CETACEAN STRANDINGS INVESTIGATION: ENGLAND AND WALES AND POSEIDON DATABASE

Final Report on Contract CR0177

Conducted for the Department of the Environment, Transport and the Regions

by the

Institute of Zoology The Zoological Society of London Regent’s Park London NW1 4RY England

Report compiled by: Peter M. Bennett, PhD Paul Jepson, MRCVS Rob Deaville, BSc

Contract start date: 12 June 1995 Contract end date: 31 March 2000 CONTENTS

Executive summary …………………………………………………………………. 4

1. Introduction …………………………………………………………………… 6 1.1 Aim 1.2 Policy background 1.3 Achievement of project objectives

2 Methodology …………………………………………………………………… 9 2.1 Management and personnel 2.2 Protocols for reporting of strandings and post-mortem investigation Reporting of marine mammal strandings Reporting of live cetacean strandings Pathology laboratories Standard protocols for post-mortem examination, tissue sampling and data recording 2.3 Collaboration with other organisations 2.4 Tissue archive and Poseidon central database 2.5 Reporting of data 2.6 Training

3 Results …………………………………………………………………………. 17 3.1 Causes of mortality in cetaceans (1995-1999) Entanglement in fishing gear (by-catch) Physical trauma Infectious disease Starvation Live stranding Dystocia and stillborn Neoplasia Other causes of death 3.2 Causes of mortality in grey seals

4 Results of analyses of pooled data …………………………………………….. 23 4.1 Patterns of harbour porpoise mortality (1990-1999) 4.2 Studies of the pathology and epidemiology of cetacean diseases Investigations into the epidemiology of morbillivirus in cetaceans in UK waters The pulmonary pathology of harbour porpoises (1990-1996) 4.3 Relationships between contaminants and infectious disease in harbour porpoises Polychlorinated biphenyls and infectious disease mortality Heavy metals and infectious disease mortality 4.4 Other analyses of contaminants Metals and organochlorines in other species Butyltins Radionuclides 4.5 Other ongoing research of pooled data on harbour porpoises Molecular genetic analysis of population structure Relationships between lungworm abundance and immunosuppressive contaminants Possible combined effect of organochlorines and heavy metals on health status Reproductive system pathology

5 Conclusions…………………………………………………………………….. 31

6 Recommendations for future research ………………………………………. 33

7 List of publications directly resulting from this project 1995-2000…………. 34

Appendices…………………………………………………………………………… 37

1 Details of postmortem examinations conducted during the period of this report 2 The standardised post-mortem examination guidelines and report forms for cetaceans 3 The standardised post-mortem examination guidelines and report forms for seals

List of plates………………………………………………………………………….. 77 Executive summary

During the period of this contract, 359 postmortem examinations of marine mammals stranded or by-caught in commercial fisheries in England and Wales were conducted, comprising 326 cetaceans of 14 different species and 33 grey seals Halichoerus grypus. The most frequently examined cetacean species were the harbour porpoise Phocoena phocoena (215 carcases), common dolphin Delphinus delphis (75) and striped dolphin Stenella coeruleoalba (15) respectively. A cause of mortality was established in 264 of the 326 cetaceans examined (81%). Entanglement in fishing gear (by-catch) was the most frequent cause of mortality in cetacean species representing 45% of all cases where the cause of mortality could be established. This comprised 64 stranded harbour porpoises, 32 common dolphins, one striped dolphin, one white beaked dolphin Lagenorhynchus albirostris and one pilot whale Globicephala melas. In addition, 21 by-caught harbour porpoises were retrieved for postmortem examination from commercial fishing vessels. Many of these known by-catches were reported through the EU-funded BYCARE research programme.

Infectious diseases were frequent causes of mortality in harbour porpoises, accounting for the death of 26 harbour porpoises during the period of this report. The most common causes of infectious disease mortality in harbour porpoises were pneumonias (parasitic and bacterial) and generalised bacterial infections. In collaboration with CEFAS (Burnham Laboratory), we found that contamination by toxic pollutants may be implicated in these cases. Statistical analyses showed that tissue concentrations of PCBs and mercury were significantly higher in porpoises that died of infectious disease compared to healthy porpoises that were accidentally trapped in fishing nets. These results are in the direction predicted by the hypothesis that these industrial pollutants impair immune function in marine top predators. These associations demonstrate the importance of continued monitoring for the possible effects of exposure to persistent environmental contaminants on the health status of marine mammals in UK waters, both in the context of their population viability and also as potential biomarkers of contaminant-related damage to marine ecosystems. Infectious disease mortality was rarely recorded in strandings of other cetacean species.

