Solent Seal Tagging Project Summary Report

Home , Chichester Harbour, Langstone Harbour, Portsmouth Harbour, River Test, Selsey Bill, The Solent

Wildlife Trusts’ South East Marine Programme March 2010

Preface and copyright

This report was written by The Wildlife Trusts’ South East Marine Programme, supported by Hampshire and Isle of Wight Wildlife Trust and Chichester Harbour Conservancy, as part of the Solent Seal Tagging Project. The ownership and copyright of any matter arising from this project and this report is held by Hampshire and Isle of Wight Wildlife Trust and Chichester Harbour Conservancy. No copies of this inventory may be made without express permission of Hampshire and Isle of Wight Wildlife Trust or Chichester Harbour Conservancy.

This report is disseminated as a PDF document and is available electronically from Hampshire and Isle of Wight Wildlife Trust or Chichester Harbour Conservancy. The seal tag data contained within this report is held as Google Earth, Access Database and MapInfo files at Hampshire and Isle of Wight Wildlife Trust and Chichester Harbour Conservancy. Please consult Hampshire and Isle of Wight Wildlife Trust or Chichester Harbour Conservancy for further information on raw data availability.

This report is a summary of the data collected so far, as the data is further analysed updates will be issued.

This report should be referred to as: Chesworth, J. C., Leggett, V. L. and Rowsell, E. S. 2010. Solent Seal Tagging Project Summary Report. Wildlife Trusts’ South East Marine Programme, Hampshire and Isle of Wight Wildlife Trust, Hampshire.

Wildlife Trusts’ South East Marine Programme Chichester Harbour Conservancy C/O Hampshire and Isle of Wight Wildlife Trust Harbour Office Beechcroft House Itchenor Vicarage Lane Chichester Curdridge West Sussex PO20 7AW Hampshire SO32 2DP Tel: 01243 512301 Tel: 01489 7744400

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 ii Acknowledgements

The Wildlife Trusts’ South East Marine Programme would like to thank the funding organisations who enabled this project to take place: Sita Trust, Natural England Countdown 2010 Biodiversity Action Fund, Chichester Harbour Conservancy, Friends of Chichester Harbour, Hampshire and Isle of Wight Wildlife Trust, Environment Agency and Solent Forum.

The Wildlife Trusts’ South East Marine Programme would also like to thank the following, who have kindly provided data, advice, support and time to this project and the production of this report: The Sea Mammal Research Unit, All those at Chichester Harbour Conservancy, Langstone Harbour Board, Portsmouth Outdoor Education Centre, Sussex Sea Fisheries Committee, Queens University Belfast, Salacia Marine, Steven Savage, Mark Heighes, Chas Spradbery, Chris Bashall, Philip Hoare, River Hamble Harbour Office and Colin Froud.

We are also grateful to all those members of the public who have contributed to our data through sending in sightings and photographs of seals.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 iii Executive Summary

The Solent Seal Tagging project was initiated in December 2008 by The Wildlife Trusts’ South East Marine Programme and Chichester Harbour Conservancy. The aim was to learn more about the Solent harbour seal population with a view to improving its conservation. The project utilised various techniques to survey and monitor the seal populations including visual counts at haul-outs, a public sightings scheme, photo- identification and telemetry.

Key findings include: • Number of harbour seals currently estimated at 23-25, with 18 being the most recorded at any one time. Being a small population makes them more vulnerable to impacts. • Only two significant haul-out sites exist, one in Langstone Harbour and one in Chichester Harbour. • Both haul-out sites are used on a more or less daily basis but Chichester Harbour is used by more seals. • The seals display often individual foraging behaviour and are faithful to their preferred foraging sites. • The seals predominately forage in the Eastern Solent, between Southampton and Selsey Bill, often in the harbours, and regularly cross to the Isle of Wight. • Seal foraging activity can change between seasons. • Seal foraging takes place in a variety of habitat types and can focus on discrete seabed features such as rocky reefs and underwater structures.

The findings presented in this report are a summary and further data analysis is being carried out.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 iv Contents

1. Report aims and objectives 1 2. Introduction to UK seals 2 2.1 Species types 2 2.2 Haul out behaviour and habitat preferences 4 2.3 Feeding behaviour 5 2.4 Breeding behaviour 6 2.5 Distribution and population trends 7 2.6 Conservation measures 9 2.7 Seal population counts and monitoring methods 12 3. Solent Seal Tagging Project 16 3.1 Introduction 16 3.1.1 Project background 16 3.1.2 Project aims 17 3.1.3 Site characterisation 17 3.1.4 History of the Solent seal population 19 3.2 Methodology 20 3.2.1 Visual surveys 20 3.2.2 Public sightings 21 3.2.3 Photo Identification 21 3.2.4 Telemetry tags 22 3.2.5 Tagging process 23 3.2.6 Tag data processing 25 3.2.7 Foraging habitat surveys 26 3.3 Results 27 3.3.1 Visual counts at haul-out sites 27 3.3.2 Public sightings distributions 29 3.3.3 Telemetry tag performance 32 3.3.4 Seal movement data 33 3.3.5 Spatial intensity of dives 37 3.3.6 Temporal foraging behaviour 45 3.3.7 Foraging ground surveys 48 3.4. Conclusions 49 3.4.1 Summary 49 3.4.2 Further work 50

Appendices Appendix I Seal recording forms used by seal counters at haul-out sites. Appendix II Queens University Belfast report of haul-out and foraging behaviour of Solent Seals. Appendix III List of foraging habitat towed video survey sites and results.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 v 1. Report aims and objectives

The Wildlife Trusts South East Marine Programme and Chichester Harbour Conservancy initiated the Solent Seal Tagging Project in December 2008. The project had the aim of gathering more information on the resident population of harbour seals in the area and improving their protection by incorporating this information in to the relevant conservation and management plans. This report is written as part of the Solent Seal Tagging Project and it is aimed at local conservation and coastal and marine management organisations and those further afield who are involved in seal research.

The first section of this report provides a basic introduction to the biology, ecology and conservation of UK seals. Much of the information contained in this section, notably details on populations and distributions, comes from the annual reports issued by the Special Committee on Seals (SCOS). The SCOS reports should be consulted for more information.

The second section details the Solent Seal Tagging Project, the aims, methods and results of the research carried out. The information presented in this report is a summary of the data gathered and analysis to date. Further data analysis will be undertaken in 2010 and reported on separately.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 1 2. Introduction to UK seals

2.1 Species types

There are two species of seal resident in the UK, grey seals, Halichoerus grypus, and harbour seals (often known as common seals), Phoca vitulina. At least four subspecies of harbour seal are recognised, the eastern Pacific, western Pacific, eastern Atlantic and western Atlantic. Only the eastern Atlantic subspecies P. vitulina vitulina occurs in Europe. Other seal species, including bearded, harp and ringed are occasionally sighted on UK shores but are not resident.

Of the two UK species the grey seal is the larger (Table 1). Identifying the two species can be done through size and differences in their head shapes. When looked at front on, grey seals have a double chin with the head appearing to be flattened on the sides. Harbor seals have a head that appears flattened top to bottom (Figure 1a & b). When seen in profile the shape of the two heads also differs, grey seals have a flatter ‘Roman’ nose whereas harbour seals have a more scooped, distinct forehead. The eyes of the grey seal are situated midway between the tip of the nose and the back of the head, the eyes on the harbour seal are further forward towards the front of the face (Figure 2a & b).

Table 1. Approximate sizes of grey and harbour seals occurring in the UK.

Grey seal Harbour seal Male Female Male Female Approx Length (m) 2.5 2.0 1.9 1.5 Approx Weight (kg) 350 200 120 100

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 2

Figure 1a Grey seal with a head flattened on Figure 1b Harbour seal with a head flattened the sides. Image by Bryony James. top to bottom. Image by mark Heighes.

Figure 2a Grey seal head profile with Figure 2b Harbour seal head profile with ‘Roman nose’. Image by Chas Spradbery. distinct forehead. Image by Chas Spradbery.

The colourations of the pelages (coats) also differ between the two species. Harbour seals often have uniformally spotted patterns with grey seals having more irregular blotches with distinct darker backs and paler bellies (Figure 3a & b). However pelage patterns and colouration can vary widely, there appearance can alter depending on if the coat is wet or dray and it is affected by moulting. The pelage can often take on a reddish hue throughout the year, becoming increasingly red towards the moult when the old fur is shed and the red hue is lost (Figure 4a). This is particularly the case for seals that haul out in muddy sites, such as in the Solent and the Thames Estuary, and is thought to be due to the presence of metals in the mud or possibly their prey. Towards the moult seals may become increasingly green due to the algal growth on their old coat (Figure 4b).

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 3

Figure 3a Grey seal with distinctive darker Figure 3b Harbour seal with more uniformally back and pale belly. Image by POEC. spotted pelage. Image by Mark Heighes.

Figure 4a Harbour seal with red tint to Figure 4b Harbour seal with green algal pelage. Image by Chris Bashall. growth on pelage. Image by Chas Spradbery.

2.2 Haul-out behaviour and habitat preferences

Seals come ashore to rest, mate, give birth and moult, a process known as hauling out. Harbour and grey seals typically have differing habitat preferences for hauling out. Grey seals tend to favour remote and exposed islands and coastlines, often on rocky shores. In contrast, harbour seals often occupy sheltered sandy and muddy bays, estuaries, harbours and offshore banks. However, the two species do overlap in some areas and harbour seals can be found in rocky areas and grey seals can be found in sandy and muddy areas. Seals are often faithful to their haul-out sites and will return to same one after foraging trips, however, grey seals particularly may travel to new haul out sites and forage from there.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 4 Harbour seals will usually haul out regularly, often linked with the tidal cycle, hauling out to rest at low tide when mud and sand banks become exposed, and moving off to feed when the banks become inundated with the rising tide. Grey seals will often haul out above the high water mark and so are less governed by tidal cycles. Both species haul out in groups with grey seals typically grouping closer together than harbour seals. When hauled out both species can often be seen with their head and tail ends curled up in to the air, possibly as these areas are relatively poorly insulated and so are lifted from the cold ground to conserve heat. Both species will spend more time ashore during the moulting period (December to April for grey seals, July to September for harbour seals).

If seals are on extended foraging trips they are able to sleep at sea, a process known as bottling where they hang vertically in the water with their head above the surface allowing them to breathe.

2.3 Feeding behaviour

Seals are the largest land based carnivorous predators in the UK. Both species are opportunistic, taking a variety of prey species depending on what is available locally during any particular season. Prey includes sand eels, cod, haddock, bass, mullet, herring, flounder and cephalopods. Seals are often sighted up river where they may be feeding on salmon, trout and grayling. As their prey suggests they are able to hunt in mid-water or on the sea bed and in murky conditions are able to use their long and sensitive whiskers to help locate prey.

In order to maintain blubber reserves and core temperature seals must eat fairly significant quantities, up to 5% or more of their body weight per day depending on the oiliness of the prey species.

Harbour seals will normally forage within 50-60km of their haul out sites on short trips, whereas grey seals may go on extended foraging trips several hundred kilometres from their haul outs and lasting several days.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 5 2.4 Breeding behaviour

Harbour and grey seals have distinct differences in breeding behaviour. Grey seals give birth in September to December, sometimes earlier in south west England. Seals usually choose remote islands and beaches to give birth where there is access to areas further inland so as t avoid storm waves. The pups, weighing up to 14kg, are born above high water and have a white coat that is not waterproof, so they remain high up on the shore for approximately 3 weeks until they moult this natal coat and develop an adult one, when they will take to the water.

