Status of Balearic Shearwater, White-beaked Dolphin and other marine animals in Lyme Bay and surrounding waters

Transcription

1 Status of Balearic Shearwater, White-beaked Dolphin and other marine animals in Lyme Bay and surrounding waters Tom Brereton 1, Russell Wynn 2, Colin MacLeod 1, Sarah Bannon 1, Becky Scott 1, Jo Waram 1, Kate Lewis 1, James Phillips 3, Clive Martin 1, Roger Covey 3 1 Marinelife, 2 SeaWatch SW, 3 Natural England Marinelife St Andrews Road, Bridport, Dorset May 2010 `

2 Table of contents Summary Introduction Objectives Policy relevance to Natural England Study area Habitat and fisheries Baseline offshore effort-related surveys Kerr-McGee study and SCANS II Focal species Balearic Shearwater Conservation status Range & population Life cycle Diet White-beaked Dolphin Protection measures Distribution Behaviour and social structure Abundance Diet Recent distribution shifts Methods Opportunistic surveys Natural England surveys Land-based counts of Balearic Shearwater Overlaying sightings with environmental data Stakeholder engagement Results Balearic Shearwater Effort-related observations from sea Land-based counts Balearic Shearwaters in Lyme Bay prior to Balearic Shearwaters in Lyme Bay in White-beaked Dolphins in Lyme Bay Sightings between 2006 and Co-occurrence with other cetacean species Association with seabirds Other recent records of White-beaked Dolphin in the Channel Photo-Identification catalogue Other seabirds recorded in Lyme Bay Other cetaceans seen recorded in Lyme Bay Effort related sightings Casual sightings Stakeholder engagement Postcard distribution Fishermen impacted by the ban on scallop dredging Discussion Importance of Lyme Bay for Balearic Shearwater Possible reasons why Portland is important for Balearic Shearwaters 44 2

3 6.3 Importance of Lyme Bay for White-beaked Dolphin Possible reasons why Lyme Bay is utilised by White-beaked Dolphin Recommendations for future work Repeat Natural England funded transect surveys/further analytical work Targeted surveys for White-beaked Dolphin and Balearic Shearwater Investigating ecology of Balearic Shearwaters through satellite telemetry Acoustic monitoring of White-beaked Dolphins in Lyme Bay Developing a Lyme Bay Wildlife Officer post Extending White-beaked Dolphin work beyond south-west England References Acknowledgements Appendices 55 List of Tables, Figures and Appendices Figure 2.1: Sediments of Lyme Bay and surrounding waters (taken from Poulton et 11 al 2002). Figure 2.2: The location of fronts and mixing properties of Lyme Bay and 11 surrounding waters (Source Maddock et al. 1981) Figure 2.3: The Shambles Bank off Portland Bill. (Source Pingree 1978) 12 Figure 2.4: Distribution of main fishing activities in Lyme Bay on sightings from the 12 DSFC patrol vessel (Source: University of Plymouth) Figure 3.1: Breeding distribution (pink circles) of Balearic Shearwater in the 14 Mediterranean (Source: European Bird Census Council) Figure 3.2: White-beaked Dolphin global distribution (Source: adapted from 17 Cawardine, 1995). Figure 3.3: Distribution of White-beaked Dolphin around the British Isles. 18 Figure 3.4: Location of White-beaked Dolphin stranded around the UK and Ireland 19 by region (black lines). Figure 3.5: SCANS II abundance estimates for White-beaked Dolphin. (Source: 20 Hammond and MacLeod 2006). Figure 4.1: Effort-related surveys in Lyme Bay (red = NE funded surveys 23 in 2009, green = other) Figure 4.2 Dolphin and shearwater postcard surveys 24 Figure 4.3 Data entry and reporting functionality of new web pages to capture 25 sightings from local skippers and members of the public Figure 5.1: Balearic shearwaters recorded in Lyme Bay from effort-related and 26 casual surveys. Figure 5.2: Temporal distribution of Balearic Shearwater records in Lyme Bay 27 during Figure 5.3: Monthly sightings of Balearic Shearwaters in Figure 5.4: Monthly sightings of Balearic Shearwaters in Figure 5.5: White-beaked dolphins recorded in Lyme Bay from effortrelated surveys and casual records. 30 Figure 5.6: Water temperatures in 1-km squares where White-beaked Dolphins 32 were recorded Figure 5.7: Cetacean sightings in months when white-beaked dolphins were 33 recorded in Lyme Bay Figure 5.8: Cetacean sightings in months when white-beaked dolphins were not 33 recorded in Lyme Bay

4 Figure 5.9: Casual sightings of White-beaked Dolphin post 1985 (excluding Lyme 34 Bay records post-2005) Figure 5.10: European Storm-petrels recorded in Lyme Bay from effort-related and 35 casual surveys.. Figure 5.11: Great Skuas recorded in Lyme Bay from effort-related and casual 37 surveys during the summer months Figure 5.12: Great Skuas recorded in Lyme Bay from Natural England effort-related 38 and casual surveys in the early winter period Figure 5.13: Distribution and relative abundance of Guillemots in Lyme Bay on 39 Natural England surveys during the early winter period in Figure 5.14: Harbour Porpoise effort-related sightings from Marinelife surveys in 40 Lyme Bay during the summer (Apr-Sep) and winter (Oct-Mar) months Figure 5.15: Cetacean sightings on monthly Kerr-McGee transects in Left 41 side - Bottlenose Dolphin, Right side Harbour Porpoise (Source: Leaper et al. 1995). Figure 5.16: Casual sightings of cetaceans in Lyme Bay in 2009 obtained through 41 the Natural England project. Figure 5.17: Location of ports (yellow crosses) where postcards have been 42 distributed to local skippers Figure 5.18: Location of sailing clubs (yellow crosses) where postcards have been 42 distributed to local skippers... Figure 6.1: Elevated Total Suspended Matter concentrations (a turbidity measure) 45 concentrations off Portland Bill in early July (Source: Plymouth Marine Lab) Figure 6.2: The proportion of sightings of each species in 1 o C temperature classes 47 for summer months from Table 4.1: Effort-related surveys in Lyme Bay and surrounding waters Table 5.1: Monthly summary of Balearic Shearwater sightings 23 Table 5.2: Monthly summary of White-beaked Dolphin sightings 31 Table 5.3: Seabird sightings in Lyme Bay seen on Natural England surveys from 36 February to April 2009 Table 5.4: Effort related cetacean sightings in Lyme Bay Appendix 9.11: Balearic shearwaters recorded in the English Channel from survey 55 and casual effort. 4

5 Summary Lyme Bay is an ecotone which supports both warm waters species of the south west and colder water species of the North Sea and eastern Channel. Habitat and species variety is high and the area is well known for the occurrence of a number of rare species of lower trophic levels, including sea slugs and sea fans associated with reef habitats. Seabirds and cetaceans are well monitored from coastal watchpoints, with important species regularly occurring including Bottlenose Dolphin, Harbour Porpoise and Balearic Shearwater. Sightings of Balearic Shearwater are collated annually by SeaWatch SW. The offshore status of seabirds and cetaceans is less well known. There are surprisingly few casual records of cetaceans (Peter Evans pers. comm.) and only two systematic scientific surveys have been carried out, with the inner Bay sampled for seabirds and cetaceans in 1994/95 (Kerr McGee Oil) and the outer Bay for cetaceans in 2005 (SCANS 2). There is a pressing need for offshore sightings data and interpretation of both offshore and land-based sightings data to inform the identification of candidate Marine Protected Areas (MPAs), Special Areas of Conservation (SACs) (e.g. for Harbour Porpoise) and Special Protection Areas (SPAs) (e.g. for Balearic Shearwater). In 2007, the conservation and research charity Marinelife, in collaboration with the RSPB and SeaWatch SW, established a programme of cetacean and seabird surveys in the offshore waters of Lyme Bay, focussed on Balearic Shearwater. The principal aim being to provide to inform the selection of protected areas, whilst understanding the prey items and feeding distribution of Balearic shearwaters is a requirement of the European Action Plan for the species. The surveys detected a wide diversity of cetaceans and seabirds in Lyme Bay. Of particular significance were regular sightings of two focal species - Balearic Shearwater and White-beaked Dolphin. A number of White-beaked Dolphins had unique markings, highlighting the potential to develop a photo-identification catalogue for this species. In view of the interest found, a programme of community engagement was established to encourage and collate casual records from local skippers and other recorders, with encouraging results (e.g. bringing in new sightings data that were not being captured elsewhere). In 2009, a wide-ranging project was established with Natural England to synthesise Marinelife and SeaWatch SW information on Balearic Shearwater, White-beaked Dolphin and other marine animals in Lyme Bay to inform future conservation strategies and to continue to develop the programme of public and local skipper engagement. Specific project objectives included (1) to carry out a systematic winter survey of Lyme Bay for Balearic Shearwater and White-beaked Dolphin (2) to assess the status of these two focal species in Lyme Bay (3) to develop and publish Marinelife s photo-identification catalogue of Whitebeaked Dolphin and other cetaceans (4) to develop the local skipper engagement work and assess opportunities (e.g. eco-tourism) for fishermen impacted by the ban in Lyme Bay on scallop fishing and bottom trawling and (5) to suggest future policy relevant research and engagement work. In an effort to increase the number of records submitted by the public, a postcard survey was launched for Lyme Bay dolphins and shearwaters and a website established to enable online submission and reporting of data. The postcards were distributed to 185 skippers of angling, diving and leisure boat trips and 44 Sailing Clubs southwest England. 5