Since 1995, nine stranded harbour porpoises (8 juveniles, 1 adult) had fatal traumatic lesions that were consistent with those first described in stranded harbour porpoises from the Moray Firth, Scotland and which have been attributed to lethal attack by bottlenose dolphins Tursiops truncatus. All nine of these harbour porpoises stranded within Cardigan Bay, West Wales. Harbour porpoises have a sympatric distribution with a resident population of bottlenose dolphins within Cardigan Bay. These findings represent the first evidence for this intriguing behaviour in bottlenose dolphins outside Scottish waters.

During the period of this contract no mass mortalities of cetaceans or seals were reported from England and Wales. In addition, no cases of morbillivirus were diagnosed in any species during the period of this report. The results of the serological investigation for morbillivirus-specific antibodies provided an interesting insight into the prevalence and epidemiology of morbillivirus in cetaceans in UK waters. There was a very low prevalence of seropositives in harbour porpoises and common dolphins suggesting that morbillivirus is not endemic in these species within UK waters. Apart from one seropositive juvenile pilot whale, all seropositive cetaceans were adults in which morbillivirus- specific antibodies could be the consequence of an infection contracted during 1988-1990 when the last cases of fatal morbillivirus infection were diagnosed in cetaceans in the NE Atlantic. There has been a low prevalence of neoplasia recorded in cetaceans both during the period of this report and since the beginning of strandings research in 1990. Neoplasia is an important biomarker for the potential effects of exposure to carcinogenic environmental compounds such as radionuclides and some polycyclic aromatic hydrocarbons such as benzo-a-pyrene.

It is well known that investigating threats to rare species is difficult and this is especially true with sparsely distributed free-living cetaceans. Our approach to this problem has been to use systematic post-mortem investigations to establish the cause of death and disease status of animals that have stranded on the coastline. This method has obvious limitations, the most important being that it is impossible to be sure that our observations accurately measure the true impact of threats, such as entanglement in fishing gear, infectious disease or toxic pollutants upon cetacean populations. Nevertheless, careful statistical analyses of the aggregated data between 1990-1999 have allowed us to draw some important conclusions about the relative importance of these threats and the need for future research.

Between 1990-1999, 737 cetacean carcases from England and Wales were examined at postmortem. A cause of mortality was established in 563 of these animals. By far the most frequent cause of mortality was entanglement in fishing gear representing nearly half (48%) of cases where a cause of mortality was established. Statistical analyses showed that a greater number of harbour porpoise by-catches were juveniles rather than adults or neonates. This may indicate that immature individuals are more vulnerable to by-catch related mortality, and that a degree of learning may be involved in the avoidance of entanglement in fishing gear. Common dolphins and harbour porpoises diagnosed as by-catches were also typically in good health and nutritional status.

By-caught porpoises were most frequently recorded in Wales, South-west England (Cornwall and Devon) and along the North Sea coastline from Northumberland to Humberside. In contrast, by- caught common dolphins were mainly recorded in South-west England. By-catch was also markedly seasonal within Cornwall and Devon with more porpoises and common dolphins stranding between January to April. This seasonal pattern of high by-catch related mortality in both stranded common dolphins and harbour porpoises within Cornwall and Devon may be due to factors such as seasonal changes in the distribution of these species and their prey or changes in fisheries effort.

Future research should include continued monitoring of cetacean mortality using standard procedures on a European scale, investigations into interactions between fisheries and cetacean populations, genetic studies of population structure, and investigations into the importance of toxic contaminants as causes of immunosuppression and endocrine disruption in cetaceans. 1. Introduction

1.1 Aim

The aim of the project is to investigate the causes of disease and death in cetaceans stranded around the coasts of England and Wales, as part of a UK programme of research.

1.2 Policy background

The UK has over 20 cetacean species present in its coastal waters, and has taken a number of measures over the years to protect them. All species are protected against intentional killing, injury, capture or disturbance under the Wildlife and Countryside Act 1981, and since October 1994 are further protected under The Conservation (Natural Habitats, &c.) Regulations 1994 which implement the EC Habitats Directive (92/43/EEC). The UK is a Party to the Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas (ASCOBANS), a regional agreement under the "Bonn" Convention on Migratory Species of Wild Animals, which came into force on 29 March 1994. Under the Agreement, range states are committed to cooperate in research, management and other measures needed to conserve dolphins, porpoises and other small cetaceans in the North Sea (including the English Channel) and the Baltic. The UK Government is applying the spirit of the Agreement in all UK waters. The Department is the UK Co-ordinating Authority for implementation of the Agreement and, as such, has primary responsibility for ensuring the conservation of the species. Through a number of different Departments, including DETR, the Government finances a number of research projects intended to provide knowledge on what further measures may be needed to conserve these populations. Much of the work, including population surveys, needs to be undertaken on a European scale and the Agreement is designed to allow this. The Conservation and Management Plan that forms an integral part of the ASCOBANS Agreement specifically requires that

"Each Party shall ... establish an efficient system for ... retrieving by-catches and stranded specimens and to carry out ... full autopsies in order to collect tissues for further studies and to reveal possible causes of death and to document food composition. The information collected shall be made available in an international database."