Harbour seals pup in the summer months, typically June to August and as they often haul-out on intertidal mud and sand flats, where they will also give birth, their pups need to be able to swim almost immediately to avoid drowning. As a result the pups have a more waterproof coat, rather than the white coat of the grey seal pups, and take to the water on the first high tide. They will usually eight 8-12kg.

Seal pups will nurse for approximately 3 – 6 weeks and can more than double in weight due to the very high fat content of the mothers milk, up to 45%.

During the pupping and moulting season greater numbers of adult seals congregate on shore and spend increased amounts of time there, as a result it is an opportune time for mating. However, as the females are still recovering from their previous pregnancy they are able to delay the implantation of the fertilised egg so it remains free floating in the uterus for 6-12 weeks. This gives the females time to recover and increase their body mass through feeding and ensure that the pups will be born at the appropriate time of year, with gestation being approximately 9-11 months.

The life spans of the two species are similar with females living 25-30 years and males 20-25 years. Males reach sexual maturity at around 10 years and females at around 5 years.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 6 2.5 Distribution and population trends

Grey seals are found across the North Atlantic and the Baltic Sea. There are two centres of population in the North Atlantic; one in Canada, centred on Nova Scotia and the Gulf of St Lawrence, and the other around the coast of the UK, especially in Scottish coastal waters. The largest population is in Canada, however, approximately 45% of global populations do occur in the UK. Populations in Canada, UK and the Baltic are increasing.

Approximately 90% of British grey seals occur and breed in Scotland, the majority in the Hebrides and Orkney with other colonies in Shetland, on the north and east coasts of mainland Britain, including the Farne Islands, Blakeney Point, Donna Nook and Kent, and on the South and West coasts in Devon, Cornwall and Wales. There are also populations in Ireland.

Estimating total number of animals is problematic as the counts used as the basis for estimations are normally conducted when the animals are ashore and it can not be known what percentage of the population is ashore when the counting takes place. Pup production is therefore frequently used to estimate total populations through the application of population dynamics models, this work is carried out annually by the Sea Mammal Research Unit. In 2008 the UK total grey seal population was estimated as 206,000, the Special Committee on Seals report 2009 should be referred to for more detail.

Although the number of pups throughout Britain has grown steadily since the 1960s when records began, there is clear evidence that the growth is levelling off. The numbers born in the Hebrides have remained approximately constant since 1992 and growth is levelling off in Orkney and possibly in the northern North Sea, although some new colonies are being formed and populations in the central and southern North Sea are still growing. There are also clear indications of a slowing down in population growth in Canadian populations in recent years.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 7 Harbour seals are found around the coasts of the North Atlantic and North Pacific, from the subtropics to the Arctic. The harbour seals in Europe belong to a distinct subspecies which, in addition to the UK, is found mainly in Icelandic, Norwegian, Swedish, Danish, German and Dutch waters. Britain is home to approximately 33% of the population of the European sub-species. Harbour seals are widespread around the west coast of Scotland and throughout the Hebrides and Northern Isles. On the east coast, their distribution is more restricted with concentrations in Firth of Tay and the Moray Firth. In the Southern North Sea and eastern English Channel a large population exists in The Wash, with smaller populations in the Thames Estuary and off Ramsgate. In the central and Western Channel a small population exists in the Solent but they are otherwise rare. Scotland holds approximately 85% of the UK harbour seal population, with 11% in England and 4% in Northern Ireland.

Harbour seals are counted by the Sea Mammal Research Unit using aerial photography and thermal imaging during the moulting season, when most seals are likely to be ashore. Combining the most recent counts at all sites, approximately 27,400 harbour seals were counted in the British Isles, of which 20,000 were in Scotland, 3,200 were in England, 1,250 were in Northern Ireland and 2,900 in the Republic of Ireland. Not all individuals in the population are counted during surveys because at any one time a proportion will be at sea. It has been estimated that at any one time 60-70% of the population are hauled out during the moult surveys, leading to an estimate for the total British population of 40,000 – 46,000 animals.

The population along the east coast of England, notably in The Wash, was reduced by over 50% following the 1988 phocine distemper virus (PDV) epidemic. A second epidemic in 2002 resulted in a decline of over 20% in The Wash, but had limited impact elsewhere in Britain. Counts in the Wash and eastern England suggest populations have failed to recover since the epidemic and are still approximately 60- 70% of pre-epidemic levels, in contrast to the adjacent European colonies which have experienced rapid growth since 2002.

Major declines have now been documented in other harbour seal populations, notably around Scotland, with declines of up to 50% since 2000. It is unknown what is

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 8 responsible for these declines. A lack of dead seal carcasses washed up on the shore and tests on live and dead seals suggest there is no current outbreak of PDV or other diseases to explain the current declines. Other potential factors suggested are competition for prey with grey seals where the two species ranges overlap, increased predation from orca’s off areas such as Shetland and Orkney and increasing numbers of seals killed by fishermen.

2.6 Conservation measures

Traditionally seals have been hunted in the UK for meat, oil and fur. By the early 1900s commercial hunting had reduced seal populations to critically low numbers. Grey seals were hunted almost to extinction in the UK and became the first mammal to be protected by law - the Grey Seals Protection Act of 1914. However, seals have often been cited as competition for fisheries and from 1962 to 1983 there was an annual cull of grey seals. It has been recently estimated by some campaign groups that up to 5000 seals may be killed each year by fishermen and fish farmers, however this figure has been contested. It is recognised that there needs to be more accurate reporting on the numbers of seals killed to determine impacts on populations.

There are several conservation designations applied to grey and harbour seals in the UK.

Conservation of Seals Act 1970 The Conservation of Seals Act 1970 was put in place to allow seals some protection during their breeding and moulting seasons when they are most vulnerable. It prevents the killing of grey seals from the 1st September to the 31st December and harbour seals from 1st June to 31st August. The Act also limits the methods available for killing seals, with poisoning and inappropriate firearms being unlawful. However, it is acceptable under the Act to kill seals inside and outside of the close seasons with a licensed firearm if the seals are thought to be interfering with fisheries interests, such as nets, or predating fish within the nets. Seals may also be shot if found predating fish, such as salmon, in fin fish farms. Since the Act came in to force only one person has been successfully prosecuted under it.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 9 Conservation of Seals (Scotland) Order 2004 and 2007 These Orders were introduced in response to concerns about recent declines in harbour seal numbers. The 2004 Order extended the ‘close season’ for grey seals and harbour seals within the Moray Firth all year round. The 2007 Order does the same for harbour seals in Shetland, Orkney and an area of the east coast between Stonehaven and Dunbar. However, the exceptions that exist in the Conservation of Seals Act 1970 remain in these Orders, so it is lawful to continue to shoot seals in these areas if they are interfering with fisheries.

Conservation (Natural Habitats etc) Regulations 1994 (as amended) The EC Habitats Directive (Council Directive 92/43/EEC) aims to contribute to the conservation of biodiversity by taking measures designed to maintain or restore certain natural habitats and wild species to 'favourable conservation status'. This includes specific duties for the designation of Special Areas of Conservation (SACs). In the UK the Directive has been transposed into national laws by means of the Conservation (Natural Habitats, & c.) Regulations 1994 (as amended), and the Conservation (Natural Habitats, & c.) Regulations (Northern Ireland) 1995 (as amended). These are known as 'the Habitats Regulations'.

Grey and harbour seals are species listed under Annex II of the Directive and can therefore have Special Areas of Conservation designated around them for their conservation.

There are 9 SAC’s designated for harbour seals, 8 in Scotland and 1 in England, plus a further two sites in Northern Ireland where harbour seals are a qualifying feature, but not a primary reason for site selection. There are 7 SAC’s designated for grey seals, 6 in Scotland and 1 in Wales. There are a further 5 SAC’s where grey seals are a qualifying feature, but not a primary reason for site selection.

Special Areas of Conservation are usually placed around the haul out sites for the animals, key foraging areas may not be protected if the seals travel outside of the site boundaries to feed. It can still be lawful to shoot seals adjacent too and within SAC’s designated for the presence of the seals.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 10 Marine and Coastal Access Act Under the Marine and Coastal Access Act 2009 the English parliament is committed to designating new protected sites around the coast of England known as Marine Conservation Zones.

The Convention on the Conservation of European Wildlife and Natural Habitats (The Bern Convention) The Bern Convention was adopted in Bern, Switzerland in 1979, with the UK ratifying it in 1982. The principal aims of the Convention are to ensure conservation and protection of wild plant and animal species and their natural habitats. To this end the Convention imposes legal obligations on contracting parties, protecting over 500 wild plant species and more than 1000 wild animal species. The Convention was implemented in UK law by the Wildlife and Countryside Act (1981 and as amended), it also had an influence on the Conservation (Natural Habitats &c.) Regulations 1994.

Both species of seal are listed in Annex III and Contracting Parties are required to prohibit the use of all indiscriminate means of capture and killing and avoid causing local disappearance of, or serious disturbance to, populations. In England, guidance documents list species for which Marine Conservation Zones can be designated. This list does not currently include grey seals, and so sites may not be designated for their presence. It does include harbour seals but implies they will only be designated under exceptional circumstances.

Marine (Scotland) Bill In Scotland, the Scottish Parliament passed the Marine (Scotland) Bill in February 2010, which also enabled the designation of new Marine Protected Areas. The Marine Bill (Scotland) introduces new legislation specifically for the conservation of seals and replaces the Conservation of Seals Act 1970 in Scotland. It will now be an offence to kill seals at any time of the year without first being granted a licence and this includes the killing of seals for interfering with fisheries. It will also be a requirement to report any seal shot. The Bill will introduce a new offence of harassment of seals at haul-out sites.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 11 Biodiversity Action Plans As well as statutory protection, seals are also included in non-statutory conservation plans and both species are listed as a UK Priority Biodiversity Action Plan (BAP) species. Whilst this does not offer them any protection in law, it can be of benefit in raising awareness of the species, encouraging population counts and monitoring, implementing voluntary codes of conduct and flagging them up in planning and development processes. There is currently no national Species Action Plan but several organisations have developed local plans for these two species.

2.7 Seal population counts and monitoring methods

The Natural Environment Research Council (NERC) has a duty to provide scientific advice on seal populations to Government under the Conservation of Seals Act 1970. NERC has appointed the Special Committee on Seals (SCOS) to formulate this advice. The Sea Mammal Research Unit (SMRU) provides advice to SCOS and conducts a regular national programme of seal counts.

Since 1988 SMRU has been carrying out surveys of harbour seals during the moult in August. It was considered to be impractical to survey the whole coastline every year and SMRU aimed to survey the whole coastline across 5 consecutive years. However, in response to the observed declines around the UK an attempt was made to survey the entire Scottish and the English east coast populations during 2007. SMRU uses a combination of aerial photography and thermal imaging to carry this out.

SMRU has also been carrying out annual grey seal counts since 1960, often employing aerial surveys of the major breeding colonies to determine the number of pups born, which is modelled to estimate total population size.

Some colonies are monitored annually, often by the land owners where seals haul out. National Trust staff count pups born at the Farne Islands and at Blakeney Point in Norfolk. Staff from the Lincolnshire Wildlife Trust count pups born at Donna Nook and staff from Countryside Council for Wales, Natural England and Scottish Natural Heritage have counted pups born at sites across there respective areas. Active

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 12 volunteer groups also organise counts in areas including Kent and across the South West.