6 Balearic Shearwater is Europe s rarest seabird and is classified as globally and critically endangered by the IUCN. It is threatened by alien species, overfishing, drowning in fishing nets and human disturbance. White-beaked Dolphin is a UK BAP Priority species (Grouped plan for small dolphins) and is suspected to be declining in the southern parts of its range in UK waters. It is threatened by climate change and over-fishing. In this report we analyse the status of Lyme Bay of Balearic Shearwater and White-beaked Dolphin from ~4800km of effort-related offshore surveys (n=~50), and from casual records including ~500 land-based Balearic Shearwater records collated over 2007/8 by SeaWatch SW. Analysis of land-based records collated by SeaWatch SW indicate that in recent years internationally important numbers of Balearic Shearwaters have visited Lyme Bay, with the area regularly holding a third of the annual UK and Irish sightings total. Three-figure counts of Balearic Shearwaters have regularly been made in recent years, indicating that up to 0.5% of the World population may be present in Lyme Bay at any one time. There are also indications that numbers utilising Lyme Bay, and southwest UK in general, are increasing, probably in response to climate and fisheries-driven changes in prey availability. The number of birds utilising Lyme Bay show marked inter-annual variability (e.g. 50% fewer in 2008 than 2007), probably in response to local changes in prey distribution. Birds principally occur between June and October, although winter sightings are increasing. A key issue is how Balearic Shearwaters utilise Lyme Bay and whether the majority are (1) seasonally resident birds utilising the Bay to feed and moult or (2) wind-driven birds temporarily displaced from core areas further south or (3) wind assisted birds, undertaking large-scale foraging movements in favourable weather conditions. Available land-based and at-sea sightings data indicate that the waters within a few miles of Portland Bill are regularly used by important numbers of moulting/foraging birds in some (but not all) years. In 2007, a minimum of 0.5% of the global population was thought to be foraging off the Bill area over the late June/early July period with smaller numbers through the summer. Portland Bill may be an important foraging area for Balearic Shearwater because (1) local conditions can (in some years) support the development of concentrations of key prey items including Anchovy, other shoaling fish and plankton(2) the area (especially the Shambles Bank and Portland Race ) is relatively heavily fished and provides enhanced opportunities for scavenging. Away from Portland Bill, no significant at-sea concentrations have yet been found and in the central parts of Lyme Bay birds have only been found in extremely low densities (widely dispersed in ones and twos), usually scavenging around angling and fishing boats. As has been demonstrated in the Mediterranean, scavenging is similarly thought to be a key foraging strategy in Lyme Bay. There may be hotspots that have yet to be discovered, especially in under-sampled inshore areas of the western Bay between Beer and Prawle. However, the paucity of offshore records and the correlation between high counts from land and periods of fresh winds from the south/west, suggests that that the bulk of birds seen on a number of the high count days are likely wind-driven (or wind assisted) birds from further south (e.g. coast of north west France) that exit Lyme Bay equally rapidly. Thus high day counts from land can give a false impression of how many birds are regularly utilising Lyme Bay to moult and feed over the summer months. (Stop press this was confirmed later in 2009, when 1000 birds were recorded summering in the Bay de St Brieuc on the north Brittany coast west of St Malo). 6

7 From July 2006 to April 2009 twenty sightings of ~300 individual White-beaked Dolphins were recorded in a relatively restricted part of Lyme Bay, with nine of the sightings on effortrelated surveys. Sightings have been made in all months except December (no survey effort) and February (thought to be absent in 2009). On effort-related surveys, White-beaked Dolphins were the second most frequently seen cetacean species after Harbour Porpoise, accounting for approximately a fifth of all sightings. With additional sightings made in 2005 and (stop press) again in 2009, Lyme Bay can now be identified as the most southerly known site in Europe where the species regularly occurs. Up to 200 animals have been seen, which represents ~1% of the total population estimated for north-west European shelf waters, confirming regional and possibly national importance. Lyme Bay may be the most important locality in the English Channel for White-beaked Dolphin, though this cannot be confirmed due to under-sampling of other areas. The species is extremely rare in other well-recorded areas of the Channel (e.g. off the Normandy coastline). The core area of White-beaked Dolphin occurrence is central Lyme Bay which has a number of features that are thought to be important in determining presence and concur with results from the few studies completed on this dolphin species in other parts of the UK. These include (1) Water depths of >50m (2) Stratification of the water column in the summer (3) A gently sloping, predominantly sandy seabed (4) Plentiful stocks of Cod and Whiting (key known prey items), especially in the summer (5) An absence of Common Dolphin in the summer months (6) A general absence of Bottlenose Dolphin and (7) Sea surface temperatures below 18 C. The long-term conservation of White-beaked Dolphin in Lyme Bay is a cause of conservation concern due to predicted rises in sea surface temperature (SST). White-beaked Dolphin rarely occurs in waters >18ºC and currently waters temperatures regularly reach ºC in Lyme Bay in the summer months. A catalogue of uniquely marked White-beaked Dolphins (n=6) and Bottlenose Dolphins (n=24) photographed in Lyme Bay and surrounding waters was established under the project. The catalogue can be downloaded from Over the ~50 effort-related surveys between 2007 and 2009 there were 4250 seabird sightings totalling 43,200 birds of 33 species. 15,530 birds of 30 species were recorded on the nine Natural England surveys from February to April Seabird highlights from the surveys included: (1) Large numbers of Guillemots and Razorbills widely distributed across Lyme Bay in February Crude abundance estimates of 16,000 Guillemots and 4,000 Razorbills were similar to those made in the 1994/5 baseline study, and would likely qualify the Bay as nationally important for both species (2) The regular occurrence of moderate numbers of foraging European Storm-petrels in offshore waters during the summer/early autumn months, in higher numbers than the 1994/5 baseline (3) The regular occurrence of moderate numbers of scavenging Great Skuas in offshore waters during the summer/early autumn months, in higher numbers than 1994/5. (4) The winter presence of small numbers of Great Skua in offshore areas, representing a westerly range extension to that previously documented. Thirty-eight sightings of three other cetacean species were recorded on effort-related surveys including 19 sightings of Harbour Porpoise, plus single sightings of Bottlenose Dolphin and Common Dolphin on Natural England surveys. Amongst the sightings, of particular significance was (1) the regular presence of Harbour Porpoise in all seasons in offshore waters and (2) a large pod of Bottlenose Dolphins in the middle of Lyme Bay during February 7

8 2009 comprising a high proportion of mother/calf pairs, suggesting the areas is used as a nursery ground. The inshore sightings of Bottlenose Dolphin and offshore sightings of Harbour Porpoise concur with the results found during the 1994/5 baseline study. Fifty casual sightings of six cetacean species were collated, chiefly from skippers of local dive, angling and fishing boats following postcard distribution and personal contact. Thirty-seven of the casual sightings were obtained during a three month period through the Natural England highlighting the potential to encourage data flow and interest amongst local skippers with modest resource investments. Very few of these sightings were being captured elsewhere demonstrating that the work complements rather than duplicates existing sightings schemes. Conclusions from the round of discussions with fishermen, representatives from fisheries organisations and recreational dive boat owners, included: (1) It is considered that there is currently very limited potential for fishermen involved in scallop dredging to diversify into ecotourism and take the public out on marine wildlife trips due to high running costs. (2) A need for less technical language when engaging the fishing community with conservation plans and issues was identified (3) There is considerable potential to develop the skills and interests in marine wildlife of local skippers through further engagement activities. Although sound progress has been made in developing an evidence base on the offshore status of Balearic Shearwater and White-beaked Dolphin in Lyme Bay, a number of the conclusions are tentative because sightings rates and photographic captures are low and survey coverage has been uneven. A number of recommendations are made on how the work could be developed including : (1) Repeat Natural England funded transect surveys to enable modelling of habitat preferences/predicted distribution and estimation of absolute abundance from photographic captures (2) Targeted surveys to improve sample sizes of photographic captures of White-beaked Dolphin and to identify core foraging, roosting and moulting areas for Balearic Shearwater (Portland Bill area) and White-beaked Dolphin (3) Investigation of Balearic Shearwater behaviour and ecology through satellite telemetry (4) Acoustic monitoring (deployment of static hydrophones) of White-beaked Dolphins and other cetaceans in central Lyme Bay (5) Developing a Lyme Bay Wildlife Officer post to continue the stakeholder engagement work (6) Extending White-beaked Dolphin work beyond southwest England. 8

9 1.0 Introduction There are numerous localities along the shallow coastline of Lyme Bay where land-based seawatching for seabirds and cetaceans is regularly undertaken. Recording at selected hotspots such as Berry Head and Portland Bill has detected the regular seasonal presence of conservation priority species including Balearic Shearwater, Bottlenose Dolphin and Harbour Porpoise. In contrast, little offshore scientific recording has been carried out. The only systematic surveys were completed in 1994/1995, when Ambios Consultants intensively sampled inner Lyme Bay for seabirds and cetaceans as part of an environmental study commissioned by Kerr McGee Oil (UK) and in 2005, when a single trackline was sampled as part of the SCANS 2 (Small Cetacean Abundance in the North Sea) survey. Information on the current status of seabirds and cetaceans in the offshore waters (defined as more than 2km from land) of Lyme Bay is generally poorly known and the middle of the Bay has never been intensively sampled in a systematic way. In 2006, the conservation and research charity Marinelife, in collaboration with the RSPB and SeaWatch SW, established a programme of cetacean and seabird surveys in the offshore waters of Lyme Bay, focussed on Balearic Shearwater. The impetus for the surveys was the suggestion that Lyme Bay may be an internationally important moulting ground for this highly threatened seabird (Helen Booker, RSPB pers. comm.). The main purpose of the surveys was to identify offshore status, behaviour (including fishery interactions) and habitat preferences, with a view to identifying core areas of distribution that may inform selection of candidate Marine Special Protection Areas (SPAs) for the species. Surveys were undertaken by recruiting volunteers to carry out effort-related recording from dive, angling and fishing boats, where passage was sponsored by the skippers. To fill coverage gaps and seek for sought after species, a smaller number of charter trips were also made. In addition to Balearic Shearwaters, the surveys detected a wide diversity of cetaceans and seabirds in Lyme Bay. Of particular significance were regular sightings of White-beaked Dolphin in a relatively restricted area. A number of the animals were photographed and had unique markings, highlighting the potential to develop a photo-identification catalogue. Most of the survey effort and collation of casual records was carried out during the summer months, with the winter status of both species remaining particularly poorly known. A programme of community engagement was established to encourage and collate casual records from local skippers and recorders. The work demonstrated that there was considerable interest in marine wildlife amongst many of the skippers, with high potential to develop skills and knowledge further. In contrast relations between a number of conservation bodies including Natural England and sectors of the shell (scallop) fishing community have recently been strained, due to a ban on scallop dredging and bottom trawling across 60 square miles of Lyme Bay imposed in There is a need to explore ways of improving relations with the fishing community and to identify opportunities (e.g. ecotourism) for fishermen impacted by the ban. In 2009, a new project was formulated in partnership with Natural England to address some of the knowledge gaps and to synthesise information on Balearic Shearwater, White-beaked Dolphin and other marine animals to inform future conservation strategies and to continue to develop the programme of public and local skipper engagement. 9