The Plan also requires Parties to work towards development of fishing gear and modifications in fishing practices to reduce by-catch and to identify threats to cetaceans. The Habitats Directive also requires EU Member States to monitor the incidental capture and killing of cetaceans. To this end, DETR established four complementary and integrated contracts during the period 1991 to 1993: strandings co-ordination in England and Wales; strandings co-ordination in Scotland; recording and collation of strandings information, and development of a database to manage information coming from strandings investigations. At the start of the 1995/96 FY responsibility for this Cetacean Strandings Programme was transferred from Water Directorate to Wildlife and Countryside Directorate, the latter having responsibility for ASCOBANS. Seals are also protected against certain methods of killing under The Conservation (Natural Habitats, &c.) Regulations 1994. Autopsies of seals are valuable in providing an additional sample for the analysis of contaminants or disease in marine mammals, and they were included in the above projects.

1.3 Achievements of the project in relation to the objectives set out in the contract

Objective 1. To continue to manage and carry out the investigation of marine mammal (cetaceans and seals) strandings and by-catches in England and Wales in close co-operation with the Natural History Museum and other participating and interested bodies. Emphasis and priority for resources will be given to cetaceans.

This objective was achieved successfully. Section 2 describes the methods used including the management and personnel involved (2.1) and details of collaboration with other organisations (2.3).

Objective 2. To maintain strategies, protocols and arrangements for the investigation of marine mammal strandings and the collection of samples necessary for studies of cetacean biology and health.

This objective was achieved successfully. Section 2 describes the methods used including the standard protocols for reporting of strandings, post-mortem investigation and tissue sampling (2.2, Appendices 2 and 3).

Objective 3. To monitor the causes of disease and death in marine mammals and changes in their patterns of incidence.

This objective was achieved successfully. Tables 3.1 to 3.3 and Appendix 1 summarise the results of the post-mortem investigations. Section 3 describes the analyses of the causes of mortality in cetaceans (3.1) and grey seals (3.2) found during the current contract 1995-2000.

Objective 4. To maintain the Poseidon database for the pooling and exchange of data between collaborating organisations.

This objective was achieved successfully. Section 2.4 describes the Poseidon central database and Tables 2.1 and 2.2 summarise the current content of the database.

Objective 5. To use the Poseidon database to produce an integrated analysis of the pooled data on, and coming from, marine mammal strandings, and to deliver UK contributions to the international database required by ASCOBANS.

This objective was achieved successfully. Tables 3.1 to 3.3 summarise the results of the post- mortem investigations. Section 3 describes the analyses of the causes of mortality in cetaceans (3.1) and grey seals (3.2) found during the current contract 1995-2000. Section 4 describes the results of analyses of pooled data on patterns of harbour porpoise mortality during the period 1990-1999 (4.1), studies of the pathology and epidemiology of cetacean diseases (4.2), and the possible relationships between contaminants and health status in harbour porpoises (4.3).

Objective 6. To maintain a marine mammal tissue archive and record the location of all samples taken from stranded and by-caught marine mammals. This objective was achieved successfully. Section 2.4 describes the tissue archive and Table 2.1 the current holdings.

Objective 7. To collect and make available appropriate tissue samples from selected species to researchers for the purposes of determining and monitoring tissue contaminant levels and disease incidence.

This objective was achieved successfully. Details of collaborations using the tissue archive are detailed in Section 2.3.

Objective 8. To advise the Department, other Government Departments, and other bodies on the significance of, and responses to, marine mammal mortality incidents.

This objective was achieved successfully. The reporting of data collected in the course of this work is described in Section 2.5.

Objective 9. To liaise closely with other contractors in the Cetacean Strandings Programme, and those carrying out similar work in Northern Ireland, to ensure that all work contributes to a coherent UK approach.

