................................................................ 39 8.2.3 Closure of sandeel and sprat fishing close to breeding area SPAs or all UK waters ............................ 40 9. EVIDENCE REVIEW OF POTENTIAL MANAGEMENT FOR NORTHERN GANNET ........................ 41 9.1 NORTHERN GANNET ECOLOGY .................................................................................................................... 41 9.1.1 The species in the British Isles ......................................................................................................... 41 9.1.2 Present, and likely future trends ..................................................................................................... 41 9.1.3 Factors affecting survival rates ....................................................................................................... 42 9.1.4 Breeding success in the British Isles ................................................................................................ 42 9.2 MANAGEMENT OPTIONS............................................................................................................................ 44 9.2.1 Management to increase survival rates ......................................................................................... 44 9.2.2 End harvest of gannet chicks on Sula Sgeir ..................................................................................... 44 9.2.3 Encourage establishment of new colonies ...................................................................................... 45 9.2.4 Reduce bycatch in fisheries ............................................................................................................. 45 10. EVIDENCE REVIEW OF POTENTIAL MANAGEMENT FOR ARCTIC