10 1.1 Objectives The specific objectives of the project were: 1. To carry out a systematic winter survey of central Lyme Bay covering the core area where White-beaked Dolphins were recorded from using distance sampling techniques. 2. To describe the status and evaluate the importance of Lyme Bay for Balearic Shearwater and White-beaked Dolphin. 3. To develop and make available via the internet Marinelife s photo-identification catalogue of White-beaked Dolphins and other cetaceans taken in Lyme Bay. 4. To maintain and develop public and local skipper engagement in Lyme Bay marine animals through a sightings scheme, postcard survey, press release and other public relations activities and to explore opportunities for fishermen impacted by the fishing ban. 5. To suggest future research and engagement work that will support the conservation of marine animals in Lyme Bay. 1.2 Policy relevance to Natural England The work aims to contribute data, knowledge and stakeholder engagement activities relevant to a number of Natural England Corporate Plan Targets including: 1.3.1: A draft plan for all English Marine Protected Areas (MPAs) by 2011, incorporating Special Areas of Conservation (SACs) and Special Protection Areas (SPAs) to provide a coherent network of sites with clear agreed objectives and a monitoring strategy and a programme in place to provide evidence-based advice to competent authorities : Contribution to halting the decline in marine biodiversity by 2010, through leadership of the marine BAP work stream of the England Biodiversity Strategy : To provide data for a robust evidence base to underpin a compelling vision of future landscapes adapting to climate change and contributing to climate change mitigation. A1.2: The development of strong relationships with stakeholders, for the benefit of the natural environment. Advocacy (improved liaison with impacted fishermen). 2.0 Study area 2.1 Habitat and fisheries Lyme Bay is the largest bay in Britain covering approximately 2460 km 2 and is located off the east Devon and west Dorset coastlines of south west of England. It spans from Start Point (3 38'21W, 50 13'16N) in the west to Portland Bill (2 27'12W, 50 30'49N) in the east, a distance of 90 kilometres. Within the Bay, water depths increase gradually offshore, to a maximum depth of around 60 metres at the 12 mile limit. However, around Start Point the seabed drops away steeply, and 60 metre depths are present within 5 km of the coastline. Current speeds in Lyme Bay are generally low, around 0.5 knots inshore, increasing around headlands such as Start Point and Portland Bill to up to 5 knots at spring tides. Sea surface temperatures in winter range 10

11 between 6º C and 10º C, whilst in summer they are on average between 15 and 17ºC. During the summer months, temperatures increase northwards towards the coast as water depth decreases. Species and seabed habitat diversity is high, because Lyme Bay is an ecotone which straddles the divide between the warm waters of the south west, and the colder waters of the North Sea and eastern Channel. A number of warm water species reach their easterly limit here whilst Lyme Bay is also important area for offshore bedrock reefs which support unusually large and mature populations of a number of slow growing and fragile species, including pink sea fan Eunicella verrucosa, rare red seaweeds and the southern sunset coral Leptopsammia pruvoti. A wide variety of sediments are present (Figure 2.1). Sediments are finest to the west of the Bay with muddy sands between Tor Bay and Exmouth as well as sandy, gravel and cobble substrata. Figure 2.1: Sediments of Lyme Bay and surrounding waters (taken from Poulton et al 2002). A front divides the shallows of Lyme Bay from deeper offshore water, approximately following the 40-metre contour (Figure 2.2). On the landward side of these fronts there is mixed water due to shallow seas and stronger tides, whilst on the deeper and slower flowing open sea side there is stratified water (water temperature cooler in lower layers than the surface). Within frontal zones, primary production is higher than surrounding waters, consequently both the abundance and availability of seabird and cetacean prey is likely to be enhanced. Figure 2.2: The location of fronts and mixing properties of Lyme Bay and surrounding waters (Source Maddock et al. 1981) 11

12 To the east of Portland Bill, there is substantial tidal bank known as the Shambles Bank, formed due to the anti-clockwise circulation of tidal water (an eddy) deflected off the Isle of Portland (Figure 2.3). A smaller bank is also present west of the Bill. The Shambles is an important feeding ground for seabirds. Figure 2.3: The Shambles Bank off Portland Bill. (Source Pingree 1978) Lyme Bay supports a wide range of fishing activity, including beam trawling for demersal fish; (e.g. Sole, Plaice, Turbot, Brill), otter trawling for demersal fish and pelagic fish (e.g. white fish and non-quota species including Cuttlefish, Squid, Red Mullet and Sea Bream); winter pelagic and pair trawling for sprats; Scallop dredging; and potting for Brown and Spider Crabs, Whelks and Lobsters. In coastal and estuary waters a number of small-scale fisheries use a variety of methods including potting, netting (e.g. for Cod, Pollock, Ling, Bass), lining (e.g. for Bass) and seining (e.g. for Salmon, Sea Trout, Bass and Sandeels). Commercial fishing up to the 12 nautical mile limit is managed jointly by the Devon Sea Fisheries Committee for Devon and the Southern Sea Fisheries Committee for Dorset. The most important Lyme Bay fishing ports are Brixham, Teignmouth, Exmouth, Lyme Regis, West Bay and Weymouth, although the Bay is also regularly fished by trawlers from French Channel ports and further afield (e.g. from the Netherlands and Scotland). Figure 2.4: Distribution of main fishing activities in Lyme Bay on sightings from the DSFC patrol vessel (Source: University of Plymouth) There is a growing industry of charter (and casual) angling vessels and Weymouth is home to the largest charter angling fleet in the country. Catch data are not recorded for anglers and 12

13 hobby fishermen, but it is likely that they contribute a considerable proportion of some species landings (e.g. Cod, Conger Eel and Black Bream). Both commercial fishing and recreational sea angling boats present many opportunities for scavenging seabirds. 2.2 Baseline offshore effort-related surveys Kerr-McGee study and SCANS II A baseline assessment of offshore seabird and cetacean status of inner Lyme Bay is available through monthly seabird and cetacean surveys completed from January 1994 to February 1995 by Ambios Consultants for Kerr McGee Oil. Seabirds were surveyed using standardised JNCC Seabirds At Sea Team methods, whilst cetaceans were surveyed using a strip transect method. Three tracklines were established each comprising 6-9 sections at distances of 2-29km from the shore and of 10-20km in length (Figure 5.14). The total transect length was 330km, with a sample area of 1500km 2. Over the 13 month period 4537km were travelled along the tracklines. In the Small Cetacean Abundance in the European Atlantic and North Sea (SCANS) survey in 1994 Lyme Bay was not sampled. In the 2005 SCANS II survey, a single aerial trackline ran east from the west coast of Lyme Bay (between Strete and Slapton) through the middle of Lyme Bay for 90km, ending 18km SSE of Portland Bill. 3.0 Focal species 3.1 Balearic Shearwater Conservation status The Balearic Shearwater Puffinus mauretanicus is the only European seabird to be listed as critically endangered (the highest threat category) on the recently released 2007 International Union for Conservation of Nature and Natural Resources (IUCN) Red List. It is threatened with extinction this century due to low adult survival rates thought to be caused by a combination of predation by introduced mammals, human disturbance and bycatch in longline fisheries. In the Mediterranean there are extensive conservation measures underway to reduce bycatch, eradicate predation and disturbance and to designate protected areas. Understanding the prey items and feeding distribution of Balearic shearwaters is a requirement of the European Action Plan for the species. The Balearic Shearwater is the rarest bird species regularly occurring in the UK. In May 2009, it was added to the Red List of UK Birds of Conservation Concern. JNCC are currently investigating candidate Special Protection Areas (SPA s) for the species Range and population The Balearic Shearwater breeds in the Balearic Islands of Spain in the western Mediterranean. In 2005, there was an estimated 2,000-2,400 breeding pairs at 24 different sites. The world population was thought until recently to number 8,000-10,000 individuals, however recent 13

14 surveys suggest the total population may number 20,000-30,000 birds. Reasons for the discrepancy between breeding and non-breeding population estimates are unclear, but it is most likely that this species has a particularly large floating population of immatures and nonbreeders. The presence of unknown breeding sites is a further possibility. Figure 3.1: Breeding distribution (pink circles) of Balearic Shearwater in the Mediterranean (Source: European Bird Census Council) Life cycle The Balearic Shearwater breeds on cliffs and small islets between February and June. Most birds leave the Mediterranean for a post-breeding moult in the Bay of Biscay, although some remain in the Alboran Sea and increasingly birds are summering off south-west Britain. RSPB calculations in 2001 determined that the average UK population was 1543 birds per year between 1995 and The increase in UK waters is most likely linked to climate change and increases in sea surface temperature (Wynn et al. 2007) although other factors including fisheries-related changes in prey distribution and abundance may also be important (Votier et al., 2008). Birds gradually return to the Mediterranean between September and November. In winter, the species chiefly occurs in the Balearic Sea and off the north-east coast of Spain, though increasingly birds are remaining on their northern moulting grounds Diet Balearic Shearwaters self-forage on small shoaling pelagic fish including Anchovies, Sandeels, Sprats and Sardines. Scavenging on fishery discards from purse seines and demersal trawlers is also important during the breeding season (up to ~40% of foraging efforts), when surface productivity is naturally low in the Mediterranean (Arcos et al. 2002). Balearic Shearwaters also obtain food by capturing fish under floating drifting objects, associating with sub-surface predators, and feeding upon plankton especially during the morning and early evenings. Birds may form concentrations around oceanic fronts where plankton and shoaling fishing are abundant. 14