Details of the close links between the collaborating organisations are given in Section 2. 2. Methodology

2.1 Management and personnel

Peter Bennett (BSc DPhil) is the Principal Investigator and Contractor`s Nominated Officer. He is the grant holder with overall responsibility for the management of staff, research and budgets. His post is wholly funded by the HEFCE core grant to the Institute of Zoology (IoZ). James Kirkwood (BVSc PhD MRCVS RCVS) held this position until his departure from IoZ in 1996. Two posts at IoZ are funded by this contract. Paul Jepson (BVMS MRCVS) is the Marine Mammal Strandings Co-ordinator. He has responsibility for co-ordinating the network of people and organisations who report stranded animals and conduct post-mortem investigations. He also conducts post-mortems on animals at the IoZ. The second post is held by Robert Deaville (BSc) who is the Research Assistant. He has responsibility for managing the Poseidon central database, the frozen and fixed tissue archives and assists during the post-mortems conducted by Paul Jepson. A number of key collaborators work on this project but their salaries are not funded by it. These are Shaheed Magregor who performs microbiological analyses at the IoZ; Bill Holt who collaborates on studies on the reproductive biology of cetaceans at IoZ; John Baker who performs post-mortems at the Veterinary Field Station, University of Liverpool; Vic Simpson who performs post-mortems at the Veterinary Investigation Unit, Polwhele, Cornwall; Robin Law and Colin Allchin, who perform toxicological analyses at the Centre for Environment, Fisheries and Aquaculture Science, Burnham Laboratory, Burnham-on-Crouch. Other collaborating organisations and scientists are detailed below in Section 2.3.

2.2 Protocols for reporting of strandings and post-mortem investigation

The research methods used to meet the objectives were developed during the three previous contracts to IoZ between 1990-95 for investigating marine mammal strandings. These methods have continued to be applied throughout the period of the current contract to ensure that data is collected and recorded in a standardised manner. In this way, we were able to ensure that the ‘best practise’ was applied in the investigation of each stranded animal and that standardised information could be aggregated for investigating patterns of mortality.

2.2.1 Reporting of marine mammal strandings

The Natural History Museum (NHM) has kept ongoing records of cetacean strandings within the United Kingdom since 1913. IoZ has maintained records of seal strandings within the UK since 1990. The reporting, retrieval and transportation of marine mammal carcasses within England and Wales involves the integration of a number of localised reporting centres with the Institute of Zoology and the Natural History Museum (see below). IoZ works closely with the NHM and other organisations to ensure that cetacean carcasses (and a small number of seal carcasses) that are suitable for post-mortem examination are promptly and successfully retrieved. The decision about whether to post-mortem a carcass is based on the state of decomposition and whether it can be secured safely prior to collection and transportation to a laboratory for post-mortem examination. The relevant public health considerations of handling stranded marine mammal carcasses are stressed to those individuals and organisations that are involved with the day-to-day reporting and recovery of stranded marine mammal carcasses. Central reporting centres

The Natural History Museum, Cromwell Road, London, SW7 5BD. Tel: 020 7942 5155. Records all UK cetacean strandings (since 1913) and accords reference numbers. Transports some cetacean carcasses within England to the Institute of Zoology for postmortem examination. Institute of Zoology, Zoological Society of London, Regent`s Park, London NW1 4RY. Tel: 020 7449 6691. Receives reports of marine mammal strandings within England and Wales. Records seal strandings within the UK and administers national reference numbers.

Regional Reporting Centres

Marine Environmental Monitoring, Penwalk, Llechryd, Ceredigion SA43 2PS. National Strandings Line for Wales 01348 875000. Co-ordination of all marine mammal strandings in Wales by Rod Penrose. Sub-contracted to the Natural History Museum (under Welsh National Assembly Contract 003/95).

Cornwall Wildlife Trust, Five Acres, Allet, Truro, Cornwall TR4 9DJ. Tel: 01872 723939 or 01209 712069. Co-ordinates all marine mammal strandings within Cornwall.

National Marine Aquarium, The Fish Quay, Plymouth PL4 0LH. Tel: 01752 600301. Reporting and collection marine mammal carcasses within the Dorset/Devon area.