There are various options for counting and monitoring seal population size and movements and each has advantages and disadvantages, meaning a combination of approaches are often the best. There are also established techniques for monitoring population dynamics, such as recruitment and mortality, population structure, such as sex and age, and genetic diversity. Table 2 lists some of the more frequently used methods for monitoring population size and behaviour.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 13 Table 2. Seal monitoring techniques.

Method Advantages Disadvantages Visual census from shore or boat –Carried out at • Gives accurate counts in localised areas. • May give limited geographical coverage per tide so low tide when animals are hauled out, often during • Distinguish species. restricts numbers of haul-outs visited and therefore the moulting season as animals spend increased • Can allow high resolution photography for confidence in total estimates. amounts of time ashore. Ideally all haul outs should subsequent PhotoID. • Not all animals will be hauled out at the time of the be visited in single low tide to ensure animals have • Relatively cheap. counts and so may have under estimates of not moved haul outs and been double counted. • Observers do not need specialist skills or population size. equipment. • Can be carried out regularly. Aerial photography – using fixed wing planes of • Can give accurate counts. • In rocky or seaweed covered habitats seals can be helicopters to fly over haul outs taking pictures to • Can cover large areas and multiple haul-outs in difficult to spot. subsequently identify number of seals single low tide. • Expensive and requires specialist equipment. • Can identify to species level. • Not all animals will be hauled out at the time of the counts and so may have under estimates of population size. Thermal imaging cameras – as above but using • Can give accurate counts. • Can not distinguish between species. thermal imaging cameras. Often, photography and • Can highlight even well camouflaged seals in • Not all animals will be hauled out at the time of the thermal imaging are used in conjunction. rocky and seaweed covered habitats. counts and so may have under estimates of • Can cover large areas and multiple haul-outs in population size. single low tide. Mark and recapture – involves catching the • Tags are cheap. • Requires catching the animal (unless using spray animals, attaching some kind of identifiable tag to • Some tags, such as flipper tags, may last many paint on seal pups) needs specialist skills and can be them, releasing them and either recapturing at a years. dangerous, also more distressing for the animals, later date to ID the seal from the tag or if the tag is may need anaesthetising. identifiable from a distance carrying out visual • Some tags only really visible if seals are recaptured. surveys. Tags have included flipper tags (often not • Tags may fall off or interfere with normal seal identifiable from a distance), plastic conical hats behaviour. and spray paint for identifying grey seal pups. Photo Identification – A form of mark and • Can identify individuals. • Can be difficult to get close enough to take quality recapture but using natural marks on the seal pelage, • Can allow total population size to be estimated images without disturbing the seals. which are unique to each individual. High quality over time, especially if combined with visual • Photographing and subsequent image analysis is time images of the seals can identify individuals and surveys, although only really feasible in smaller consuming, especially if large populations and many

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 14 allow population size and movements to be more localised populations. images. distinguished. Seals best photographed when clean • Can identify if individuals leave or join a group. • Can be difficult to photograph in optimum and wet. • Can exchange records with other monitoring conditions, animals may be dry, covered in mud, groups to determine seal movement between moulting or have discoloured pelages or covered in neighbouring populations. algae. • Relatively cheap with little technical expertise or equipment needed. • Some specialist software is available for initial comparison of images. Telemetry based tags – uses remote devices, • Can gather and transmit data on seal behaviour • Requires catching and anaesthetising the animal so attached to seals that gather data and transmit it when the animal is away from the haul out and out needs specialist skills and can be dangerous, also back to a receiving station. Seal telemetry tags may of sight. more distressing for the animals. gather location data, dive data, such as depth and • Can gather very high resolution data on location at • Often not practical to tag whole populations so only duration, and haul out data. Various forms of all times of day and night over a period of several gives data on a sub-set. telemetry based tags have been used including VHF months. • Some methods of telemetry better than others, VHF radio, satellite and tags using GPS and mobile • Can gather a variety of data from location to dive requires tracking the seal at its haul out or at sea, phone technology. and haul out behaviour. satellite (such as ARGOS) can give poor spatial • Initial cost can be expensive but very cost resolution. effective.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 15 3. Solent Seal Tagging Project

3.1 Introduction

3.1.1 Project background The English Channel hosts several populations of seals with grey seals being found in Devon and Cornwall and grey and common seals being found off the coast of Kent, having populations between South Foreland and Ramsgate on the east coast and in the Thames Estuary off the north coast. In the central and eastern English Channel, between Devon and Kent, seals are a rarity and the only confirmed resident population is of harbour seals in the Solent, although seals are sighted occasionally along the entire stretch of coastline.

Despite the regional importance of the Solent population, little information about it was available. Precise numbers, age classes, sex ratio’s, foraging and breeding areas were unknown. As a result, they were not adequately accounted for in local conservation and management plans and their presence was not considered in the various coastal development proposals that may affect them.

In partnership with Chichester Harbour Conservancy, the Wildlife Trusts’ South East Marine Programme initiated the Solent Seal Tagging Project in December 2008 with funding through to March 2010. Funding was provided by: • Sita Trust • Natural England Countdown 2010 Biodiversity Action Fund • Chichester Harbour Conservancy • Friends of Chichester Harbour • Hampshire and Isle of Wight Wildlife Trust • Environment Agency • Solent Forum

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 16 3.1.2 Project aims The overarching aim of the project was to gather robust information on the Solent seal population in order to inform current and future conservation and management plans and ensure they were considered in the designation of any Marine Conservation Zones.

Specifically the project aimed to:

1. Carry out boat based and shore based surveys to provide accurate population counts and identify the most important haul-out sites. 2. Seek to identify each individual seal on the basis of their pelage by developing a photo-identification database to aid monitoring over the long term. 3. Deploy telemetry based tags on a sub-set of the population, providing information on movements and dives around the area that would indicate haulout, foraging and breeding behaviour and if there is movement between this population and those to the east in Kent or south in France. 4. Survey the primary foraging grounds identified through the use of the tags to determine preferred feeding habitat and prey type. 5. Raise public awareness through a code of conduct, a public reporting scheme, a formal education pack and through local media and offering talks to local interest groups.

The information gathered would give a detailed understanding of the seal population, highlighting the areas that they are most reliant on. This information will be incorporated in to the various management plans and Biodiversity Action Plans associated with the area to help ensure that the most vital sites benefit from protection.

3.1.3 Site characterisation The Solent is the area encompassing the northern Isle of Wight and the mainland coast of Hampshire and the eastern most part of West Sussex. The Solent is one of the few major sheltered channel systems in Europe and the whole area is unique in Europe in oceanographic terms. It was formed during the melts of the last Ice Age,

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 17 which drowned the Solent River system that once flowed east between what is now the Isle of Wight and mainland Hampshire and West Sussex. The flooding of this river valley resulted in a relatively shallow area of sea about 40 km long from east to west, with a width of about 4 km in the western Solent and about 10 km at the eastern end. Within the Solent, tidal streams in the main channel range from 2.5 kn in the east to 4 kn in the west. The waters are characterised by high levels of turbidity.

Numerous estuaries and natural harbours were formed during the flooding of the river valley, the largest of which are Portsmouth, Langstone and Chichester. These harbours effectively operate as a single system, comprising of connected intertidal basins drained at low water by complex networks of channels and creeks. It is these shallow harbours with their extensive intertidal mud and sand banks where the seals were most frequently observed. On the Isle of Wight, the most significant sheltered areas are Newtown Harbour and the estuaries of the Yar, Medina, Wootton Creek and Bembridge Harbour. The predominantly eastward longshore drift has lead to the formation of spits and bars at the entrance to many of the estuaries and harbours. The deposition of sediments in these sheltered areas has given rise to extensive mud and sand flats.

The complex shape of the Solent, its varying geology, many rivers, unusual tidal cycle and its location on the transition between the warm ‘Lusitanian’ waters of the western Channel and the cold ‘Boreal’ waters of the Eastern Channel have meant a great diversity of habitats, flora and fauna. This has given rise to many features of international, national and regional conservation importance and a wide variety of potential prey species for seals, with large populations of flatfish, bass, mullet and mackerel and, further offshore, sand eels. The chalk rivers of the Test and Itchen, which flow in to Southampton Water and the Solent, are famous for their populations of salmon and trout. Almost the entire coast on both the northern Wight and the Hampshire side is designated as either a Special Area of Conservation, Special Protection Area or Site of Special Scientific Interest.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 18 The Solent has attracted a great deal of economic development with shipping, sailing, fisheries and marine aggregate extraction all taking place. The land area surrounding the Solent is highly urbanised, and the river basins predominantly agricultural. All these activities have influenced the physical, chemical and biological state of the Solent. It is considered to have high levels of Tri-butyl Tin and some other metals and Polycyclic Aromatic Hydrocarbons. Portsmouth, Langstone and Chichester Harbours have shown symptoms of eutrophication with excessive macroalgal growth on mudflats. These sites have been designated as Sensitive Areas under the Urban Waste Water Treatment Directive. Agricultural run – off and inputs from the wider Channel further nutrient loading.

3.1.4 History of the Solent seal population As stated, very little was known about the Solent seal population and few dedicated studies had been conducted. However, various organisations, notably Chichester Harbour Conservancy, have been recording observations over a number of years at one of the main haul out sites in Chichester Harbour. As a result some information on approximate population size and growth over the last 15 years was known. Also, other organisations, such as the Wildlife Trusts, have been gathering public sightings of seals for over a decade.

In 1993 a harbour seal pup was found at East Head, close to the entrance of Chichester Harbour. The seal was moved to a rehabilitation centre and subsequently released in The Wash, as at the time it was not thought that there was a resident population in the harbour. However, anecdotal evidence from anglers and sailors suggest seals have been in Chichester and surrounding harbours for several decades prior to this and were seen hauled-out on boats and mud banks.

In 1994, regular reports of a female harbour seal with a damaged hind flipper were received from various locations around the Solent and it was believed to be pregnant, although what happened to any pup is unknown. Later that year, this female and two male harbour seals were seen hauled out together in Chichester Harbour and since then the population appears to have grown at a slow but steady rate (Figure 5), aided by the introduction of three rehabilitated seals. At the start of the project in December

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 19 2008 the total population of harbour seals in the Solent was estimated at between 16 and 20 individuals.

18 16 14 12 10 8 6

No. harbour seals harbour No. 4 2 0 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Year

Figure 5 Maximum number of seals counted at any one time in Chichester Harbour.

As well as Chichester Harbour, harbour seals were often seen hauled out on the mud flats in the adjoining Langstone Harbour and public sightings have placed them across the Solent and wider South East.

As well as the resident population of harbour seals, which typically enjoy the sheltered conditions and intertidal mudbanks that the Solent offers, grey seals are also reported in the area. Grey seals are in low numbers, possibly only one or two at a time, it is not known if these are transitory seals or if they have taken up residence, but one or two individuals have been noted in the area for two consecutive years. They can often be seen hauled-out in the same sites as the harbour seals.

3.2 Methodology

3.2.1 Visual surveys Dedicated visual surveys of the seals at their two main haul-out locations, one in Langstone Harbour and one in Chichester Harbour, have been conducted from December 2008 to February 2009 using a combination of boat and shorebased

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 20 surveys. They have been carried out by several organisations, Portsmouth Outdoor Education Centre and Langstone Harbour Board have submitted records for Langstone Harbour and Chichester Harbour Conservancy and the National Trust have submitted records for Chichester Harbour. On several occasions, the two haul-outs have been surveyed during the same Low Tide to give a more accurate estimate of total population size. Survey forms were designed to ensure the information gathered was consistent (see Appendix 1) and these were also given to other organisations in the area in case of ad-hoc sightings.