15 Moulting adult Balearic Shearwater, Dorset (Photo: Tom Brereton) Juvenile Balearic Shearwater, Dorset (Photo: Tom Brereton) Post-breeding distribution is thought to be associated with the distribution of clupeid fish, especially Anchovies. Therefore, the change in distribution of Shearwaters is thought to be associated with changes in prey distribution, either linked to fishing activity or climate change (Yesou, 2003). 15

16 3.2 White-beaked Dolphin Protection measures There is a wealth of European legislation aimed at conserving the species that includes: Appendix II of the BONN Convention, an agreement which requires protection of migratory wild animals across all or part of their natural range through international co-operation (applied to this species from 1983). Appendix II of the BERN Convention on the Conservation of European Wildlife and Natural Habitats (applied to this species from 1987), which requires appropriate and necessary legislative and administrative measures to ensure protection. Any exploitation must also be regulated to keep the populations out of danger. Annex IV of the EU Habitats Directive (1992) for animal and plant species of community interest in need of strict protection. Under Annex IV the keeping, sale or exchange of such species is banned, as well as deliberate capture and killing. There is a requirement to assess the Favourable Conservation Status at a UK scale of each species every six years. Appendix II of CITES (Convention on International Trade in Endangered Species) - Imposes strict regulation on the trade of species that may not necessarily be currently threatened with extinction to prevent overexploitation. UK legislation includes: Schedule 5 of the Wildlife and Countryside Act 1981 (as amended), which gives full protection within British territorial waters. The Act affords protection from killing or injury, sale, destruction of a particular habitat (which they use for protection of shelter) and disturbance. White-beaked Dolphin is also a priority species in the UK Biodiversity Action Plan (UK BAP), being one of six small dolphin species in a grouped plan. Relevant actions in the UK BAP that highlight the need for research, survey and monitoring data on White-beaked and other dolphins include: Ensure that Special Areas for Conservation (SAC) management schemes recognise the need for appropriate measures to protect against habitat modification, disturbance, and contaminant inputs which might affect dolphins. The safeguarding of these sites will require monitoring of potential impacts, and regulation of activities. Give consideration to the feasibility of marine protected areas for dolphins in the context of the proposed DETR working group on marine protected areas. These should include consideration of the importance of the area for calving, as a nursery ground and for feeding. By 2004 establish marine protected areas for small dolphins which take into account the likelihood of human activities that would be harmful to cetaceans living there. Commission autecological studies of all UK dolphin species to identify appropriate habitat management needs. Support research into predicting the effects of climate change on small dolphins. 16

17 White-beaked Dolphin, Lyme Bay (Photo: Gareth Knass) Distribution White-beaked Dolphin has a more limited range than most other cetacean species present in UK waters, being found only in cool temperate and subarctic waters of the north Atlantic (Reid et al. 2003) (Figure 3.2). The population in the eastern Atlantic is thought to be larger than that in the west, with a range extending from northern Norway and Iceland to the British Isles and North Sea. Figure 3.2: White-beaked Dolphin global distribution (Source: adapted from Cawardine, 1995). 17

18 The species is found mostly in continental shelf waters of the northern and central North Sea and west of Britain and Ireland, where water depth is chiefly between 50 m and 100m, and more rarely out to the 200 m depth contour (Northridge et al. 1995; Weir et al. 2001; Reid et al.2003) (Figure 3.3). Figure 3.3: Distribution of White-beaked Dolphin around the British Isles. Status: Regular (dark shading); Occasional (intermediate shading); Casual/Absent (light shading). (Source: Seawatch Foundation). Casual and effort-related sightings data suggests White-beaked Dolphin is a rare species in the Channel in coastal areas. For example, through almost 3000 hours of effort-based observations off Gwennap Head over the July-October period , and where water depths exceed 50m relatively close to the shore, no White-beaked Dolphins have been recorded whilst Common Dolphin, Bottlenose Dolphin and Risso s Dolphin are al regularly seen. However,, there are a relatively high number of strandings from the south-west at levels comparable with the east coast of England where the species occurs regularly offshore (Figure 3.4). These data possibly indicate White-beaked Dolphin is under-recorded in south west waters due to its preference for under sampled offshore waters. Deep water (>200m) may form a geographical barrier to movement and it has been suggested that the population around Britain and Ireland (south of north of 61 o N) is discrete from other populations in the north Atlantic (Northridge et al. 1995). A recent study of the Minch, found White-beaked Dolphin in a restricted area in waters m deep and in temperatures from ºC and 22-32km from the shore (Weir 2007). White-beaked Dolphin is much less common in the southern North Sea, the English Channel (e.g. <20 records for the eastern English Channel) and Irish Sea, though recent year-round ferry surveys between Essex and Holland have detected regular occurrence from March to June (F. Zanderink pers. comm.). There have also been a few sightings in the Bay of Biscay and as far south as the Straits of Gibraltar (Pollock et al. 1997, 2000, Marinelife unpublished data). The few available reports of White-beaked Dolphins stranded on the French side of the English Channel have all been of animals found during the winter months (Collet et al. 1981; Duguy, 1984; 1987; 1988). 18

19 Figure 3.4: Location of White-beaked Dolphin stranded around the UK and Ireland by region (black lines). Figures in brackets represent monthly average sea surface temperatures during winter (January) and summer (august) for the year (Source: Canning 2007). Distribution has been linked to sea surface temperature, local primary productivity, prey abundance and absences of other dolphin species including Common Dolphin (MacLeod et al. 2007; Weir et al. 2007). The most important explanatory variable defining their preferred habitat is water temperature, with their occurrence decreasing substantially in water temperatures greater than o C (MacLeod et al. 2007, 2008). As a result, while Whitebeaked Dolphins are the most dominant neritic (shelf water) dolphin species in UK cooler waters, they become much rarer in water temperatures above ~12-14 o C and are replaced by the Common Dolphin as the dominant neritic dolphin species when this species is present (MacLeod et al. 2007a; 2008). At temperatures above ~18 o C, White-beaked Dolphins seem to be very rare or absent altogether. Due to a close association between water temperature and the distribution of White-beaked Dolphins, the greatest threat to this species in UK waters is considered to be climate change Behaviour and social structure The social structure of White-beaked Dolphin has been little studied, although there appears to be segregation by age and sex, with separate juvenile groups and adult/calf groups forming (Reeves et al. 1999). The age of sexual maturity for the White-beaked Dolphin is not known but females seem to become mature when they grow to 2.4m and males to 2.5m (~80% of their maximum size). Not much is known about reproduction either, but mating is thought to take place predominantly in the summer between June and September, with gestation lasting months, with calving occurring in early summer (Kinze et al., 1997). Although group sizes of up to 1,500 have been reported (especially in the core parts of their range), most reports consist of 10 animals or less (Reid et al., 2003). White-beaked Dolphins are relatively fast powerful swimmers, with average speeds of 6-12kmh and a maximum of up to 30kmh (Reid et al. 2003). They frequently bow-ride vessels 19

20 and are sometimes acrobatic (especially when feeding), breaching on to their sides or backwards. They mix with other cetacean species to feed in some regions (Reeves et al. 1999) Abundance In the SCANS II survey in 2005, abundance was estimated at 10,565 (CV = 0.29) in the North Sea and adjacent waters and 11,700 (CV >0.6) in the west of Scotland (Hammond and Macleod 2006). The highest densities were reported to be in the waters off western Scotland. The British Isles population is considered important and thought to comprise a substantial but unknown proportion of the species worldwide total population. The previous SCANS survey estimated abundance in the North Sea and adjacent waters at 7,856 (CV = 0.30), though the apparent increase since 1994 (by ~3000) is not statistically significant. There is a degree of uncertainty on the population trend as both estimates have large confidence intervals, and there are also concerns with current abundance estimates especially for western Scotland (MacLeod et al. in prep). None were seen in the Channel on either SCANS survey. Figure 3.5: SCANS II abundance estimates for White-beaked Dolphin. (Source: Hammond and MacLeod 2006) Diet White-beaked dolphins eat a variety of prey including fish, squid and some crustaceans. The diet of those found around Britain includes Whiting, Hake, Herring, Cod, Mackerel, Scad, Sand Eel, Long Rough Dab, Trisopterus sp, and the squid Eledone cirrhosa (Evans 1992; Santos et al Canning 2007, Canning et al. 2008). In Scotland, the main species found in the stomachs of stranded animals include Haddock, Whiting, Cod and other white fish (gadoids) (Canning 2007). Most of the Haddock eaten ranged between mm total lengths, while whiting ranged between mm total length (Canning 2007, Canning et al. 2008). In Holland, Whiting appears to be the most common species of fish eaten (Smeenk & Gaemers, 1987; Kinze et a., 1997) while in Germany it is Cod (Lick et al. 1995). The stomach contents of one animal stranded along the Normandy coastline has been examined (Pierrepont 2005) and comprised of two thirds white fish ( Pout Whiting, Pollock, Herring) and one third crustaceans. At sea, anecdotal observations have lead to suggestions that White-beaked Dolphins have been associated with Herring (Evans 1980) and Mackerel shoals (Evans 1987) on the west 20