2.2.2 Reporting of live cetacean strandings

There has been increasing concern about the welfare of live marine mammal strandings within the UK. Although a number of rehabilitation centres have now been established for the nursing of sick or injured seals and seal pups (such as the RSPCA Wildlife Hospital in Norfolk), there was until recently little provision for cetaceans. A coalition of several welfare and rescue groups or societies called the Marine Animal Rescue Coalition (MARC) has been established to provide a forum for the exchange of information, expertise and resources, and to help develop a more coherent and integrated strategy of response to live strandings of cetaceans. A key outcome of MARC meetings held during the period of this contract (a number of which were attended by IoZ), was the acknowledgement that fast response of veterinary assistance and rescue equipment to the stranded cetacean(s) were critical to the successful management of any live cetacean stranding event. To this end, IoZ has been involved in three workshops for practising veterinary surgeons that were held on weekends. The first was in Dorset (near Southampton), the second in the Severn area (Bristol), and the third was in Wales (Aberaeron). IoZ has also been a contributor to the following publications designed to help provide critical information for veterinary surgeons and other rescue group personnel working in the field. Both publications have been approved by the Royal College of Veterinary Surgeons. a) Stranded cetaceans: guidelines for veterinary surgeons (produced and published by the RSPCA) b) The Marine Mammal Medic Handbook (produced by British Divers Marine Life Rescue)

In the event of any sick seal or live stranded cetacean being found, the nationally agreed first point of contact is the RSPCA 24hr emergency contact telephone number. The RSPCA (24hr) emergency number is 0870 5555999

2.2.3 Pathology laboratories

The majority of post-mortem examinations were carried out at one of the following three pathology laboratories.

Institute of Zoology (Department of Veterinary Science). Post-mortem examinations conducted on cetaceans (and occasional seals). IoZ also provides back-up for pathologists in collaborating laboratories as required and conducts histological examination of tissues from postmortem examinations conduced in London and in Cornwall by the VIU (Polwhele).

Veterinary Investigation Unit, Polwhele, Truro, Cornwall. Cetacean (and occasional seal) gross postmortem and bacteriological examinations on carcasses stranded within Devon and Cornwall. Samples collected for laboratory investigation other than bacteriological examination are routinely sent to IoZ for further analyses, archiving, or distribution to the appropriate organisation.

University of Liverpool, Neston Field Station (Wirral). Conducts post-mortem investigations on cetaceans and seals stranded within Wales and NW England. Perform gross post-mortem examinations and histological examinations on samples taken from those carcasses. Bacteriological examinations are also conducted at the University Field Station. Samples for other laboratory analyses were sent to the IoZ for tissue archiving and distribution to other collaborating institutions.

2.2.4 Standard protocols for postmortem examination, tissue sampling and data recording

The fundamental basis of this contract is that each laboratory conducts post-mortem investigations, tissue sampling and recording of observations using standard procedures. The standardised post- mortem examination guidelines (Appendix 2a), and report forms (Appendix 2b) for cetaceans and the standard UK postmortem examination guidelines (Appendix 3a) and report forms (Appendix 3b) for seals were used for all marine mammal postmortem examinations conducted under this contract. Carcasses were routinely transported to one of the three pathology laboratories (IoZ, University of Liverpool, Veterinary Investigation Unit Polwhele) conducting postmortem investigations under the contract. In cases where carcasses were too large or too difficult to retrieve, postmortem investigations were conducted at the stranding site in situ.

Virological examinations. Routine samples from standard tissue sites were preserved at -700C together with samples of any lesions suspected to be of possible viral origin. Formalin-fixed samples of lung tissue were also routinely collected and sent Dr Seamus Kennedy, Veterinary Sciences Division, Department of Agriculture for Northern Ireland in Belfast for immunoperoxidase screening for the presence of morbillivirus antigen. Bacteriological examinations. Routine samples were taken from specified tissues for bacteriological culture, together with any lesions suspected to be of bacterial (or mycotic) aetiology, according to the standardised postmortem protocols . All three pathology laboratories (IoZ, University of Liverpool, Veterinary Investigation Unit Polwhele) conducting postmortem investigations under this contract conducted bacteriological examinations on site.

Histological examinations. Tissues collected for histological examination from postmortem examinations conducted at IoZ and at the Veterinary Investigation Unit (Truro), Cornwall were trimmed at IoZ and then sent to the Histology Department of the Royal Free Hospital, Pond Street, London NW3 2QG for processing. Dr. John Baker conducted histological examinations of tissues collected during postmortem examinations conducted at Veterinary Field Station (University of Liverpool). All standard formalin-fixed tissue samples collected from postmortem examinations conducted under this contract were archived at IoZ.