3.2.2 Public sightings As well as dedicated counts at haul-outs, a public sightings scheme was initiated to gather records across the wider Solent and South East area. A leaflet was produced that outlined identification techniques for distinguishing between the two species and a code of conduct to minimise seal disturbance. The leaflet had a tear-off sightings form included. A separate online recording form was hosted on the Hampshire and Isle of Wight Wildlife Trust website (www.hwt.org.uk). The scheme was promoted using local media and coastal networks and through a programme of talks given to coastal user groups including scuba divers and recreational sailors.

3.2.3 Photo Identification During the seal capture and tagging process and the boat based visual counts, photographs were taken of as many of the seals as possible, either hauled out or in the water. Members of the public were also encouraged to send in photographs.

Capturing high resolution detailed close up images of the seals was sometimes problematic. To get close enough to the seals boats had to be used and taking images from a moving platform with a long lens, often of a moving animal sometimes led to blurring of the image, reducing its suitability for subsequent analysis. The softness of the mud meant that landing the boat and getting on to shore for a more stable platform was also difficult. Also, when hauled-out, the seals would often be coated in mud which disguised the pelage markings.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 21 Initially it was decided to use image analysis software produced by Lex Hiby of Conservation Research, Cambridge, designed specifically for harbour seals. However, discussions with other organisations experienced in seal PhotoID have suggested that with such a small population it may be quicker and more accurate to analyse the images by eye.

The PhotoID work will be an ongoing programme of work and will not be reported on here, more images and detailed analysis is required and the results will be published in a second report later in 2010.

3.2.4 Telemetry tags The tags used in this project were designed and built by the Sea Mammal Research Unit (SMRU), St Andrews (Figure 6). Known as Fastloc GPS GSM tags, they collect location data using the Fastloc GPS system (Wildtrack Telemetry Systems, UK), which collects the data required for a GPS location within a fraction of second. They were programmed to attempt a location fix every 30 mins using a minimum of five satellites for a high degree of accuracy.

Figure 6. Fastloc GPS GSM tag (recovered after deployment).

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 22 As well as location data, the tags record other information. Haul-out behaviour is recorded using a wet/dry sensor. A haul-out starts when the tag is continuously dry for 10 mins and ends when it is continuously wet for 40s. Detailed dive data is also gathered that allows dive depth and duration to be ascertained, which indicates foraging behaviour.

The data gathered is relayed to the groundstation at SMRU using the GSM mobile phone system, allowing far greater data transfer rates, with greater energy efficiency than previous systems. The tags operated on the Vodafone network, the data is stored onboard and programmed to be phoned through every 6 hours.

Once received at SMRU, the data is processed and uploaded to their website for download (password protected). Data is available in both Google Earth files for quick visualisation and as an Access Database for in depth analysis.

The tags have a battery life of approximately 6 months, depending on how frequently data is gathered, and fall off the seal during the annual moult in July / August (although they can become dislodged before this), so in order to maximise the amount of information gathered, January to March is the best time to deploy the tags. However, one tag deployed during this project was continuing to transmit location data nearly 1 year after deployment, it came off the seal and was subsequently washed on to an intertidal mud bank and recovered.

3.2.5 Tagging process Successfully and safely capturing and tagging seals requires a licence, a high level of experience and specialised equipment. SMRU led the tagging operations with support from the Wildlife Trust and Chichester Harbour Conservancy.

Tagging took place from the 18 – 21 March 2009 at the two haul-out sites in Chichester and Langstone Harbours. It was timed to coincide with Low Water Neap tides when the seals would be hauled-out. The most successful method employed consisted of using two boats, with the first boat encircling the haul-out and dropping one end of a net to be picked up by a second boat. The two net ends were then taken

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March 2010 23 to shore and the net was pulled in, corralling the seals onshore. Once captured, they were weighed and anaesthetised.

When under the anaesthetic, the seals were photographed, measured and their general condition checked. Blood and skin samples were taken for subsequent analysis for disease and genetic tests by SMRU. The Fastloc GPS GSM tags were fixed to the back of the neck using an epoxy resin. Each captured seal was also fitted with a hind flipper tag. Once the animals had come round from the anaesthetic they were allowed to make their own way in to the water and were monitored for several minutes to ensure they were functioning normally.

In total, six harbour seals were captured, four in Chichester Harbour and two in Langstone Harbour. Five seals were tagged with the Fastloc GPS GSM tags and all six were flipper tagged. Of the captured seals, five were adult males and one a juvenile female Table 3 summarises the seals tagged. It is not known why no adult females were caught, the ratio caught may indicate a low number of adult females in the population or it may have been that the adult females were more wary and moved in to the water before the nets were deployed.

One of the male seals caught had previously been flipper tagged, the tag had gone but the puncture mark in the hind flipper was apparent. It is possible that this animal was the male that was found in 1995 as a 1 week old pup in Christchurch Harbour, rehabilitated at Hunstanton Sealife Centre in Norfolk and released in to Chichester Harbour in 1996, which was flipper tagged prior to its release.

Table 3 Tagged seal data. Axial Deployment Deployment Weight Length girth Seal Tag ID location date Sex Age (kg) (cm) (cm) pv26-01-09 Langstone 19/03/2009 M Adult 98 144 116 pv26-02-09 Chichester 18/ 03/2009 M Adult 107.2 155 118 pv26-03-09 Langstone 19/03/2009 M Adult N/A 144 119 pv26-04-09 Chichester 19/03/2009 F Juvenile 54.6 122 98 pv26-05-09 Chichester 21/03/2009 M Adult N/A 150 114 N/A Chichester 21/03/2009 M Adult N/A 147 112.5

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 24 3.2.6 Tag data processing Data from the fastloc tags was downloaded from the SMRU website in Google Earth and Microsoft Access formats for analysis. The data was shared with Queens University Belfast (QUB) and Hampshire and Isle of Wight Wildlife Trust (HIWWT) for processing and analysis.

Data was analysed for: • Haul-out behaviour o The location of key haul-out sites.* o The haul-out duration for each seal (total tracking period).* o Temporal shifts in haul-out behaviour for each seal throughout total tracking period.* • Diving and foraging behaviour o Areas of overall habitat usage. o Spatial intensity of foraging activity. o Home ranges during foraging trips.* o Distance travelled during foraging trips.* o Duration of foraging trips.* o Rate of travel during foraging trips.* o Dive depth and water column usage.* o Temporal shifts in foraging behaviour.

* Indicates analysis carried out by QUB, for a full report on the methods used and results of this analysis see Appendix 2

To illustrate overall habitat usage HIWWT imported the GPS data files in to MapInfo with Seazone Hydrospatial background. There were some inaccurate points, either on land or far out to sea, these were deleted. These GPS data points were then compared to the dive location data points and there did not appear to be significant discrepancies at a coarse scale so were sufficient to highlight general movement and foraging trends.

Foraging intensity was also examined to determine if any specific locations

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March 2010 25 were visited more frequently by the seals, therefore highlighting areas of particular importance to the animals. This was done using the dive data locations not the GPS data points. Each dive point has a start and an end point, the mid point of this track was calculated and plotted in MapInfo. All dives less than or equal to 1.5m depth were deleted as they may have been travelling at this depth rather than foraging. All dives which were plotted to occur on land were deleted as erroneous points. The total sea area was then overlayed with a 100m x 100m grid and the number of dives in each of these grid squares was counted. This effectively gave a map showing where seal diving was most frequent which in turn indicates areas most important for foraging.

3.2.7 Foraging habitat surveys Salacia Marine (www.salacia-marine.co.uk) were contracted to survey the seal foraging grounds in order to determine any preference for foraging habitats. The foraging sites were identified by a GIS analysis of the dive data recorded by the tags. Dive depth data was sorted into depth classes; 2-5, 5-10, and >10 m, anything less than 2m was discounted as it may the seal may have been travelling rather than actively hunting. These depth classes were colour coded in the GIS and plotted. Aggregations of dives were assumed to indicate foraging areas and those areas targeted for video survey.

The video surveys took place between Monday 20th – Friday 25th July 2009. During this period the weather was consistently unsettled with winds averaging F4-5. Foraging areas were targeted with respect to prevailing conditions and harbours worked when high winds precluded working in the open sea. The surveys adopted a stratified random survey approach in order to efficiently target seal foraging areas identified in the GIS analysis. Video survey work was carried out using Salacia- Marine’s underwater video equipment: • 50 m underwater colour video camera and umbilical • Video sledge and warp • Video fish • 2 x underwater lights/dive torches • Topside control box with GPS overlay, DVR and power pack Survey work was carried out in partnership with Sussex Sea Fisheries

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 26 Committee and Chichester Harbour Conservancy. These organisations supplied two vessels and crews: • Sussex SFC Fishery Protection Vessel Sea Harrier - 8.7 m RIB • Chichester Harbour Conservancy Vessel – Cheetah Cat

Each of the areas was visited and a series of video tows undertaken. The number of tows was determined by weather, tidal and time constraints. During the survey a field log was maintained and key observations noted.

Scuba diving surveys were also attempted at two sites, one off Selsey Bill and one of Ryde, however difficult diving conditions meant that little information could be added to the video data.

3.3 Results

3.3.1 Visual counts at haul-out sites From the visual counts at the two haul-out sites, average numbers of harbour seals have been calculated per month (Figure 7a & b.). More counts were taken in Langstone Harbour, an average of 14 counts per month, and during more months, meaning the data for Langstone is likely to give a good understanding of haul-out behaviour in this harbour. Fewer counts were conducted in Chichester, an average of 2 per month, and only for a limited number of months, meaning absolute figures are less likely to be representative. This makes interpretation more problematic as the results for Chichester Harbour are less robust. However, it is reasonable to suggest that the haul-out in Chichester Harbour is consistently used by the largest number of individuals, with a maximum of 16 seals at any one time and an average of 10.7, compared to a maximum of 7 at Langstone with an average of 3.3.

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March 2010 27 18 16 14 12 10 8 6 Number of Seals 4 2 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month

Figure 7a. Averaged 2009 monthly counts of harbour seals in Chichester Harbour (bars) with maximum count in each month (line).

8 7 6 5 4 3

Number of Seals 2 1 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month

Figure 7b. Averaged 2009 monthly counts of harbour seals in Langstone Harbour (bars) with maximum count in each month (line).

In order to better estimate total population size, on several occasions counts were taken at each haul-out on the same day on the same Low Tide (Figure 8). The greatest number of seals hauled-out at any one time across both haul-outs is 18, giving this as a minimum estimate of the total number of harbour seals in the Solent population. The Sea Mammal Research Unit has estimated that approximately 60-70% of seals may be hauled out at any one time during the moulting period. If this is

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March 2010 28 applied to the Solent counts it would give a total population estimate of 23 – 25 seals. However, the estimate of 60-70% of seals being hauled-out is for the moulting period, when it is most likely that seals will be ashore. The maximum Solent count of 18 was during March, outside of the moulting season. As a result, a greater number of seals may have been at sea and so the figure of 23 – 25 may be an underestimate.

20 18 16 14 12 10 8

No. Seals 6 4 2 0

9 9 9 .09 0 0 .09 .0 4. 5. .02 0 0 .06 .07 2. 17 29.03.09 30.03.09 1 12. 14.05.09 11 08 28.07.09 Date

No. at Chichester No. at Langstone Total No. Seals

Figure 8. Harbour seal counts at both haul out sites on the same tide with total number of seals counted across the area.