21 coast of Scotland and that on the east coast inshore sightings coincide with Mackerel appearing in coastal waters Recent distribution shifts The most recent assessment of species conservation status completed as part of Habitats Directive reporting (JNCC 2007) suggest there is no evidence of decline in range during recent years, or historically. The assessment was largely based on SCANS and SCANS II data. However, a substantial body of evidence suggests distribution change is occurring. A recent study reported an apparent decline in the occurrence and relative abundance of Whitebeaked Dolphins in north-west Scotland and a corresponding increase in Common Dolphins correlating with increases in local water temperature (Macleod 2004, MacLeod et al. 2005; MacLeod et al. 2007). A more wide-ranging analysis indicated that there had been a marked decline in the occurrence of White-Beaked Dolphins in 10 of the 21 coarse-scale oceanographic regions of the UK between the 1990s and the 2000s (Macleod et al. in prep). Since the 1990s there has also been a northerly shift in the locations of reported strandings (Jepson 2006) from along the east coast from Norfolk upwards pre-2000, to the Highland region of north east Scotland or the Northern Isles since 2000 (Jepson 2006). A decline has been noted from ferry surveys in the North Sea (Frank Zanderink pers. comm.). These distribution changes are a cause of conservation concern, as it is thought there is very limited potential for this and other cold-water shelf species to track north as sea temperatures rise through climate change, because beyond 60-62ºN the water is too deep (>200m) (MacLeod et al. 2007). This change would elevate the conservation importance of any regular occurrence of White-beaked Dolphins in Lyme Bay. 4.0 Methods 4.1 Opportunistic surveys from Surveys were undertaken by volunteers on commercial dive, angling and fishing trips, with free places provided by local skippers. Volunteer recorders from Devon and Dorset were recruited from Marinelife, the Dorset Bird Club and the RSPB, with additional surveyors coming forward following sightings reports published on various websites, allowing survey coverage to extend into Hampshire and Cornwall. All of the survey effort was co-ordinated by Marinelife. RSPB involvement ceased after The surveys worked by teaming up volunteer recorders with individual boat skippers, so that arrangements could be made between both parties when places became available and weather conditions were suitable for surveys. Trips lasted 6-12 hours, with fishing/diving being carried out at 1-3 localities over the day anchoring for between 30 minutes and 3 hours at a time. The boats travelled at speeds of 8-15 knots. Return routes were occasionally the same as outward routes, especially when trips had been made to wrecks well offshore. To fill coverage gaps and seek sought after species, a smaller number of charter trips were made, utilising the same recording methods but with up to 12 observers present. On each trip, effort-related seabird and cetacean recording was carried out. Sightings data collected for each Balearic Shearwater and cetacean encounter included: age and number of 21

22 individuals, distance (estimated using a Heinemann stick or with laser range finder binoculars) and angle (using graticule binoculars or by angle board) to the sighting, position (using a GPS), and behaviour and weather/sea conditions (including sea state). For Balearic Shearwaters, behaviour at point of first observation was noted and categorised as either: (1) Flying passing through (2) Flying responsive movement towards the boat (3) Natural feeding - including seen in flight circling an area (4) Scavenge feeding around fishing boats (including flying around the boat) and/or (5) Resting on the water. Subsequent behaviour (if different) for the duration of the sighting was also recorded, into one or more of the following categories: (6) Flying passing through (7) Flying responsive movement towards the boat (8) Natural feeding - including seen in flight circling an area (9) Scavenge feeding around fishing boats (including flying around the boat) and/or (10) Resting on the water. For cetaceans, behaviour categories (following Evans, 1995) were (1) Whale blow (2) Slow/normal swim: leisurely surfacing with no splash (3) Feeding: prey seen in vicinity or animal changing direction as if in pursuit (4) Fast swim: rapid surfacing, possibly with white water (5) Leap/splashing: leaping out of the water, tail or fin slapping; (6) Bow-ride: coming to boat and riding bow wave (7) Rest/milling: lying motionless at surface (logging) or slow, synchronous surfacing. Recording of other seabirds was carried out on the majority of trips. Each seabird observed within an assumed strip width 500m either side of ahead was counted once only, with sightings grouped into minute periods. For each seabird sighting the following recordings were made: species name, number seen and age. Notes on behaviour were also made including associations with fishing vessels, cetaceans, and environment effects such as oiling and fishing net entanglement. Effort data was collected simultaneously with sightings data to enable the number of seabird and cetacean sightings to be scaled to recording effort. At 15 to 30 minute intervals, or whenever the ships course changed, a range of variables were measured, including the ship's speed and course, and sea/weather variables such as sea state and visibility (Evans, 1995). Between June 2007 and January 2009 ~40 surveys were completed, with effort data collected on 30 surveys (Figure 4.1, Table 4.1). Table 4.1: Effort-related surveys in Lyme Bay and surrounding waters Month Type Total January 219 Opportunistic 219 February 616 NE surveys 616 March 546 NE surveys 546 April 343 NE surveys 343 May 473 Opportunistic 473 June Opportunistic 548 July Opportunistic 444 August Opportunistic 871 September 373 Opportunistic 373 October 225 Opportunistic 225 November 211 Opportunistic 211 Total

23 These data were entered into a geographic information system (GIS) created in ESRI ARCview 3.3. The latitude and longitude of all bird sightings (from timings) were calculated using a formula in MS Excel. 4.2 Natural England funded surveys A systematic survey of central Lyme Bay where White-beaked Dolphins had recently been recorded was completed between February and April A sampling grid was superimposed over the area of past sightings and a series of 42-km long north-south tracklines each 8-km apart was established. Because White-beaked Dolphins were not seen, the search area was extended to other possible suitable habitats including a spawning ground for two known important prey sources, Cod and Whiting, south of Prawle Point. In total more than 1000km of trackline was sampled on seven dates in areas with post-2006 records of Whitebeaked Dolphin. On each survey, effort related line transect (distance sampling) was carried out, as described in the previous section. Additionally, when a dolphin group was encountered sampling was suspended and the group followed ( off transect ) in an attempt to photograph each animal present for photo-identification purposes. Once this had been done, the boat returned to the track line to complete the days sampling. Photo-identification was carried out using a range of Nikon and Canon digital SLR camera equipment. A further modification was that seabird behaviour (other than for Balearics) was categorised as either Flying or Sat on the Sea. Two additional effort-related surveys were conducted to search for winter presence of Balearic Shearwaters in Lyme Bay, the first trip targeted around Portland Bill and the second inshore waters between Berry Head and Exmouth. The latter survey also covered part of the core area for White-beaked Dolphin. Total survey effort on Natural England surveys is shown in Figure 4.1 and Table 4.1. Figure 4.1: Effort-related surveys in Lyme Bay (red = NE funded surveys in 2009, green = other) 23

24 4.3 Land-based counts of Balearic Shearwater All land-based counts of Balearic Shearwater for Lyme Bay and the rest of the UK were collated through the SeaWatch SW project, managed by Russell Wynn of the National Oceanography Centre, Southampton. Coverage from land is considered good as there are a number of sites where seawatching effort is high including Berry Head, Chesil Beach, Dawlish Warren, Hope s Nose, Portland Bill, Prawle Point, Seaton, West Bay and West Bexington. 4.4 Overlaying sightings with environmental data Data on water depth were extracted from the Seazone Hydrospatial British Geological Society Digibath 250m resolution data set supplied by NE. A digital map of sediment classes in the survey area was obtained from the British Geological Survey. All data were imported into a GIS, ArcView 3.2 (ESRI 1999) to form the basic environmental coverage on which analyses with at-sea sightings data were based. Sightings-specific weekly and where available daily sea surface temperature (SST) composites for Lyme Bay at 1-km square resolution were obtained from NERC Earth Observation Data Acquisition and Analysis Service (NEODDA) managed by NERC & Plymouth Marine Laboratory es/pa/weekly_all/sst/ Mean distance from shore of sightings were calculated using Memory Map Ordnance Survey 2004 software. 4.5 Stakeholder engagement Casual records of Balearic Shearwater, White-beaked Dolphin and other cetaceans were collected from skippers, wildlife recorders and recording organisations including the Devon Wildlife Trust. In an effort to increase the number of records submitted by the public, a postcard survey was launched for Lyme Bay dolphins and shearwaters and a website established to enable online submission of data (see below). In particular the postcard survey was specifically targeted at fishermen, recreational dive and angling boats and yachtsmen. Figure 4.2 Dolphin and shearwater postcard surveys 24

25 Figure 4.3 Data entry and reporting functionality of new web pages to capture sightings from local skippers and members of the public Meetings were held with representatives from the recreational angling boat and commercial fishing communities to explore ways of promoting the project and encouraging improved relations with conservation bodies. One important objective was to explore ways in which relations with fishermen and other stakeholders impacted by the scalloping ban could be improved, including whether there was any potential for fishermen to become involved in ecotourism. In addition a VIP boat trip to look for White-beaked Dolphin provided an opportunity for senior Natural England staff to meet with representatives from the fishing community and other stakeholders involved in marine economic activity and research in Lyme Bay. 5.0 Results 5.1 Balearic Shearwater Effort-related observations from sea 63 at-sea sightings of 105 birds were collected from June 2007 to April 2009, including 33 sightings of 63 birds on effort related surveys (Figure 5.1, Table 5.1). 74% of sightings were of singletons, including a bird in flight on Natural England surveys in February Birds seen at sea in the wider Channel are illustrated in Appendix 1. 25

26 or more Figure 5.1: Balearic shearwaters recorded in Lyme Bay from effort-related and casual surveys. Closed circles are sightings from effort surveys while open circles are casual sightings. The size of the circle indicates the number of birds recorded. Depth contours shown in blue and are 10m, 20m and 50m. Survey effort is shown as red dotted lines. 67% of sightings were categorised as flying birds (n=22), 21% (n=7) were observed scavenging around boats, whilst the remaining 12% were seen sat on the sea. Of the seven scavenging sightings, four were around angling boats, two around beam trawlers whilst one bird was noted around a pelagic trawler. Balearic Shearwaters scavenged amongst a range of other seabirds including Razorbills, large gull species, Great Skuas and Fulmars. As in previous years, birds seen in association with fishing boats were tame at times and swam within a few metres of boats. Whilst scavenging, there was no evidence to indicate that Balearic Shearwaters were being unduly harassed by large gull species or other seabirds. In addition to scavenging behaviour, birds were also seen diving for fish around these boats, though encounters did not identify which prey species the birds were feeding on. Balearic Shearwaters did not linger as long as other seabirds (e.g. Herring Gull, Kittiwake and Fulmar) around fishing boats if discard was not readily available. In both 2007 and 2008 the main concentrations of birds found were around Portland Bill. The birds were chiefly seen either (1) scavenging around angling and fishing boats, (2) flying past Portland Bill (up to 10 in a single flock) or (3) sat on the sea in small flocks (up to eight) up to 11.5km to the south-west (Figure 5.1). 26