Tissue archives. The tissue specimens collected for research and archive are detailed in Table 2.1. They include a comprehensive range of tissue samples stored at both -200C and -700C and in 10% neutral buffered formalin or 70% alcohol. All these tissues are archived within the marine mammal tissue archive held at the Institute of Zoology or sent to collaborating institutions for research purposes. Table 2.1 Summary of material held in the marine mammal tissue archive at IoZ

Poseidon Archive Title Material/Storage Location/Research Aim No. of Total method samples 1990-2000 1995-2000 ARCHIVE Skin (Frozen) IOZ (Archived for DNA studies) 400 700 ARCHIVE Scapula (Frozen) RMS (For morphometric analysis) 217 573 ARCHIVE Rib (Frozen) IOZ (Lead/radionuclides analysis) 305 714 ARCHIVE Skull (Frozen) RMS (For morphometric analysis) 131 353 ARCHIVE Miscellaneous IOZ (Includes thymus, lungs, foetuses, 606 1351 (Frozen) muscle, etc) FIXED Ovary (Fixed) IOZ (Archived for future reproductive 182 323 studies) FIXED Testis (Fixed) IOZ (Archived for future reproductive 133 341 studies) FIXED Adrenal gland IOZ (Archived for future 249 780 (Fixed) histopathological studies) FIXED Brain (Fixed) IOZ (Archived for future 90 108 histopathological studies) FIXED Ear Bones (Fixed) IOZ (Archived for future studies) 125 125 FIXED Miscellaneous IOZ (Includes eyes, lungs, hearts etc) 23 111 (Fixed) HISTOPATHOLOGY Miscellaneous IOZ (All material stored in original wax 2337 4356 (Fixed and blocks and also as processed slides) sectioned) MORBILLIVIRUS Lung (Fixed) IOZ (Temporary storage) 282 496 BELFAST (See below) MISCELLANEOUS Miscellaneous IOZ (Includes dorsal fins, baleen, 84 387 (Frozen and ambient blubber, milk, nets found with temperature) carcasses, vertebrae etc) PARASITES Parasites (Fixed in IOZ (Temporary storage) 527 1634 70% ethanol) NHM (Sent for classification at regular intervals) SERUM Serum/Heart Blood IOZ (Aliquots archived for present and 212 398 (Frozen) future serological studies) STOMACH Whole stomachs IOZ (Temporary storage) 153 784 and stomach UCC (For porpoise stomach contents) contents (Frozen NHM (For other cetacean stomach and also Fixed in contents) 70% ethanol) TEETH Teeth (Frozen) IOZ (Temporary storage) 275 776 UCC Age porpoise teeth NHM Age other cetacean teeth TOXICOLOGY Blubber, Muscle, IOZ (Archived and duplicate samples) 520 1174 Kidney and Liver CEFAS (Samples sent for analysis) (Frozen duplicates) 102 447 VIROLOGY Miscellaneous IOZ (Various tissues and lesions 428 549 (Frozen at -70oC) stored for future analyses.) LOCATION KEY IOZ - Institute of Zoology Marine Mammal Archive, CEFAS - Centre for Environment, Fisheries & Aquaculture Science, NHM - Natural History Museum, RMS - Royal Museum of Scotland, BELFAST - Dr Kennedy in Stormont, Belfast, UCC -University College Cork 2.3 Collaboration with other organisations

IoZ has maintained and initiated a number of collaborations with other organisations to both meet the objectives of the contract and to facilitate novel lines of research.

The Centre for Environment, Fisheries & Aquaculture Science, Burnham Laboratory, Remembrance Avenue, Burnham-on-Crouch, Essex. Tissue samples are routinely sent to this laboratory for toxicological studies, including analyses of organochlorine and heavy metals levels.

The Natural History Museum, Cromwell Road, London, SW7 5BD. Teeth ageing (cetaceans other than porpoises), stomach content identification (cetaceans other than porpoises), parasite identification (all cetaceans).

Dr. Seamus Kennedy, Veterinary Sciences Division, Department of Agriculture for Northern Ireland, Stormont, Belfast. Fixed samples of cetacean lung tissue are routinely sent to Dr. Kennedy for immunoperoxidase screening for the presence of morbillivirus antigen.

Dr. Emer Rogan, Department of Zoology and Animal Ecology, University College Cork, Republic of Ireland. Teeth and stomach contents from harbour porpoises are sent for teeth ageing and stomach content analysis respectively.

Dr Andrew Kitchener, Royal Museum of Scotland, Edinburgh, Scotland. Marine mammal skulls and scapulae are sent to Dr. Kitchener for marine mammal morphometric studies.

Dr. Marie-Francoise Van Bressem, Institute of Animal Health, Pirbright, Surrey. Serological analyses of cetacean and seal serum samples for morbillivirus antibody titres, using indirect ELISA and virus neutralisation assays.

Dr. Paul Thompson, University of Aberdeen, Department of Zoology, Lighthouse Field Station, George Street, Cromarty, Ross-shire IV11 8YJ. Skin samples from bottlenose dolphins for genetic analyses.