3.3.2 Public sightings distributions Over 700 seal sightings from members of the public and local harbour wardens have been gathered, dating from 1985 to 2010. Many sightings have come from sailors, kayakers and rowers, who report that the seals will often approach their boats and interact for several minutes, swimming under the boats, mouthing them and even trying to haul-out on them. Swimmers have also reported being followed at close range by the seals. Sightings have been submitted from outside of the Solent and surrounding area, notably from East Sussex, but these have not been included in this report. As with all public sightings schemes, the records are ad-hoc and effort related so they do not give definitive evidence of distribution. There is bias towards haul-out sites and semi-enclosed water bodies where they are most visible and where there are relatively more people. There is also the potential for species mis-identification. Despite this, the results do demonstrate some interesting trends.

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March 2010 29 Figure 9 shows all sightings grouped by species. Seals have been seen throughout the Solent, further east in Pagham Harbour and on the south side of the Isle of Wight. As expected, they are most commonly reported in the harbours and Southampton Water, probably an artefact of there being a large number of people and the seals being closer to the shore. The seals do move up river and have been seen up the River Hamble, Test and Itchen. They travel some distance inland, a seal was spotted in February 2010 at the Woodmill Activity Centre on the River Itchen, 8km from the confluence of the river and Southampton Water and 20km from the mouth of Southampton Water. The species is unconfirmed, several sightings were reported in the same area over a number of days, some saying grey and others saying harbour, it is possible both species were present.

Figure 9 Locations of public sightings of seals from 1997 to 2009. NB Many sightings

have very similar coordinates and so do not show clearly at this scale. © British Crown and

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 30 The sightings data suggests that seals are less frequently seen in the Western Solent than the Eastern Solent, possibly due to a lack of survey effort in this area but it is likely this is indicative of true behaviour. Harbour seals occur most frequently in the Eastern Solent, from Southampton Water to Selsey Bill, and are rarely seen in the Western Solent. In the Western Solent grey seals are the species most frequently recorded. Similarly, grey seals are the species most often reported from the south of the Isle of Wight. Grey seals are known to range further on foraging trips than harbour seals which may explain this trend.

Seal sightings were plotted on the basis of numbers of individuals to determine if there were any locations where groups of seals (more than one) were seen as opposed to lone seals, which may indicate unknown popular haul-out areas or occasions when seals may forage together (Figure 10). The main areas where groups of seals were reported are the two known haul-out sites in Langstone and Chichester Harbours. Groups were also seen in Pagham Harbour and in two locations in Southampton Water, but these were occasions when just a pair of seals was seen and they were in the water.

Figure10. Public sightings of lone and groups (more than 2) of seals from 1997 to

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 31 In the last 7 years only three seals have been reported dead, although more may have been found. In June 2006 a dead seal was reported in Chichester Harbour with no apparent injuries. A seal of unknown species was reported dead at Brook Chine, Isle of Wight, in November 2009. Brook Chine faces the prevailing South Westerly winds and various species of seal and cetacean have been washed up there over the years. It was not possible to access information on seal species or condition so it is unknown if had recently died or perhaps been in the water for some time and been blown up the Channel from outside of the area. In August 2009 a dead seal was reported on the beach near Netley, Southampton Water. This was confirmed as a female harbour seal, it had been on the beach for at least 24 hours when it was visited and photographed. The fur had been removed, possibly as a result of abrasion on the pebble shore, and so photoID was not of any use in determining if it was a known individual of the Solent population. However, considering its location it is likely it did belong to the group. There were no obvious external physical injuries to indicate cause of death and it was not removed for autopsy.

3.3.3 Telemetry tag performance It is important to remember that the tag results only illustrate the behaviour of a limited number of seals (approximately 20 - 25% of the estimated population), the seals often illustrate quite individual behaviour and so it is possible that the untagged seals may behave in a different way and visit different areas. It is also important to note that the tags only illustrate behaviour during the period March to July, it is possible that the seals may behave in a different way during the other months.

The haul-out and foraging data analysed by Queens University Belfast is presented in Appendix 2, only data analysed by Hampshire and Isle of Wight Wildlife Trust is presented in the body of this report.

A total of 520 days of tag data was collected, and average of 104 days per seal (approximately 3.5 months) (Table 4). One tag pv26-02-09 malfunctioned after 67 days, the seal was seen still with it fixed but the tag was no longer transmitting. All other tags appeared to continue to transmit until the fell off the seals. Two tags fell off in intertidal areas, one was collected a couple of days after, the other tag continued to

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March 2010 32 transmit until February 2010, nearly a year after deployment, when it was collected.

Table 4. Tag duration data.

Deployment Tag transmission Tag ID location Deployment date Loss date duration (days) pv26-01-09 Langstone 19/03/2009 23/07/2009 126 pv26-02-09 Chichester 18/03/2009 24/05/2009 67 pv26-03-09 Langstone 19/03/2009 20/07/2009 123 pv26-04-09 Chichester 19/03/2009 18/06/2009 91 pv26-05-09 Chichester 21/03/2009 12/07/2009 113 Total number transmission days 520 Ave number of days per seal per seal 104

3.3.4 Seal movement data GPS data from the tags is shown in Figure 11a to f. All five seals stayed almost entirely in the Eastern Solent, from Southampton Water in the west to Selsey Bill in the east. Only on two occasions did the seals travel further east than Selsey Bill. The major harbour complexes were repeatedly visited, Langstone and Chichester Harbours, where their two main haul out sites are located, were most often used by the seals. The data shows that the seals will utilise both of the two main haul-out sites in Chichester and Langstone Harbours. Portsmouth Harbour and Bembridge Harbour on the Isle of Wight were also visited.

When the seal movements are looked at individually it is apparent that the seals often display quite different foraging patterns. pv26-01-09 stays almost entirely within Portsmouth, Langstone and Chichester Harbours and will often travel between them using the connecting channels rather than going through the harbour entrances. Three of the five seals made frequent trips to the Isle of Wight, the remaining two did not visit. Only one seal, pv26-03-09 spent any time in Southampton Water, it was also one of only two seals to travel east of Selsey Bill, which it did just once. The only female seal tagged, pv26-04-09, had very localised foraging behaviour, making very regular trips between the haul-out in Chichester Harbour and Selsey Bill, never going elsewhere. In contrast, pv26-05-09 was the most wide ranging, visiting the three Hampshire harbours, the Isle of Wight and travelling the furthest of any seal to Shoreham in West Sussex, a two day trip with a distance of approximately 60km from its haul-out site and a trip distance of approximately 160km. It was on this

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March 2010 33 trip the greatest dive depth was recorded at 59.4m. Further data on foraging trip distance and dive behaviour is presented in the QUB report.

Figure 11a. Map showing all GPS positions for all five seals for tracking duration. ©

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March 2010 34

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March 2010 35

Figure 11f. All GPS points for seal pv26-05-09.

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March 2010 36 3.3.5 Spatial intensity of dives To determine sites of notable foraging importance for seals, the numbers of dives occurring in 100m by 100m grid squares was counted (Figure 12a). In the majority of grid squares less than 10 dives occurred, however the grid scale of 100m by 100m is considered fine and so even fairly well used sites may appear to be less frequented. The scale was chosen to highlight the very heavily used areas, of which there are several. These are highlighted in Figure 12b, which has the low frequency areas removed. Notable areas of frequent dive activity include Selsey Bill, several areas within Chichester Harbour, the main channels of Langstone Harbour, Fareham Creek in Portsmouth Harbour and Lower Southampton Water around Calshot and Hythe. On the Isle of Wight frequently dived areas were Bembridge Ledges and Harbour and the sand flats off Ryde.

Figure 12a. Spatial intensity of dives where number of dives are aggregated in to 100 x 100m grid squares. © British Crown and SeaZone Solutions Limited. All rights reserved. Products Licence 032009.008.

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March 2010 37

Figure 12b. Spatial intensity of dives where dive frequencies between 0 and 10 per

To highlight differences in foraging behaviour, data for individual seals is presented in Figures 13a to e, it shows that the seals have their own preferred foraging areas: • pv26-01-09 feeds almost exclusively in Langstone and Chichester Harbours, it is the only seal to feed in the eastern side of Chichester Harbour around East Head and the Chichester Channel, which it does so extensively. • pv26-02-09 feeds primarily just inside the entrance to Chichester Harbour in the Emsworth Channel and Stocker Lake, it is also the only seal to feed at Bembridge Ledges on the Isle of Wight. • pv26-03-09 feeds frequently at more sites than any other tagged seal. It regularly feeds in Southampton Water, Chichester Harbour and Selsey Bill. It also feeds more extensively on the Isle of Wight than any other seal, mostly around Ryde, and further out towards the central Solent. • pv26-04-09 is very restricted in its feeding, focusing on a single area of shallow reef near Selsey Bill. • pv26-05-09 feeds most extensively in the Hampshire harbours, it is the only seal to feed repeatedly in Portsmouth Harbour.

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March 2010 39

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March 2010 40

The foraging ‘hotspots’ were looked at in more detail to determine if there was any obvious features that were attracting the seals to feed there . In some instances it did appear that there were physical features on the seabed that attracted the seals, presumably because they attracted fish. Figure 14 shows the foraging areas off Selsey Bill, which coincided with two shallow rocky reefs known as The Hounds and the Streets. Similarly, Figure 15 shows that the antisubmarine wall, built to help protect the Solent and Portsmouth Naval Base, also attracted repeat foraging dives.

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March 2010 41

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 42 In some areas however the number of dives could not be attributed to any notable sea bed feature and the seabed was charted to be relatively uniform sand or mud habitats (Figure 16).

Foraging was often concentrated around channels in the harbours where seals may have been attracted by fish moving in to and out of the harbours with the tides (Figure 17a & b).

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March 2010 43

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 44 3.3.6 Temporal foraging behaviour The tag data was examined to determine any temporal trends in foraging behaviour. For two seals, it did appear as if their foraging activity did change significantly over time. pv26-01-09 spent the first three weeks primarily in Langstone Harbour (Figure 18a), however, after this the foraging locations changed and significant amounts of time were spent foraging in Chichester Harbour, notably the eastern channels of Bosham and Itchenor (Figure 18b). Similarly, pv26-03-09 made repeated trips to the foraging grounds off Selsey Bill for the first seven weeks, after this the seal stopped visiting this area and switched to foraging in Southampton Water, an area it had not previously visited (Figure 19a & b).

Presumably these foraging pattern changes are related to prey availability and it is possible that the seals switch foraging locations at different times of the year to take advantage of aggregations of new prey species that may be related to migrations, spawning behaviour etc. It is possible that seal pv26-03-09 switched to feeding in Southampton Water and the River Test during the salmon smolt run, which occurs around this time.

It is possible that further temporal changes in foraging behaviour may occur during other times of the year when the animals were not tagged.

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March 2010 45

Figure 18a. pv26-01-09 foraging activity during the first three weeks of tag deployment (orange tracks).

Figure 18b. pv26-01-09 foraging activity during after the first three weeks of tag deployment (orange tracks).

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March 2010 46

Figure 19a. pv26-03-09 foraging activity during the first seven weeks of tag deployment (yellow tracks).

Figure 19b. pv26-03-09 foraging activity after the first seven weeks of tag deployment (yellow tracks).

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 47 3.3.7 Foraging ground surveys Some of the frequently used foraging grounds were surveyed using towed video to further highlight underwater features and any feeding habitat preference. Figure 20 shows the locations of the towed video surveys, based on the foraging grounds highlighted by the telemetry tag data.