27 Table 5.1: Monthly summary of Balearic Shearwater sightings Month No. per 100 Km on effort surveys No. sightings No. counted Flock size range January February March April May June July August September October November December n/a n/a n/a n/a Total Survey effort has not been even across Lyme Bay, so the results need to be treated with caution. For example, in 2008 land-based records were more numerous in the western Bay and it is possible that coastal aggregations (e.g. in Tor Bay, Berry Head and off Exmouth) may have been missed in this area due to under-sampling. Away from Portland Bill birds were only seen in one s and two s, either in flight or scavenging around angling/fishing boats. Only a single Balearic Shearwater was seen on Kerr-McGee surveys in 1994/1995 providing further evidence to indicate that this species has increased in the region over the last 15 years Land-based counts Balearic Shearwaters in Lyme Bay prior to 2007 A study by Wynn et al. (2007) collated all archive data for Balearic Shearwater from UK and Irish waters. Prior to 1980, the main area in Lyme Bay where the species was recorded was Portland Bill. Records stretching back to the 1950s indicated that average annual totals of birds seen at this site were less than 150. However, short-term influxes occurred between 1958 and 1961 and between 1977 and Several hundred birds per year were recorded during these two periods, with day totals of up to 620 birds peaking in late summer and early autumn. Many of these records referred to birds foraging offshore or undertaking small-scale foraging movements, both off Portland Bill and in Chesil Cove. These two influxes were likely driven by 1) short-term disruptions in prey availability in areas further south, e.g. the French Biscay coast, where a large proportion of the World population traditionally gather to moult between July and October, and/or 2) increased prey concentrations in eastern Lyme Bay. Since 1980, numbers of Balearic Shearwaters recorded annually in Lyme Bay have been about 30-40% of the UK and Irish total (this proportion has remained reasonably constant up to the present day). Annual totals remained at a relatively low level through the 1980s, but started to dramatically increase from the mid-1990s onwards. Numbers have remained elevated since then, albeit with marked inter-annual variability (Wynn et al., 2007; Wynn et al., 2009). The total number of birds reported off Portland Bill exceeded 300 in three years between 1998 and 2006, and approached 750 in The majority are seen between July and 27

28 October, e.g. 85 on 29 July 1998, up to 90 lingering offshore in July 2001, and 77 on 12 Sept Balearic Shearwaters in Lyme Bay in During 2007 a total of 193 records were received for the Lyme Bay area (Figure 5.3). The majority of records came from Portland Bill (91), Prawle Point (21) and Berry Head (20). These three sites alone contributed 132 records (or 68% of the total). The only other site with more than ten records was Seaton. The largest day totals (50+ birds) are listed below: 117 off Portland Bill on 8 July. 90+ off Portland Bill on 5 July. 88 off Portland Bill on 9 July. 74 off Portland Bill on 20 July. 52 off Portland Bill on 22 June. 50 off Portland Bill on 25 June. A further 40 records of birds were received. During 2008 a total of 313 records were received for the Lyme Bay area (Figure 5.4). The majority of records came from Portland Bill (130), Berry Head (53) and Dawlish Warren (49). These three sites alone contributed 232 records (or 74% of the total). Other sites with more than ten records included Prawle Point and Seaton. The largest day totals (50+ birds) are listed below: 109 off Berry Head on 16 Aug. 83 off Berry Head on 18 Aug. 66 off Portland Bill on 1 Sept. 60 off Portland Bill on 4 July. 50 off Portland Bill on 13 Jan. A further 63 records of birds were received. The temporal distribution of records is illustrated in Figure Balearic Shearwater records in Lyme Bay ( ) Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Month Figure 5.2: Temporal distribution of Balearic Shearwater records in Lyme Bay during

29 January 2007 February 2007 March 2007 April 2007 May 2007 June 2007 July 2007 August 2007 September 2007 October 2007 November 2007 December 2007 Figure 5.3: Monthly sightings of Balearic Shearwaters in

30 January 2008 February 2008 March 2008 April 2008 May 2008 June 2008 July 2008 August 2008 September 2008 October 2008 November 2008 December 2008 Figure 5.4: Monthly sightings of Balearic Shearwaters in

31 The above graph shows that the majority of records were received in the period from June to October, although in 2008 over 40 records were also received for January. Not all records specify behaviour, e.g. foraging, roosting or migrating, but analysis of those that do reveals some overall patterns. Off Portland Bill, many of the birds seen during June and July were lingering offshore or undertaking local (post-roost) foraging movements. This was particularly evident in 2007, when up to 117 birds were seen for several weeks, with most showing obvious signs of active wing moult. Up to 2500 Manx Shearwaters were also regularly recorded at this time. The largest counts involved birds moving west early in the morning, indicating that they were roosting somewhere east of Portland Bill. Later in the summer and autumn most birds were seen moving west as part of larger-scale foraging movements. The influx in January 2008 also involved birds foraging offshore or moving west, in association with thousands of Razorbills and other seabirds. Off Seaton most birds are seen moving west, while off Berry Head most birds are moving south (as with other seabirds), although small numbers of birds (up to ten) are occasionally seen feeding offshore or following trawlers as they return to Brixham. Off Dawlish Warren small numbers (typically up to ten birds) are usually seen self-foraging in association with gulls, terns and other seabirds. 5.2 White-beaked Dolphins in Lyme Bay Sightings between 2006 and 2009 Over the period July 2006 to April 2009 twenty sightings of ~300 individual White-beaked Dolphins were recorded in Lyme Bay. Eleven of the sightings were classed as casual records and came from a variety of sources, including two sightings through unidentified dolphins in Lyme Bay videos posted on youtube by yachtsmen. Of the casual records, two of the sightings did not have an exact date and one of these was lacking a precise position. Nine sightings were recorded on effort-related surveys (Figure 5.5). On effort-related surveys White-beaked Dolphins were the second most frequently seen species (after Harbour Porpoise) accounting for approximately a fifth of all cetacean sightings. There were no sightings during effort-related Natural England surveys in the late winter/early spring period of 2009 and it was thought that the animals were not regularly in Lyme Bay over that period. Table 5.2: Monthly summary of White-beaked Dolphin sightings Month No. per 100 Km on effort surveys No. Sightings No. Counted Group size range January February March April May June July August September October November December n/a n/a n/a n/a Total

32 White-beaked Dolphin sightings were recorded in all months except December (no survey effort in this month) and February (presumed absent February 2009) (Table 5.2). The majority of casual records were seen from June to August, reflecting the peak season for yachting, whilst effort-related records were more evenly spread through the year. Figure 5.5: White-beaked dolphins recorded in Lyme Bay from effort-related surveys and casual records. Closed circles are sightings from effort surveys while open circles are casual sightings. The size of the circle indicates the number of dolphins recorded. Depth contours shown in blue and are 10m, 20m and 50m. Survey effort is shown as red dotted lines. Background shading indicates main sediment type. 77% of sightings were of 2-5 animals, with the only groups comprising more than 10 individuals being of 15, 20 and ~200. The latter group was seen by Colin Speedie in August All of the animals sighted on effort related surveys were similar in size, though on casual surveys there were two smaller animals thought to be juveniles in a group of three off Lyme Regis in March White-beaked Dolphins preferred the central deeper waters of Lyme Bay, with nearly 90% of records being in waters 45-51m deep. Water temperatures ranged from 8.8 to 17.3ºC, with the model class being 15 ºC and no records in the ºC category (Figure 5.6). 95% of sightings were offshore (>2km), the sole land-based observation being from wellwatched Berry Head in April This sighting represented the first observation for the sites principal seawatcher Mark Darlaston, highlighting the relative rarity of the record. Two of the three near shore sightings were in the spring. For effort-elated sightings, the preference for offshore waters was even more apparent with sightings being in the range 16-36km (mean 29km) from land. 32

33 % of all sightings Sea Surface Temperature Category (ºC) Figure 5.6: Water temperatures in 1-km squares where White-beaked Dolphins were recorded Most of the White-beaked dolphin sightings were over predominantly sandy sediments rather than other sediment types (Figure 5.5). In deeper central waters of Lyme Bay, a front (that runs from Portland Bill to Start Point) forms during the summer months (Figure 2.2. Anecdotal records from local angling skippers indicate this area of Lyme Bay supports shoals of Whiting during July and August and has been good for Cod around wrecks over the last four years (Ian Cornwell and Chris Caines pers. comm.) aided by strict quotas Co-occurrence with other cetacean species Harbour Porpoises were regularly recorded in the central areas of Lyme Bay in the same months as White-beaked Dolphin. Few other species were seen when White-beaked Dolphins were around, although there were two records of Common Dolphin, both during the winter months when sea surface temperatures were cold (Figure 5.7). Figure 5.7: Cetacean sightings in months when white-beaked dolphins were recorded in Lyme Bay Depth contours shown in blue and are 10m, 20m and 50m. Survey effort is shown as red dotted lines. Sightings on survey effort are shown as squares. Casual sightings are shown as circles. White: Bottlenose dolphin; Yellow: Common dolphin; Red: Harbour porpoise; Green: Pilot whale; Blue: White-beaked dolphin. 33