2.4 Tissue archive and Poseidon central database

The tissue archive and Poseidon central database were developed under previous contracts to IoZ for marine mammal strandings investigation. The aim of the tissue archive is to provide an extensive range of tissues for retrospective analyses while the central database was established to ensure that the information collected by the different collaborating laboratories and individuals is recorded centrally, accurately, securely and in a standard manner. In this way collaborative analyses of the pooled data, the production of reports and the management of the tissue archive are facilitated. Both the tissue archive and the Poseidon central database have expanded greatly during the course of this contract. The Poseidon central database record information on 7,181 individual marine mammals stranded in the British Isles. These records are summarised by species in Table 2.2. Of these, 934 have had a post-mortem conducted at the IoZ or at one of the collaborating institutions across England and Wales, since the beginning of DETR funded marine mammal research at IoZ in 1990. 359 of these post-mortems have taken place during the period of this contract (1995-2000). Table 2.2 Total number of individuals by species recorded in the Poseidon central database

Species Number recorded in Number investigated by Poseidon post mortem Harbour Porpoise (Phocoena phocoena) 1768 515 Common Dolphin (Delphinus delphis) 561 216 Striped Dolphin (Stenella coeruleoalba) 68 40 Atlantic White-Sided Dolphin (Lagenorhynchus acutus) 115 28 White-beaked dolphin (Lagenorhynchus albirostris) 223 25 Pilot Whale (Globicephala melas) 513 15 Bottlenose Dolphin (Tursiops truncatus) 275 14 Minke Whale (Balaenoptera acutorostrata) 185 7 Risso’s Dolphin (Grampus griseus) 123 6 Sowerby’s Beaked Whale (Mesoplodon bidens) 55 6 Sperm Whale (Physeter macrocephalus) 51 2 Fin Whale (Balaenoptera physalus) 45 2 Blainsville’s Beaked Whale (Mesoplodon densirostris) 1 1 Killer Whale (Orcinus orca) 64 1 Pygmy Sperm Whale (Kogia breviceps) 3 1 Northern Bottlenose Whale (Hyperoodon ampullatus) 72 1 Sei whale (Balaenoptera borealis) 12 0 Blue whale (Balaenoptera musculus) 4 0 Humpback whale (Megaptera novaeangliae) 2 0 True’s beaked whale (Mesoplodon mirus) 3 0 Narwhal (Monodon monocerus) 2 0 False Killer whale (Pseudorca crassidens) 75 0 Goose beaked whale (Ziphius cavirostris) 46 0 Cetacean (Species indeterminate) 706 1

Grey seal (Halichoerus grypus) 1170 170 Common seal (Phoca vitulina) 448 51 Hooded seal (Cystophora cristata) 3 1 Harp seal (Phoca groenlandicus) 1 0 Ringed seal (Phoca hispida) 1 0 Seal (Species indeterminate) 586 4

TOTAL 7181 1107

The remainder (6247 records) are either retrospective or historical data (information gained from the strandings records published by the Natural History Museum) or ones where a post mortem has not been conducted, but samples have been collected for the project (for example skin samples for future DNA analysis or teeth for ageing). This information may be useful in comparing any patterns of mortality found during the course of the project with historical data. The IoZ also maintains the records for all seal species stranded throughout the UK, allocating seal stranding numbers as required and monitoring any unusual patterns of mortality. The Poseidon database is used to keep track of all samples taken from animals during the course of a post-mortem, which are then stored in the Marine Mammal tissue archive at the IoZ. Details of this archive, with reference to storage and location of samples, together with information on research purposes is given in Table 2.1. This information is stored on the Poseidon database in separate files, all linked to the central database through the Natural History Museum reference number which is unique to each animal. This enables the cross indexing of animals with their samples, to take place upon request. Currently, twelve freezers (one of which is a -700C freezer, holding samples taken for virological analysis) are used to store material gathered during the course of this project. In addition, some samples are stored fixed in 10% neutral buffered formaldehyde for future histopathological studies, while parasites and some stomach contents are stored fixed in 70% ethanol. All of these samples, as well as some miscellaneous material (e.g. nets found entangled around carcasses) are held at IoZ in a secure location which is checked daily in case of freezer malfunction.

2.5 Reporting of data

Data resulting from this contract has been routinely reported to the Department through annual contract progress reports. In addition, regular reports have been submitted to ASCOBANS OGD meetings. Annual data on numbers of strandings of each cetacean species examined, together with the main causes of death, have also regularly been submitted to the Departments` Digest of Environmental Statistics (Wildlife Chapter). Occasionally, data have also been submitted to the Department for the purposes of answering Parliamentary Questions. A number of manuscripts reporting some of the findings resulting from work conducted under this contract have been published within the scientific literature (see Section 7).

