Fifth otter survey of England 2009 - 2010 Technical report We are The Environment Agency. It's our job to look after your environment and make it a better place – for you, and for future generations. Your environment is the air you breathe, the water you drink and the ground you walk on. Working with business, Government and society as a whole, we are making your environment cleaner and healthier. The Environment Agency. Out there, making your environment a better place. This document has been produced in partnership with: Author - Andrew Crawford (Environment Published by: Agency) Environment Agency Project Manager - Graham Scholey Rio House (Environment Agency) Waterside Drive, Aztec West Main survey contractors - Elizabeth Almondsbury, Bristol BS32 4UD Andrews, Hilary Marshall, John Martin, Tel: 0870 8506506 Email: enquiries@environment- Robin Roper, Andy Rothwell, Mark Satinet agency.gov.uk Alternate squares surveyors - see www.environment-agency.gov.uk acknowledgements © Environment Agency Further copies of this report are available from our publications catalogue: All rights reserved. This document may be http://publications.environment- reproduced with agency.gov.uk or our National Customer prior permission of Contact Centre: T: 08708 506506 the Environment Agency. E: [email protected]. - 2 - Summary The fifth national otter survey of England has for the first time achieved comprehensive coverage of the whole country. Two field survey techniques were used in parallel – full surveys for sites investigated in previous national surveys (the main survey), and spot- checks for all the alternate 50km squares not covered in the previous surveys. The main survey was carried out between July 2009 and March 2010. Six highly experienced otter surveyors examined 3327 sites across the country using thirty-eight 50 x 50 km squares (the north-west and south-east quarters of each 100km square) as a sampling grid. Footprints and droppings (spraints) represent the most distinctive signs of otter and their presence within the standard 600m survey length of river represented a ‘positive’ site record. Signs of otters were recorded at 1874 (56%) of sites in the main survey. In addition, the alternate squares spot-checks undertaken within the same time frame proved otter presence in 553 of the 718 10km squares surveyed. Direct comparison of positive records from 2940 sites used in all five national surveys reveals the recovery of otters from virtual extinction in most of England during the early 1970s. Positive site records increased from 5.8 per cent in 1977-79, to 9.6 per cent in 1984-86; 23.4 per cent in 1991-94; 36.3 per cent in 2000-02 and 58.8 per cent in 2009-10. Recovery has continued in all but the very south-east where no signs were found in Kent or most of Sussex. Re-colonisation from strongholds in south-west and northern England and Wales has now been consolidated across much of the country and continues to drive recovery. Since 2000-02 there has been a major link-up across several river catchments. For example, there is no longer a gap in otter distribution between the south-west, south Wales, lower Wye and Severn and upper Thames. Similarly, there is now a link between populations in East Anglia, the River Trent catchment, Yorkshire and the traditional Northumbria stronghold. The pattern of recovery differs at a regional scale, with Thames showing the biggest increase in positive signs since 2000-02. In South-West Region and the River Wye catchments otter populations have probably reached a level approximating to carrying capacity, with those in Northumbria, Cumbria, Wessex and the upper Severn close to that. Elsewhere, further recovery and consolidation will take more time. Recovery has been in response to three main factors, the ban on pesticides that caused extinction of otters from many parts of England in the 1960s and early 1970s, legal protection for the otter since 1978, and the significant improvement in water quality in previously fishless rivers since the 1970s. Re-introduction programmes of captive bred and re-habilitated otters in certain parts of the country are likely to have speeded up the recovery locally in East Anglia, Yorkshire and the upper Thames. However the majority of the recovery has been the result of natural expansion from the remnant populations. The prospects are for full recovery across England probably within the next two decades or so. This represents a major success story for pollution control, as well as investment by the water industry and efforts by landowners and river managers to improve river and riparian habitat. Tracking the otter’s recovery has demonstrated the benefits of long-term monitoring and the use of this iconic species to raise awareness of pollution problems and the benefits of action to improve the environment. - 3 - The revised (2006) Biodiversity Action Plan (BAP) target for otters in England was for at least 997 10km squares to show signs of otter