34 In months when White-beaked Dolphins were absent, Harbour Porpoise, Common Dolphin and Bottlenose Dolphin were recorded on a number of occasions in the central areas of Lyme Bay (Figure 5.8). These results suggest that there may be competitive interaction and habitat partitioning between Bottlenose Dolphin, Common Dolphin and White-beaked Dolphin (see discussion). In particular the sudden disappearance of White-beaked Dolphin in February 2009 (following regular presence for at least nine months) coincided with the arrival of a large pod of Bottlenose Dolphins. Figure 5.8: Cetacean sightings in months when white-beaked dolphins were not recorded in Lyme Bay Depth contours shown in blue and are 10m, 20m and 50m. Survey effort is shown as red dotted lines. Sightings on survey effort are shown as squares. Casual sightings are shown as circles. White: Bottlenose dolphin; Yellow: Common dolphin; Red: Harbour porpoise; Brown: Minke whale Association with seabirds There were no instances of foraging seabirds (e.g. Gannets, gulls) associating with schools of White-beaked Dolphin, indicating that the species does not principally feed on shoals of fish swimming near the surface. The presumed main prey items, white fish and shellfish, are thought mainly to occur in the lower half of the water column (i.e. >25m deep), which are not targeted by plunge diving/surface feeding seabirds Other recent records of White-beaked Dolphin in the Channel Seven animals were seen off Dungeness Kent in December 2004 (the first record for reserve warden David Walker who has been seawatching daily at the site since 1989). Seven sightings were made in coastal areas off the Cornish coast between 1990 and The records spanned from Gwennap Head in the west to Looe in the east and were all made in July and August (Goodwin et al. 2007). Recent records supplied to Seaquest included 8-10 individuals in the middle of Lyme Bay (DWT) in August 2004, and 20 in Fal Bay, Cornwall and 2 off Nare Head, Cornwall both on the 29 th September On the French side, there were just five sightings up to 2002, although there were reports of regular sightings by fishermen in northern France, especially during the winter months (Kiszka et al. 2004). Three were seen off Cap Gris-Nez, Nord pas de Calais in October 2008 (Source: ( The sole report off the Normandy coastline (where there 34

35 are hundreds of sightings of other species) relates to a group of ~100 off Jersey in January 1985 (François Gally, Groupe d Etude des Cétacés du Cotentin pers. comm.) No White-beaked Dolphins were seen on the four effort related systematic surveys that have been carried out in the Channel in recent years - Scans (1994), Scans II (2005), Kerr-McGee Oil (1994) or JNCC SAS surveys (1994, see White et al. 1995). Figure 5.9: Casual sightings of White-beaked Dolphin post 1985 (excluding Lyme Bay records post-2005) Photo-Identification catalogue A catalogue of uniquely marked White-beaked Dolphins (n=6) and Bottlenose Dolphins (n=24) photographed in Lyme Bay and surrounding waters was established under the project. The catalogue can be downloaded from A project is currently being established with co-workers in the Netherlands and Northumberland to expand the White-beaked Dolphin catalogue into the North Sea the nearest known region where the species regularly occurs off eastern Britain. A uniquely marked White-beaked Dolphin - note the horizontal scratches on the leading edge of the dorsal fin (Photo: James Phillips). 35

36 A photo-identification catalogue of Bottlenose Dolphins from Normandy has recently been compiled, comprising in excess of 200 individual animals. Rather surprisingly, preliminary inspection of the catalogue of Bottlenose Dolphins supplied by Marinelife has not yielded any recaptures, although further analysis work is required (Francoise Gally, GECC pres. comm.). 5.3 Other seabirds recorded in Lyme Bay Over the ~50 effort-related surveys between 2007 and 2009 there were 4250 seabird sightings totalling 43,200 birds of 33 species. 15,530 birds of 30 species were recorded on the nine Natural England surveys from February to April 2009 (Table 5.3). Table 5.3: Seabird sightings in Lyme Bay seen on Natural England surveys from February to April 2009 Cetaceans 14/2 19/2 24/2 28/2 15/3 21/3 29/3 21/4 21/4 Total Red-throated Diver Great Northern Diver Black-throated Diver 1 1 Great Crested Grebe Fulmar Balearic Shearwater 1 1 Great Shearwater 1 1 Manx Shearwater Gannet Cormorant Shag Brent Goose Shelduck 1 1 Common Scoter Great Skua Pomarine Skua 1 1 Herring Gull Lesser Black-backed Gull Great Black-backed Gull Kittiwake Large Gull spp Black Headed Gull Common Gull Mediterranean Gull Sandwich Tern Common Tern 7 7 Commic Tern 6 6 Guillemot - sea Guillemot - land Razorbill Puffin Auk sp * = off transect, but seen nearby by local skippers/other observers Seabird highlights from the surveys included: The regular occurrence of moderate numbers (maximum day count 76) of foraging European Storm-petrels in offshore waters (>3km out) during the summer/early autumn months, especially in central and eastern areas of the Bay (Figure 5.10). This represents a new finding, as Lyme Bay has not been sampled for European Storm-petrels before by the JNCC Seabirds at Sea Team and few were seen during the Kerr-McGee surveys in 1994/5. 36

37 Figure 5.10: European Storm-petrels recorded in Lyme Bay from effort-related and casual surveys. Closed circles are sightings from effort surveys while open circles are casual sightings. The size of the circle indicates the number of birds recorded. Depth contours shown in blue and are 10m, 20m and 50m. Survey effort is shown as red dotted lines. The regular occurrence of moderate numbers (maximum day count 36) of scavenging Great Skuas in offshore waters (mostly >10kmfrom land) during the summer/early autumn months (Figure 5.11). Far fewer were seen on Kerr-McGee surveys suggesting that this species has increased in Lyme Bay since the mid-1990s. This is supported by coastal sightings data from Hampshire (Wynn 2008). Figure 5.11: Great Skuas recorded in Lyme Bay from effort-related and casual surveys during the summer months Closed circles are sightings from effort surveys while open circles are casual sightings. The size of the circle indicates the number of birds recorded. Depth contours shown in blue and are 10m, 20m and 50m. Survey effort is shown as red dotted lines. 37

38 The winter presence of small numbers (maximum day count 5) of Great Skua in offshore areas (>10km from land) (Figure 5.12). This represents a westerly range extension to that previously documented (Stone et al. 1995). Figure 5.12: Great Skuas recorded in Lyme Bay from Natural England effort-related and casual surveys in the early winter period Closed circles are sightings from effort surveys while open circles are casual sightings. The size of the circle indicates the number of birds recorded. Depth contours shown in blue and are 10m, 20m and 50m. Survey effort is shown as red dotted lines. Large numbers of wintering Guillemots widely distributed across Lyme Bay (Figure 5.13). A crude analysis of the data (mean no./km 2 * area Lyme Bay) suggests an approximate abundance estimate of 16,000 Guillemots in February 2009 in Lyme Bay. Birds were equally abundant in surrounding waters, and the wider population is likely to be considerably larger. The abundance estimate for Lyme Bay indicates that the area may be may be nationally important for Guillemot, as the total would represent ~1% of the UK wintering population, assuming the winter population is of a similar order to the breeding population which has been estimated at 1.3 million birds (Seabird 2000 data). The results concur with the findings of the Kerr-McGee study which estimated a wintering population in February 1994 of ~16,000 Guillemots within the sampled areas of Lyme Bay, suggesting there has been little change in wintering status since Though less abundant than Guillemot (25% fewer), substantial numbers of Razorbills were also recorded during the winter months, especially off Portland Bill. A crude abundance estimate of 4,000 Razorbills was made for Lyme Bay in February 2009, which was also the same as the abundance estimate from the Kerr-McGee study in 1995 and would qualify Lyme Bay as being nationally important (see criteria for Guillemot). 38

39 Figure 5.13: Distribution and relative abundance of Guillemots in Lyme Bay on Natural England surveys during the early winter period in Closed circles are sightings from effort surveys while open circles are casual sightings. The size of the circle indicates the number of birds recorded. Depth contours shown in blue and are 10m, 20m and 50m. Survey effort is shown as red dotted lines. Several rare species were seen, most noteworthy amongst them being a Great Shearwater on Natural England surveys in February This is only the seventh Dorset record and the first during the winter. Furthermore, it may also represent the first occurrence of the species in British waters in February. Further comparisons with data collected for the Kerr-McGee indicates that Kittiwakes have decreased, whilst Sooty Shearwaters have increased. 5.4 Other cetaceans seen recorded in Lyme Bay Effort related sightings 38 sightings of three other cetacean species were recorded on effort-related surveys. The species were Bottlenose Dolphin, Common Dolphin and Harbour Porpoise. On Natural England surveys there were 19 sightings of Harbour Porpoise, plus single sightings of Bottlenose Dolphin and Common Dolphin, whilst on other effort-related surveys there were a further 15 sightings of Harbour Porpoise, plus singles of Bottlenose Dolphin and Common Dolphin (Table 5.4). Amongst the sightings, of particular significance was (1) the regular presence of Harbour Porpoise in all seasons in offshore waters (Figure 5.130) and (2) a large pod Bottlenose Dolphins in the middle of Lyme Bay during February 2009 comprising a high proportion of mother/calf pairs, suggesting the areas is used as a nursery ground. 39

40 Table 5.4: Effort related cetacean sightings in Lyme Bay Bottlenose Dolphin Bottlenose Dolphin Common Dolphin Common Dolphin Harbour Porpoise Harbour Porpoise Month No. Sightings No. Counted No. Sightings No. Counted No. Sightings No. Counted January February March 7 12 April May 6 7 June 1 6 July 3 19 August 3 3 September 1 2 October November Total The presence of inshore sightings of Bottlenose Dolphin and offshore sightings of Harbour Porpoise concur with the results found during the Kerr-McGee study (Leaper et al. 1995) in 1994/5 (Figure 5.15). Figure 5.14: Harbour Porpoise effort-related sightings from Marinelife surveys in Lyme Bay during the summer (Apr-Sep) and winter (Oct-Mar) months Red circles are summer sightings, blue circles are winter sightings. Circle sizes are scaled to the number recorded. Depth contours are shown in solid blue lines and are 10m, 20m and 50m. Summer survey effort is shown as red dotted lines, winter survey effort is shown as blue dotted lines. Background shading indicates main sediment type 40