In the Solent much of the seabed can be classified as mixed ground, being made up of patches of sand, gravel, shell and cobbles, this seabed type was much in evidence on these videos, however, it was possible to broadly categorise them further. Figure 21 shows that the most frequently foraged habitat consisted of mud, sand, gravel and shell (often Crepidula fornicata) typically hosting macroalgae and erect fauna, such as hydroids, bryozoans and sponges. The next most frequently visited habitat type was relatively clean mud and sand, where perhaps seals may have been targeting flatfish, which favour these areas. Both these broad habitat types were most frequently found in the harbours.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 48 Outside of the harbours, boulders, rocky reefs and hard substrates such as the submarine barrier were also targeted, notably towards Selsey Bill where several shallow (<5m) rocky reefs exist.

Potential prey species were very rarely sighted in the videos, this is not surprising as most mobile species are likely to move out of the way of the approaching camera sled.

The full list of sites with dominant habitat types is presented in Appendix 3.

9% 15% 7%

Bare mud / sand 69% Mud / sand / gravel / shell with erect fauna and macroalgae Gravel / shell / pebbles with erect fauna and macroalgae Cobbles / boulder / reef with erect fauna and macroalgae

Figure 21. Foraging habitat types recorded and categorised from the towed video surveys.

3.4 Conclusions

3.4.1 Summary Prior to the initiation of the Solent Seal Tagging project, very little was known about the harbour seal population that lived in the Solent area. This work provides the first detailed insight in to this population, improving our understanding of population structure, important haul-out sites and foraging areas. The use of the telemetry tags has been very successful and demonstrates their worth in gathering data on otherwise difficult to track animals.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 49 Key findings include: • Numbers of harbour seals in the area has slowly grown from an estimated 3 in 1994 to current numbers. • Number of harbour seals currently estimated at 23-25, with 18 being the most recorded at any one time. Being a small population makes them more vulnerable to impacts. • Number of grey seals estimated at two, it is not known if these are resident or transient. • Only two significant haul-out sites exist, one in Langstone and one in Chichester, making these sites particularly important and seals potentially vulnerable to disturbance as they do not have many other haul-outs to use if disturbed from their main sites. • Both haul-out sites are used on a more or less daily basis but Chichester Harbour is used by more seals. • The seals display often individual foraging behaviour and are faithful to their preferred foraging sites, making disturbance at these sites potentially significant. • The seals predominately forage in the Eastern Solent, between Southampton and Selsey Bill. • Seals regularly forage in the harbours, notably Portsmouth, Langstone, Chichester and Bembridge Harbours. • Seal foraging activity can change between seasons. • Seal foraging takes place in a variety of habitat types and can focus on discrete seabed features such as rocky reefs and underwater structures.

3.4.2 Further work The tags collect a large and varied amount of data and the analysis conducted as part of this study has only focused on specific aspects, those most relevant to the conservation and management of the seals and their important foraging and haul-out sites. Further work using the existing data sets could focus on other ecological and physiological parameters, examining foraging trip durations, dive depths and durations in terms of energetic efficiency. Further work on haul-out behaviour, such as relating it to tidal cycles and weather patterns would also be interesting.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 50 Gathering more data would also be very useful. Further public sightings will help to develop our understanding of seal foraging in the wider area and focused regular counts at haul-out sites will develop our knowledge of population sizes and potential growth. These counts should take place all year round with very regular counts during the breeding season to highlight pupping sites and population growth.

The photo identification work needs more attention, with more regular trips to photograph the seals, possibly using different equipment such as digital telescopes to get high resolution images from a distance so as not to disturb the seals. With a small population of seals it should possible to get accurate photographic records of each individual, which will help us monitor population changes and movements.

More focused prey analysis would also be useful in understanding the needs of the seal population. There are several ways of doing this, faecal collection and analysis for fish otoliths has been used in other areas, however searches for scat at Solent haulout sites have been negative. Now there is a better understanding of when and where the seals feed it may be possible to gather existing information from fish surveys, angling and commercial fishing records to look for trends in fish movements that explain seal foraging patterns.

Further tag deployments would also yield useful information. The data only illustrates behaviour of approximately 20 - 25% of the population. The seals often displayed individual behaviour so tagging other animals in the population may provide new, previously unknown information regarding foraging and haul-out behaviour. Tagging at different times of the year would allow behaviour exhibited between July and February to be highlighted, which may be quite different from that seen during this tagging period. No adult females were tagged as part of this project as none were caught, a more selective approach to capturing and tagging the seals may allow adult females to be tagged, which could illustrate breeding and pupping behaviour. It would also be very interesting to tag the grey seals in the area, this would allow us to examine the anecdotal evidence that they range further than the harbour seals, foraging around the Isle for Wight and the Western Solent, and prove if they are transient or resident.

Solent Seal Tagging Project Summary Report Wildlife Trusts’ South East Marine Programme

March 2010 51 Appendix I. Seal recording form for seal counters.

Solent Seal Recording Form. Please fill out one sheet per sighting event Phone number / Name email Date Time (from / to) Seen from boat / shore

Location of observer (inc Grid ref or Lat / Long) Location of seals (inc Grid ref or Lat / Long)

Sea state (circle) Number of seals seen Number of (leave blank is unsure) Slight Moderate Rough Grey Harbour Unknown Females Males Young (calm or (some (waves wavelets, waves few with lots of no whitecaps) whitecaps) whitecaps) Behaviour (put tally mark for each seal displaying each behaviour) Bottling (head bobbing in Flippering (waving Swimming Feeding / eating Hauled out Disturbed water) flipper) Other observations on behaviour (e.g. relaxed or watchful, vocalising, fighting, mating, prey species if feeding, disturbed by other seals or people, diving in from haulout)

Were photographs taken (if so please label with date and location and please group and label them so individual seals can be identified e.g. photos 1-5 relate to seal A, 6-8 seal B etc)

Other notes / observations (e.g. if hauled out on what - mud, pontoon, rock - types of disturbance, markings, patterns on seals) continue on separate sheet if necessary

Please return to Jolyon Chesworth, Marine Conservation Manager, Hampshire Wildlife Trust, Beechcroft House, Vicarage Lane, Curdridge, Hampshire, SO32 2DP.

Appendix II Solent Seal Tracking Programme Provisional Report March 2010

J. Christopher McKnight, Nicholas E. Fleming & Jonathan D.R Houghton School of Biological Sciences, Queen’s University Belfast

Page Background to study...... 2 Methods ...... 3 Provisional results ...... 5 Summary of key findings ...... 9 Figures ...... 10 Literature cited ...... 21

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1. Background to Study

Seals are not frequently seen in the Solent, however, a small but regionally significant population of common, or harbour seals (Phoca vitulina) live in and around Chichester Harbour. This population is unique, being the only one known to reside in the Eastern English Channel. Common seals feature in a number of conservation designations, including the Habitats Directive and Biodiversity Action Plans. Beyond this basic geographical knowledge, little is known about the common seals in Chichester Harbour.

Current monitoring efforts have provided some basic information as to their approximate numbers and preferred haulout sites. However, precise numbers, age classes, sex ratio’s, foraging and breeding areas are still largely unknown. Gaining a more robust knowledge of the seal population and their movements would allow their numbers and breeding success to be ascertained and their most important sites to be identified. It is also hoped to raise the awareness of harbour users to the presence of seals, and inform them of safe code of conduct around this important species.

With this remit in mind a tracking programme was established to reveal the temporal and spatial habitat usage of common seals in and around Chichester harbour. More broadly, we also aimed to produce a general overview of common seal behaviour in the Solent region that comprised the following information:

i. Areas of overall habitat usage and home ranges during foraging trips.

ii. Distance travelled during foraging trips

iii. Duration of foraging trips

iv. Rate of travel during foraging trips

v. Dive depth and water column usage

vi. The location of key haulout sites

vii. The haulout duration for each seal (total tracking period)

viii. Temporal shifts in haulout behaviour for each seal throughout total tracking period

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2. Methods

2.1 Study site, species and capture of study animals

Five harbour seals (four male and one female) were captured between 19th of March 2009 and 21st March 2009 at two haulout sites in the Solent, Hampshire, UK for the purpose of attaching GSM mobile phone tags. Deployments took place on three days in March 2009 (Table 1; see section 2.2. for details of instrumentation). Capture methods followed an established protocol used by the Sea Mammal Research Unit (SMRU), University on St. Andrews, using mesh nets and hoop nets. Upon capture, morphometrics were taken (weight, length and girth) to determine anaesthetic dosage for each individual, again following SMRU protocols.

2.2 GSM Mobile Phone Tags

The GSM phone tag incorporates the Global Systems for Mobile Communications (GSM) mobile phone technology as a method of sending high resolute behavioural data (McConnell et al., 2004). The major components of the tag are: a pressure sensor (resolution 5m at 2000m, 0.5m at surface), wet and dry salt water switch (to enable identification of periods out of water), a real time clock and a temperature sensor (resolution 0.1◦C). Continual monitoring of surface pressure, depth pressure and time allows for differentiation between separate behavioural states defined as; ‘diving’, ‘at the surface’ and ‘hauled out’. Diving is recorded when dive depth is deeper than 1.5 metres for more than eight seconds and ends when the subject animal surfaces to shallower than 1.5 metres. Further information on controlling software design to a specific host is detailed in McConnell et al. (2004). The GSM engine in the tag is a Siemens MC55/56 modem, which sends a short message service (SMS) of dive and haulout behaviour appended to a 160 character long buffer (Cronin and McConnell, 2008). To maximise battery utilisation when the buffer is full the data is saved to a SIM card in the tag and every four hours the tag ‘wakes’ from sleep mode and sends the saved data once the tag wet/dry sensor is dry. The tag is also fitted with an active GPS antenna calculating position from GPS satellites, latitude and longitude for each dive and haulout event is then encoded and transmitted with the data from the series of sensors inside the tag.

The GPS Phone Tags hardware is encapsulated in a solid epoxy body, measuring 100 x 70 x 40mm and weighs 210 g (in air) and was attached to the seals fur using epoxy resin (Cronin and McConnell, 2008). The dimensions and weight of the tag fell within acceptable guidelines of ethical practice, whereby the device represents <5% of the total body mass of the study animal (Cuthill 1991; Wilson and McMahon, 2006). The battery life of the GSM tags provided a theoretical longevity of approximately 6 months after which they detach from the animal during the annual moult (reference). The tag was attached to the fur at base of the skull to reduce interference by the host and increase likelihood of exposure from water at sea surface (facilitating data relay via GSM network) and to reduce drag (Wilson et al., 2004). 2.3.1 Habitat usage and home ranges during foraging trips

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The spatial coverage of common seal foraging trips was assessed using ArcGIS software to produce contour maps that encapsulated movements during the entire tracking period for each seal. Unfortunately, a software glitch in the GSM mobile phone tags rendered the GPS summary data frequently inaccurate. Consequently, spatial maps were based upon the coordinates (latitude and longitude) derived from the dive data, whereby the start and end of each dive was allocated its own coordinates. We then conducted a point pattern analysis in ArcGIS (also known as point pattern intensity) to assess areas where seal locations were most commonly obtained.