occupation by 2010 and for 1084 10km squares to show signs of otter occupation by 2015. The 2015 target has already been exceeded, with 1085 squares showing signs of occupation in either the main survey or alternate squares spot-checks. The recovery has thus proceeded at a slightly faster rate than expected in 2006 but is still close to, or slightly below the expected recovery curve published by Strachan and Jefferies (1996). The continued recovery has brought an increase in the number of reported otter road kills. These have nearly doubled from 313 reported deaths on the road during the four year period 2002 to 2005 to 600 in the four year period 2006 to 2009. These and other dead otters reported to the Environment Agency form the basis of the programme of otter post mortem and tissue analysis undertaken with Cardiff University and the Centre for Ecology and Hydrology. This work has shown that the current suite of chemicals monitored in otter tissue has declined to levels where they should not cause significant pathology. One of the results of the recovery of otter populations has been increased concern about predation, particularly on still water fisheries and on specimen fish. This creates a challenge to all those involved in river, wetland and fishery management to ensure that the successful return of our top freshwater predator is not seen as a long term problem for fisheries but as a symbol of a healthy ecosystem. - 4 - Contents Introduction 6 Methods 8 Overall results for England 11 Map 1 Alternate 50km squares used in survey 12 Table 1 results for 2009-10 survey by region and comparison with other surveys 13 Table 2 Summary of Results by 50km square 14 Fig 1 Change in percentage of positive sites by region 16 Maps 2-6 Percentage positive by region (1977-79 to 2009-10) 17 - 21 Maps 7-11 Positive/new positive (1977-79 to 2009-10) 22 - 26 Map 12 Otter distribution by 10km square 27 Map 13 Catchment (Leap) areas in England 28 The regional reports introduction 29 (Regional reports each with maps) North West 30 Northumbrian 36 Yorkshire 40 Dee 45 Severn 48 Trent 52 Wye 57 Anglian 60 Thames 67 South West 72 Wessex 79 Southern 85 Mink 90 Map 26 Mink distribution 2000-02 93 Map 27 Mink distribution 2009-10 94 Map 28 Mink distribution by 10km square 95 Otter sightings - PTES 96 Discussion 97 Otters and fisheries 108 Priorities for future action 112 Conclusions 114 Funding 116 Acknowledgements 117 References 120 Appendix 1 Typical site map 124 Appendix 2 Section of main survey spreadsheet 125 Appendix 3 Alternate squares recording sheet 126 - 5 - 1.0 Introduction The Eurasian or European otter (Lutra lutra) is widely recognised as an emblem for nature conservation in the UK because it is a top predator and important biological indicator of the health of our rivers and wetlands. Monitoring the status of the otter therefore gives us a valuable measure of the state of our water and wetland ecosystems. In England it is a largely nocturnal animal and is rarely observed in the wild. It is however possible to detect its presence by searching for faeces (spraints) and footprints. The otter suffered serious declines throughout most of its European range, and by the mid 1970s the UK otter population had been reduced to a point where they only existed in Scotland, parts of Wales and the West Country with a few remnant populations in other parts of England. Conservation action for the otter in Britain has a long history with many players fulfilling different roles. The Environment Agency is now the contact point for otter conservation under the UK Biodiversity Action Plan (UK BAP) and is a lead partner with the Wildlife Trusts in implementing the Otter Species Action Plan. The Otter BAP Steering Group also includes representatives from the statutory nature conservation bodies – Natural England (NE), Countryside Council for Wales (CCW), Scottish Natural Heritage (SNH), the Northern Ireland Environment Agency and the Joint Nature Conservation Committee (JNCC) as well as Water UK (umbrella body for the water companies), the Scottish Environment Protection Agency (SEPA), the Department of Agriculture (N.I.) and the Wildlife Trusts. The first national otter survey of England was carried out in 1977-79 (Lenton et al., 1980). It provided a baseline for the distribution of otters and, together with surveys in Wales, Scotland and Ireland (Crawford et al., 1979; Green & Green, 1980; Chapman & Chapman, 1982), was undertaken in response to growing concern for the status of the otter in Britain (O’Connor et al., 1977). Of the 2,940 sites surveyed in England in 1977-79, only 170 (5.8%) showed evidence of otters. This confirmed the results of the analysis of hunting records (Anon, 1969, 1974; Chanin & Jefferies, 1978), the impression of many naturalists (Walker, 1970, Howes, 1976, Lloyd, 1962) and the results of a volunteer survey by the Mammal Society (O’Connor et al., 1977) that there had been a major decline in otter distribution.