41 Figure 5.15: Cetacean sightings on monthly Kerr-McGee transects in Left side - Bottlenose Dolphin, Right side Harbour Porpoise (Source: Leaper et al. 1995) Casual sightings casual sightings of six cetacean species were collated, chiefly from skippers of local dive, angling and fishing boats following direct contact. These comprised 24 sightings of Bottlenose Dolphin, 17 of Common Dolphin, 5 of Harbour Porpoise and singles of Risso s Dolphin, Minke Whale and Long-finned Pilot Whale. The most obvious difference between casual and effort data was the low proportion of casual Harbour Porpoise sightings received, indicating this species is overlooked by non-experts with busy jobs at sea. 37 of the casual sightings (Figure 5.16) were obtained during a three month period through the Natural England project (postcards, website etc), highlighting the potential to encourage data flow and interest amongst local skippers with modest resource investments. Very few of these sightings were being captured elsewhere demonstrating that the work complements rather than duplicates existing sightings schemes or more Figure 5.16: Casual sightings of cetaceans in Lyme Bay in 2009 obtained through the Natural England project. The size of the circle indicates the number of cetaceans recorded. Depth contours shown in blue and are 10m, 20m and 50m. White: Bottlenose dolphin; Yellow: Common dolphin; Red: Harbour porpoise; Blue: White-beaked dolphin. 41

42 5.5 Stakeholder engagement Postcard distribution The postcards were distributed to 185 skippers of angling, diving and leisure boat trips across southwest England (42 in Hampshire, 70 in Dorset, 51 in Devon, and 22 in Cornwall). Figure 5.17: Location of ports (yellow crosses) where postcards have been distributed to local skippers The postcards were also distributed to 44 Sailing Clubs across Cornwall and Devon (21 Cornwall and 23 Devon), with more planned for Hampshire and Dorset. Figure 5.18: Location of sailing clubs (yellow crosses) where postcards have been distributed to local skippers. Note: Planned distribution = red crosses Fishermen impacted by the ban on scallop dredging Due to the current sensitivities between scallop dredging fishermen and Natural England/the Devon Wildlife Trust only limited progress was made in liaison work. The advice from a number of stakeholders was to let thing settle down and avoid making contact with scallop dredging fishermen, although some indirect contact was made. 42

43 In spite of this limitation, a number of conclusions can be drawn from the round of discussions with fishermen, representatives from fisheries organisations and recreational dive boat owners, including: It is considered that there is currently very limited potential for scallop fishermen to diversify and take the public out on marine wildlife trips. The combined costs of fuel, crew and insurance would likely to make this prohibitively expensive for paying passengers. Furthermore, these boats were not particularly well designed for carrying passengers e.g. often no toilet facilities on board. The market is likely to be too small to enable a complete business change from fishing to ecotourism. Anecdotal feedback from several fishermen contacted (admittedly not scallopers) thought there was no need to find alternative sources of income, as local scallopers had found new and productive fishing grounds away from the exclusion zones. There was a concern in this respect, that the ban may be counter-productive forcing scallopers to move into even more sensitive marine areas, including pristine areas never dredged before. There is a need for less technical language when engaging the fishing community with conservation plans and issues. This is likely to lead to improved understanding and better relations in the long-term. Interest in marine wildlife amongst local skippers is high, and there is considerable potential to develop this interest further through engagement activities. There are likely to be benefits in doing this work, as (1) it is likely to develop a greater interest and understanding for marine wildlife in conservation amongst skippers in the longterm and (2) to provide feedback to conservation bodies on current issues concerning local skippers. 6.0 Discussion 6.1 Importance of Lyme Bay for Balearic Shearwater The analysis of land-based sightings collected through SeaWatch SW indicates that internationally important numbers of Balearic Shearwaters are currently visiting Lyme Bay, and the area in recent years has held about a third of the annual UK and Irish total. The total known breeding population is about pairs (restricted to the Balearic Islands in the Mediterranean Sea), but counts outside the breeding season suggest a total population in excess of 20,000 individuals. Three-figure counts of Balearic Shearwaters have regularly been made in Lyme Bay in recent years, indicating that up to 0.5% of the World population may be present in this small area at any one time. There are also indications that numbers utilising Lyme Bay, and southwest UK in general, are increasing (Wynn and Yesou, 2007; Wynn et al., 2007; Wynn et al., 2009), probably in response to climate and fisheries-driven changes in prey availability (typically small shoaling fish, e.g. Anchovy, Sprat, Sardine). Portland Bill is (historically and presently) an important foraging area for this species, both during the mid-summer moulting period (as in June-July 2007) and in mid-winter (as in January 2008). Offshore surveys have confirmed the relatively high importance of Portland Bill relative to other sampled areas, although parts of Lyme Bay are under-recorded. 43

44 The number of birds utilising Lyme Bay show marked inter-annual variability, probably in response to local changes in prey distribution from local through to regional scales. For example, very few birds were seen in January 2007, and the mid-summer moulting aggregation was 50% smaller in 2008 than Dawlish Warren also appeared to be a favoured foraging area in both late summer and autumn 2007 and 2008, although numbers of birds seen here are typically only in single figures. It should be noted that this analysis is based upon casual sightings data, not effort-based data. There may be other sites within Lyme Bay that receive limited observer coverage but are still important foraging areas for Balearic Shearwaters. Small boat surveys in recent years have indicated that few birds are present away from the coastal zone, but more comprehensive coverage of near shore sites may reveal previously unknown foraging areas. Large-scale foraging movements probably encompass the entire western English Channel, and are most commonly observed between July and October. During such movements, most birds are seen moving west off Portland Bill and through Lyme Bay, before turning south as they reach the western bay off Berry Head and exiting to the west off Prawle Point. It should also be noted that high counts from land-based seawatching sites at times are associated with fresh to strong south/south-west winds and are often followed by far lower counts in subsequent more settled conditions. Given that relative few have been seen at sea in Lyme Bay despite a fair amount of survey effort, these data may indicate that many of the birds seen are wind-driven/assisted from more substantial numbers regularly present in coastal waters of northern France. At Gatteville Normandy, located at the north-east corner of the Cherbourg Peninsula and Cap de la Hague, in the north-west corner, large Balearic Shearwater counts coincide with moderate to strong south west winds (e.g. 482 at Gatteville 7/9/2008, wind SW 5 and 109 at Cap de la Hague 3/9/2006 wind SW4), which support the theory that birds are being displaced (or undertaking wind-assisted foraging flights) north/north-east from the Normandy and Brittany coastlines. Thus high day counts from land can give a false impression of how many birds are regularly utilising Lyme Bay to moult and feed over the summer months Potential threats to the species in UK waters include oil spills, recreational disturbance, offshore windfarms and fisheries bycatch. Although none of these threats has significantly impacted birds using Lyme Bay to date, the oil spill associated with the MSC Napoli grounding in Jan 2007 would almost certainly have affected Balearic Shearwaters if it had occurred a few months later. 6.2 Possible reasons why the Portland Bill area is important for Balearic Shearwaters The sea area to the south-west of Portland Bill is characterised by a tidal front, where food sources including shoaling fish and plankton are likely to be aggregated. The main offshore features in close proximity to Portland Bill are Portland Race and the Shambles Bank. Portland Race is an area of rough water formed by the combined effects of a westerly tidal flow forcing deep water to spill over a shallow reef and a southerly tidal flow diverted by the Isle of Portland. Where the two meet a confused sea state is created. The area is good for Bass fishing and attracts a number of angling boats which use Sandeels and Mackerel as bait, providing opportunities for scavenging by Balearic Shearwaters. The Shambles Bank east of Portland Bill supports large shoals of Sandeels in the summer months and is heavily fished by commercial and private angling boats, providing good opportunities for self-foraging and scavenging by Balearic Shearwaters. Additionally, in recent years, anecdotal evidence from 44

45 anglers is that large shoals of Anchovies, a known vitally important food source for Balearic Shearwaters, have been present in the vicinity of Portland Bill. The presence of shoals of Anchovies may possibly be key in explaining presence and inter-annual variability though precise information on the local occurrence of this prey species is difficult to obtain, as they currently have a higher economic value than similar-sized fish which also occur, hence information is commercially sensitive. The highest numbers of Balearics recorded in the Portland Bill area over the study period were in early July A feature of this period was that the seas were heavily stirred up, evidenced by high Total Suspended Matter concentrations (a turbidity measure) (Figure 6.12) that in themselves have been linked to enhanced biological productivity (Sverdrup et al., 1942; Emery et al., 1973). This combined with warm water temperatures ( C) is likely to have provided suitable conditions for pelagic shoaling fish. The turbid waters may have also made prey items easier to catch. Plunge divers need to be able to see their prey below the surface, whereas pursuit divers such as the Balearic Shearwater may benefit from increased turbidity, which prevents the prey from seeing them coming (Baduini et al. 2003). Figure 6.1: Elevated Total Suspended Matter concentrations (a turbidity measure) concentrations off Portland Bill in early July (Source: Plymouth Marine Lab) 6.3 Importance of Lyme Bay for White-beaked Dolphin The results from Marinelife surveys and collation of casual records over a longer period and a wider area confirm that since at least 2005 and stop press again in summer 2009 Whitebeaked Dolphins have regularly visited Lyme Bay at all times of the year, but especially during the summer months. Canning (2007) found White-beaked Dolphin to be primarily a summer visitor to the deeper waters off Aberdeen, north-east Scotland with occurrence coinciding with calving and groups containing calves. Lyme Bay is the most southerly known site in Europe where White-beaked Dolphins regularly occur. In Lyme Bay up to 200 animals have been seen on a single occasion, which represents ~1% of the total population estimated for north-west European shelf waters, confirming regional and possibly national importance. The available data suggest that Lyme Bay may be the most important locality in the English Channel for White-beaked Dolphin, though this cannot be confirmed due to under-sampling of other areas of the Channel. 45