2.3.2 Distance travelled during foraging trips At the crudest level, two behavioural states were defined for the purpose of analysing foraging data; ‘hauled out’ and ‘foraging’. Foraging was defined as any period when the seal was not hauled out on land; encompassing both transiting and actual feeding behaviours. Distance travelled during a foraging period is typically calculated from the bespoke GPS positional summary generated by the GSM tag. However, as a result of the significant variance in the accuracy of the GPS positional summary produced by each tag, spatial patterns were again derived from the GPS locations of specific dives which wer found to be far more reliable. Distance travelled during a foraging trip was then calculated from the distance between subsequent GPS location on an identified foraging trip. The following equation provides a distance in kilometres between two locations:

ACOS(SIN(L1)*SIN(L2)+COS(L1)*COS(L2)*COS(Lg2‐Lg1))*6371

Where: L1 = Start latitude, L2 = End latitude, Lg2 = End Longitude, Lg1= Start Longitude

2.3.3 Mean and maximum duration of foraging trips

Foraging trip duration was taken as the time between two subsequent haulout periods. For each seal in turn, the duration of individual foraging trips was calculated to derive the mean trip duration (± SD) for that individual animal.

2.3.4 Mean and maximum rate of travel during foraging trips Mean rate of travel (speed) was calculated by taking the foraging distance (distance) and duration (time) and using the following equation:

Where: Speed = m.sec‐1, Distance = Kilometres, Time = Seconds 2.3.5 Dive depth

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Onboard software in the GSM phone tags examined the dive profile of a dive and determined the time and depth of the nine most significant points of inflection during the dive. The time and depth of these five points, along with the time of the start and end of the dive and dive duration, were then transmitted. This onboard data reduction meant that a large number of dive profiles could be relayed despite the limited buffer of the GSM relay system. The maximum point of inflection was taken as the maximum depth of a dive; consequently, mean depth as it is expressed here must be considered the mean of all the maximum depths recorded for all of the dives conducted by each individual seal.

2.3.6 The location of key haulout sites

Continual monitoring of surface pressure, depth pressure and time by the GSM tag allows for differentiation between separate behavioural states defined as; diving, at the surface and hauled out. A haulout event is classified as continually dry for ten minutes and ends when the tag is continuously wet for 40 seconds and is encoded with time of haulout start and end. Each haulout event was also encoded with GPS location. However, it was clear that the wet/dry sensors were not recording all haulout events. As a result of this slight glitch inferred haulout were additionally calculated from the time elapsed between dive events and geographical location. The temporal threshold adopted for the identification of an inferred haulout was taken to be the mean duration of ‘logged’ haulouts recorded by the on‐board sensor plus 1 standard deviation.

2.3.7 Mean and maximum haulout durations Haulout duration was simply calculated by subtracting the start time from the end time of a haulout event (logged and inferred). Mean and maximum haulout durations were then calculated for each seal over the entire tracking period. To investigate temporal shifts in haulout behaviour throughout the tracking period we also considered the data month by month. NB: If a haulout event ends in a different month than which it began, the duration of haulout was totalled with the durations for the month in which the haulout began.

3. Provisional Results

3.1 Deployment duration

The overall tracking duration for each seal is summarised in Table 1, with the longest deployment duration being 123 days (Seal 3) and the shortest 73 days (Seal 2). Mean deployment duration was 98.4 days (SD±19.7); approximately 3.2 months.

Table 1: Overview of GSM deployment and duration of tracking period

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Deployment Capture Age Deployment Tracking Seal # Reference # Sex site Method status date duration (days) 1 pv26‐01‐09 1 net male adult 19‐03‐2009 93

2 pv26‐02‐09 2 hoop net male adult 18‐03‐2009 73

3 pv26‐03‐09 1 net male adult 19‐03‐2009 123

4 pv26‐04‐09 2 net female juvenile 19 ‐03‐2009 90

5 pv26‐05‐09 2 net male adult 21‐03‐2009 113

3.2.1 Habitat usage and home ranges during foraging trips The spatial coverage of foraging trips in its simplest form is given in Fig.1. Areas between Portsmouth Harbour, Langstone Harbour and Chichester Harbour displayed the greatest intensity of seal activity. Seals 2, 3 and 5 made frequent crossings between the English mainland and Isle of Wight. Only seal 3 travelled further west than Portsmouth Harbour, travelling as far west as Southampton (50.8966oN, 1.42245oW; eastern‐most point of travel). Seal 5 was the only seal in the deployment to travel further east than Pagham Harbour, travelling as far as Shoreham Beach (50.77oN, 0.22oW; western‐most point of travel). The southern‐most point of travel was south east of the Isle of Wight (50.233◦N; 0.549◦W) (seal 5).

The same data are presented in a different manner in Fig 2. This representation constitutes a first‐order analysis based upon intensity (or the mean number of events per unit area) at a given location. Second‐order effects (spatial dependence) refer to the relationship between paired events in the study region (this will be conducted over the next month by combing GPS coordinates with dive data). The maps generated for this provisional report represent the number of events (in this case aerial exposure of the GSM tag) in an area. From a management perspective the salient point here is that these maps represent a density estimation of when the seals were actually at the surface, which in turn may either increase or decrease (as boat uses may spot and avoid the seals) incidents of boat strike.

3.2.2 Distance travelled during foraging trips

Table 2 provides an overview of mean and maximum distance on foraging trips for each seal. Mean foraging distance varied by only a few kilometres between seals 1, 4 and 5. However, mean foraging distance of seal 3 was greater than that of any other seal (34.88 km ±21.649) while seal 2 displayed the lowest mean foraging distance (9.29km ±10.894).

2.3.3 Duration of foraging trips

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The mean durations of forging trips for each seal are again given in Table 2. The mean duration of foraging trips varied between 10.07 (± 14.23) for seal 5 and 15.53 (± 19.95) for seal 3 with a maximum recorded duration of 108.48 hours (seal 3). Nonetheless, an Analysis of Variance (ANOVA) revealed that these apparent differences between individuals were not significantly different (p>0.05).

2.3.4 Rate of travel during foraging trips

Summarised in Table 2, the mean rate of travel between seals varied significantly during foraging trips (ANOVA; p< 0.05). Seal 3 had the greatest mean rate of travel (0.85 m/s; SD±0.33), while seal 2 had the lowest mean rate of travel (0.36 m/s; SD±0.31).

2.3.5 Dive depth

A total of 156,604 dives were recorded for all seals over a combined tracking period of 600 days. Dive depths were heavily skewed towards shallow water with 85% of events occurring in the top 5 metres and 97% in the top 10 m (Fig 3). A normality test (Kolmogrov‐Smirnov, p<0.001) confirmed that the data were not evenly distributed. A Kruskal Wallace test was used to test for differences in the central tendency in dive depths (i.e. median) revealing no significant difference between any of the seals. These data are shown in Fig. 4 showing the median, inter‐quartile range and 5 and 95% outliers.

Table 2: A summary of foraging trip distance and duration and dive depths

Mean Max. Mean Mean Rate of Mean Max Max Rate of Dive Seal Ref Duration(h) Travel Distance (km) Distance D (m)* Duration(h) Travel Depth max (SD) (m/s)(S (SD) (km) (m/s) (m) (SD) D) 14.35 0.59 17.808 3.31 Pv26_01_09 1.33 82.31 23.2 (±18.60) 82.5 2 (±0.21) (±14.745) (±1.90)

11.63 0.36 3.59 Pv26_02_09 70.50 1.54 9.293(±10.894) 56.14 35.2 (±13.63) (±0.31) (±2.80)

15.53 0.85 34.878 3.82 Pv26_03_09 108.48 1.95 98.99 34.8 (±19.95) (±0.33) (±21.649) (±2.88)

12.73 0.61 19.811 2.68 Pv26_04_09 35.25 1.06 47.75 14.8 (±7.50) (±0.24) (±11.273) (±2.81)

10.07 0.60 16.468 3.59 Pv26_05_09 15.08 1.24 161.08 59.4 (±14.23) (±0.31) (±23.986) (±3.17)

* Dmax = maximum depth recorded during tracking period 2.3.6 The location of key haulout sites

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From a conservation and management perspective, the identification of principal seal haulout sites is a top priority. All haulout sites were situated between Hayling Island and Chichester Channel; with the two main haulout sites accounting for 95.8% of haulout events (logged and derived) over the deployment period. Haulout site 1 accounted for 29.5% (n=98) of all haulout events and site 2 accounted for 66.27% (n=220). There was however, no appreciable difference in mean haulout duration between sites 1 and 2 (t‐test; p>0.05).

2.3.7 Haulout duration

The haulout behaviour of the five seals is summarised in Table 3. Seal 4 had the shortest mean haulout duration (2.34 h; ±1.58) while seal 1 had the longest mean haulout period (4.19 h; ±2.17). Analysis of Variance revealed that mean haulout durations were not significantly different between seals (p>0.05) (Fig. 5).

To investigate temporal patterns in haulout behaviour for individual seals, we categorised the data into separate months (Fig. 6). For all seals monthly haulout duration remained relatively constant from March until July (where tag remained attached and functioning).

Table 3: Summary of haulout behaviour

Logged (& inferred) Mean haulout duration Max haulout duration Seal ref # haulouts (h) (SD) (h)

Pv26_01_09 188 (15) 4.19 (±2.17) 14.24

Pv26_02_09 78 (27) 4.13 (±2.17) 11.31

Pv26_03_09 202 (10) 4.13 (±2.43) 19.55

Pv26_04_09 198 (22) 2.34 (±1.58) 08.20

Pv26_05_09 246 (34) 3.55 (±2.40) 12.17

Summary of key findings

• The longest duration of a GSM tag deployment was 211days (Seal 3) and the shortest 74 days (Seal 2). Mean deployment duration was 126.6days (SD±53.9); approximately 4.2 months.

• During foraging trips the areas between Portsmouth Harbour, Langstone Harbour and Chichester Harbour displayed the greatest intensity of seal activity. Seals 2, 3 and 5

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made frequent crossings between Hampshire and Isle of Wight. Only seal 3 travelled further west than Portsmouth Harbour, travelling as far west as Southampton. Seal 5 was the only seal to move further east than Pagham Harbour, travelling as far as Shoreham Beach .The southern‐most point of travel was southeast of the Isle of Wight (50.233◦N; 0.549◦W) (seal 5).

• The mean rate of travel between seals varied significantly during foraging trips. Seal 3 had the greatest mean rate of travel (0.85 m/s; SD±0.33), while seal 2 had the lowest mean rate of travel (0.36 m/s; SD±0.31).

• The mean duration of foraging trips varied between 10.07 (±14.23) for seal 5 and 15.53 (±19.95) for seal 3 with a maximum recorded duration of 108.48 hours (seal 3). However, there were no significant difference between seals in terms of foraging trip duration.

• A total of 156,604 dives were recorded for all five seals over a combined tracking period of almost 500 days.

• Dive depths were heavily skewed towards shallow water with 85% of events occurring in the top 5 metres and 97% in the top 10 m.

• All haulout sites were situated between Hayling Island and Chichester Channel; with the two main haulout sites accounting for 95.8% of haulout events. Haulout site 1 accounted for 29.5% (n=98) of all haulout events and site 2 accounted for 66.27% (n=220). There was however, no appreciable difference in mean haulout duration between sites 1 and 2.

• Seal 4 had the shortest mean haulout duration (2.34 h; ±1.58) while seal 1 had the longest mean haulout period (4.19 h; ±2.17). However, haulout durations were not significantly different.

• For all seals monthly haulout duration remained relatively constant over the deployment period.

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(a) (b)

Fig ?? (b) Foraging tracks seal 1 (pv26‐01‐09)

(e) (f)

Fig. 1: Raw tracking data showing complete foraging tracks for entire duration of GSM tag deployments for (a) all seals (b) seal 1 pv26‐01‐09; (c) Seal 2 pv26‐02‐09; (d) seal 3 pv26‐03‐09; (e) seal 4 pv26‐04‐09; (f) seal 5 pv26‐05‐09. Lines over land do not represent erroneous movements but are simply an artefact of the data in their raw form. all subsequent locations are joined by a straight line so when a seal moves from bay to bay without intermediate locations being available the track appears to cross the land.

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Fig 2: Arc‐GIS plots showing the number of GPS locations received as a proxy for levels of activity in different areas. These maps represent a density estimation of when the seals were actually at the surface.

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Fig. 2 (continued) showing Arc‐GIS plots for seals 3 and 4

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Fig. 2 (continued) showing Arc‐GIS plots for seals 5

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Fig 3: Frequency histograms showing the depth of dives conducted by each seal classified into 5 metre depth bins

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Fig. 4: Box plots showing the median and inter‐quartile range of for the depth of dives conducted by each seal. Black circles show the 5th and 95th percentile (i.e. the range between these two points encapsulates 90% of all the recorded depths)

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Fig. 5: Mean haulout duration (logged and inferred) (± 1 SD) for each seal over the entire tracking period.

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individual Fig Page

Mean haulout duration (hours) (+/- 1SD) Mean haulout duration (hours) (+/- 1 SD) Mean haulout duration (hours) (+/- 1SD) 10 10 10 0 2 4 6 8 6: 0 2 4 6 8 0 2 4 6 8

C (Seal 3) A (Seal 1) E (Seal 5) 17 Mean

months a p a ueJuly June May Apr Mar

haulout throughout

Month duration

the

(logged

tracking

and

period.

inferred)

D (Seal 4) B (Seal 2) a p a ueJuly June May Apr Mar (±

SD)

Month for

each

seal expressed

Literature cited:

Cronin M. A. and McConnell B. J. (2008). SMS seal: A new technique to measure haul‐out behaviour in marine vertebrates. Journal of Experimental Marine Biology and Ecology 362, 43– 48.

Cuthill I. (1991). Field experiments in animal behaviour: methods and ethics. Anim. Behav 42, 1007–1014.

McConnell B.J., Beaton R., Bryant E., Hunter C., Lovell P. and Hall A. (2004). Phoning home— a new GSM mobile phone telemetry system to collect mark‐recapture data. Mar. Mamm. Sci. 20(2), 274–283.

Wilson R. P. and McMahon C. (2006). Measuring devices on wild animals: what constitutes acceptable practice? Front Ecol Environ 4(3), 147‐154.

Wilson R. P., Scolaro J. A., Quintana F., Siebert U., Thor‐Straten M., Mills K., Zimmer I., Liebsch N., Steinfurth A., Spindler G. and Müller G. (2004). To the bottom of the heart: cloacal movement as an index of cardiac frequency, respiration and digestive evacuation in penguins. Mar Biol 144, 813–27.

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Appendix III. Towed video survey locations and habitat descriptions.

Site Start Lat Start Long Stop Lat Stop Long Structures Habitat Description

1 50.80853 0.866192 50.80853 0.866192 Pontoon Muddy sediment with shell gravel. High coverage of Crepidula with some erect hydroids and sponges

2 50.80866 0.864465 50.8087 0.864443 Moorings Muddy sediment with shell gravel and oyster shells. Heavily encrusted shells and erect hydroids and sponges. Ascidians.

3 50.80519 0.856447 50.8052 0.856382 Moorings Muddy sediment with shell gravel and oyster shells. Shells heavily encrusted with fauna and erect hydroids and sponges.

4 50.81018 0.853723 50.81019 0.870467 Moorings Muddy sediment with high level of Crepidula cover. Oyster shells encrusted and some erect sponges present

5 50.78579 0.931957 50.78561 0.931908 None Clean sand with ripples. Macroalgae detritus

6 50.78779 0.932055 50.78766 0.932105 None Muddy Sand with shell grave. Dense bed of ?Alcionidium diaphinum?

7 50.78737 0.934315 50.78722 0.933975 None Shell and shell gravel. Sparse faunal turf.

8 50.81499 1.002073 50.81506 1.002095 None Muddy sand with shell gravel. Crepidula, erect and encrusting fauna

9 50.82216 0.99959 50.82191 0.999622 None Muddy sand with shell gravel. Dense Crepidula. Erect and encrusting fauna and occasional macroalgae.

10 50.82471 0.998585 50.8246 0.998428 None Muddy sand, shell gravel with Crepidula and encrusting and occasional erect fauna

11 50.83032 0.998603 50.83033 0.998317 None Muddy sand, shell gravel with encrusting and dense erect fauna and macroalgae on shells

12 50.83032 0.974365 50.82838 0.990827 None Mud and silt

13 50.83013 0.994603 50.83002 0.994637 None Mud/silt with erect macroalgae and fauna attached to shell material

14 50.83437 0.988557 50.83429 0.988307 None Mud and silt with buried shell material. Occasional macroalgae and fauna Site Start Lat Start Long Stop Lat Stop Long Structures Habitat Description

15 50.83468 0.961342 50.83455 0.96087 None Rich site with dense erect fauna and macroalgae.

16 50.83283 0.955712 50.8328 0.955293 None Rich site with dense erect fauna and macroalgae.

17 50.83058 0.953133 50.83046 0.952758 None Muddy silt with shell gravel. Erect macroalgae and fauna. Sargassum.

18 50.83036 0.952952 50.83001 0.952613 None Muddy silt with shell gravel. Erect macroalgae and fauna. Sargassum

19 50.83348 0.942557 50.83333 0.942683 None Muddy silt with shell gravel. Erect macroalgae. Sargassum

20 50.80375 0.850303 50.80373 0.850355 None Rich site with dense encrusting and erect fauna and macroalgae.

21 50.80294 0.846668 50.80298 0.846697 None Muddy silt and sand. Rich encrusting and erect fauna on oyster shells.

22 50.73678 1.152468 50.73705 1.152552 None Eelgrass bed (?Zostera noltii?), sandy sediment. Variety of encrusting fauna.

23 50.74123 1.15169 50.7417 1.151503 None Sandy sediment with shell material. Macroalgae attached to shell. Macroalgal detritus. Possible eelgrass (poor visibility)

24 50.74412 1.140708 50.74422 1.141205 None Sandy sediment with shell material. Macroalgae attached to shell. Macroalgal detritus. Possible eelgrass (poor visibility)

25 50.73691 1.129343 50.7373 1.12986 None Sandy sediment with some shell material. Sparse macroalgae attached to shell. Macroalgal detritus.

26 50.73673 1.120722 50.73697 1.121388 None Sandy sediment with some shell material. Sparse macroalgae attached to shell. Macroalgal detritus.

28 50.69423 1.097325 50.69424 1.097198 None Firm sand and pepples/shingle. Diverse attached macrofauna.

29 50.69618 1.09504 50.69637 1.095212 None Sandy sediment with some shell material. Sparse macroalgae attached to shell. Macroalgal detritus.

30 50.70111 1.096967 50.70137 1.096965 None Gravely sand with erect fauna and macroalgae Site Start Lat Start Long Stop Lat Stop Long Structures Habitat Description

31 50.70538 1.089968 50.70544 1.089827 None Patchy Sand and gravel/pebbles. Burrows/siphon holes visible in sandy areas. Dense erect fauna and marcroalage on harder ground patches

32 50.75613 1.06754 50.75623 1.068388 Submarine Dense macroalgae cover Barrier

33 50.7613 1.068415 50.76121 1.068353 Submarine Dense macroalgae cover Barrier

34 50.7941 0.90045 0 0 None Sandy sediment with shell material. Erect fauna and macroalgae attached to shell. Macroalgal detritus.

35 50.79178 0.90045 50.79165 0.9052 None Muddy sand with shell gravel. Patches of dense Crepidula. Erect and encrusting fauna. Occasional macrofauna.

36 50.79037 0.908933 50.79312 0.90655 None Muddy sand with shell gravel. Erect and encrusting fauna and macroalgae

37 50.79288 0.907083 50.79345 0.90575 None Muddy sand dense Crepidula. Macrofauna.

38 50.79222 0.9175 0 0 None Clean sand with ripples, detritus

39 50.79105 0.92725 50.79145 0.927283 None Muddy sand with erect fauna and macroalgae. And a fish!

40 50.79038 0.938067 50.79092 0.938333 None Clean sand with ripples, detritus

41 50.79265 0.938433 0 0 None Clean sand with ripples, detritus, patches of shell with macroalgae

42 50.79978 0.940167 50.78945 0.940967 None Muddy sand, Crepidula, macroalgae

43 50.80447 0.94405 50.80507 0.944133 None Muddy sand with shell gravel. Erect and encrusting fauna and macroalgae

44 50.80708 0.9434 0 0 None Muddy sand with shell gravel. Crepidula, erect and encrusting fauna

45 50.81115 0.94355 50.81158 0.943683 None Muddy sand with shell gravel. Erect fauna and macrofauna Site Start Lat Start Long Stop Lat Stop Long Structures Habitat Description

46 50.81315 0.9476 50.81553 0.9478 None Sa ndy sediment and detritus

47 50.74572 0.855917 50.74558 0.855133 Pots Muddy sand, boulders with encrusting and erect fauna. Macroalgae. Fish (Pouting)

48 50.74552 0.8455 50.74555 0.844567 Pots Rock boulders and reef with encrusting and erect fauna and macrofauna.

49 50.74437 0.842733 50.74435 0.841183 None Clean sand with some shell material. Sand ripples.

50 50.74338 0.835083 50.74347 0.834433 None Rock boulders and reef with encrusting and erect fauna and macrofauna. Areas of sand and gravel.

51 50.7353 0.830733 50.73522 0.8305 None Rock boulders and reef with dense macroalgae cover. Encrusting and erect fauna.

52 50.7144 0.8215 50.71492 0.81815 None Rock reef of limestone slabs with erect and encrusting fauna and macrofauna

53 50.7201 0.8156 50.72342 0.806 Pots Sand ripples and detritus with patches of cobble/pebbles with macroalgae attached.

54 50.7237 0.813267 50.72405 0.8105 None Rock boulders and reef with encrusting and erect fauna and macrofauna. Areas of sand and gravel.

55 50.72323 0.806583 50.72342 0.806 None Sand ripples

56 50.72048 0.802 50.72102 0.801617 None Pebbles and shells with boulders and cobbles. Erect macroalgae and fauna.

57 50.78953 1.027567 50.79043 1.027733 None Shingle and pebbles with sparse erect fauna and macroalgae

58 50.79042 1.027867 50.79053 1.028 None Shingle and pebbles with sparse erect fauna and macroalgae

59 50.79542 1.0276 50.79757 1.02755 None Deep shingle (15 m) encrusting fauna

60 50.80253 1.028683 50.79912 1.02865 None Muddy sediment with dense Crepidula and shell gravel

61 50.80303 1.030533 50.8035 1.030267 None Sand ripples Site Start Lat Start Long Stop Lat Stop Long Structures Habitat Description

62 50.80575 1.030783 50.806 1.0303 None Muddy sand with shell gravel and detritus

63 50.8117 1.029 50.81138 1.029583 None Sand ripples and detritus with patches of cobble/pebbles with macroalgae attached.

64 50.81542 1.03285 50.81512 1.033617 None Muddy sand and shell material with attached macroalgae

65 50.82012 1.036317 50.81935 1.03665 Cables Muddy sand and shell material. Old cables/chains from moorings with attached macroalgae

66 50.80673 1.019317 50.80703 1.019817 None Muddy sand with dense Crepidula cover

67 50.79357 0.9047 0 0 None Muddy sand with dense Crepidula cover

68 50.79168 0.9122 50.79417 0.903 None Muddy sand with dense Crepidula cover