2.6 Training

Paul Jepson has been studying part time for a PhD during the period of this contract. His doctoral research is supervised by Dr’s Bennett and Holt (Institute of Zoology) and Prof. Noakes (Royal Veterinary College).

The Institute of Zoology conducts an MSc in Wild Animal Health course. Five MSc projects were awarded during the period of the present contract which have been supervised by Dr Peter Bennett, Dr Bill Holt and Mr Paul Jepson. The titles of these projects are:

A histopathological study of the possible effects of mercury contamination in the liver of harbour porpoises (Phocoena phocoena) from British waters. Julie Barnes, BVSc, MRCVS. 1995

The use of histochemical techniques to investigate development and seasonality in the male harbour porpoise (Phocoena phocoena). Angela McMullan, BVetMed, MRCVS. 1996

Aspects of testis development and morphology in the male harbour porpoise (Phocoena phocoena). Hisako Ohira. 1996

Lungworm abundance and respiratory pathology of harbour porpoises (Phocoena phocoena) in British waters. Gidona Goodman, MRCVS. 1997

A study of life history variation in cetaceans using the comparative method. Satoko Kawazu. 1998 3. Results

3.1 Causes of mortality in cetaceans

During the period of this contract, 359 postmortem examinations of marine mammals stranded or by-caught (in commercial fisheries) within England and Wales were conducted, comprising 326 cetaceans of 14 different species, and 33 grey seals (Halichoerus grypus). The number of postmortem examinations of each cetacean species are shown in Table 3.1. A list of the references numbers, biological data, date, location and cause of death for all stranded cetaceans examined during the period of this contract (1995-2000) is shown in Appendix 1a. A similar list is provided for stranded seals in Appendix 1b. The main causes of death will be discussed separately and are summarised in Table 3.2. The cumulative total of animals of each species examined at postmortem, and their causes of death, for the 9 year period of DETR-funded strandings research (1990-1999) are reported in Table 3.3. Plates illustrating aspects of these results are included at the end of this report.

3.1.1 Entanglement in fishing gear (by-catch)

During the period of this report, 64 stranded harbour porpoises, 32 common dolphins, one striped dolphin, one white beaked dolphin and one pilot whale were diagnosed to have been fatally entangled in fishing gear (by-catch). In addition, 21 by-caught harbour porpoises were retrieved for postmortem examination from commercial fishing vessels (referred to as ‘physical trauma, bycatch(known)’ in Table 3.2) . Many of these known by-catches were reported through the EU- funded BYCARE research programme. By-catch was the most common cause of mortality in harbour porpoises and common dolphins throughout the period of this report. Excluding the 21 by-catches that were brought in from commercial fishing vessels, by-catch still accounted for the cause of death of 64 (41%) of the 156 stranded harbour porpoises where a cause of death could be established. The cumulative total of harbour porpoise by-catches from the start of DETR-funded strandings research in the UK (Sept 1990) to the end of 1999, excluding known by-catches retrieved from fishing vessels, was 119, which represented 39% of all established causes of death for stranded harbour porpoises during this period. Of the 75 stranded common dolphins examined at postmortem during the period of this report, by-catch accounted for the cause of death of 32 which represents 54% of those for which a cause of death could be established. The cumulative total of common dolphin by-catches from Sept 1990 to the end of 1999 was 118, which represented 71% of all established causes of death for stranded common dolphins during this period. The pathological criteria for the diagnosis of by-catch were developed at IoZ (Kuiken et al. 1994; Kuiken et al. 1996). The pulmonary lesions associated with harbour porpoise by-catches occurring between 1990 and 1996 have also been analysed (Jepson et al. 2000). The main difference between the pathology of by-catch in harbour porpoises and common dolphins was that harbour porpoises frequently presented with thin, linear cutaneous cuts or depressions on the leading edges of the pectoral fins, tail flukes and dorsal fin, or had similar lesions that sometimes partly or completely circumscribed the head. These lesions are considered to be due to entanglement in wide- meshed monofilament gillnet-type fishing gear (see Plates 12-14). The geographical distribution of by-catch related mortality in harbour porpoises contrasted with that of common dolphins. Stranded harbour porpoises diagnosed to have died due to by-catch were frequently recorded in Wales, South-west England (Cornwall and Devon) and along the North Sea coastline from Northumberland to Humberside. In contrast, stranded common dolphins that were diagnosed to have died due to by-catch were only frequently recorded in South-west England (Cornwall and Devon). Furthermore, a seasonal pattern of by-catch related mortality was observed in harbour porpoise and common dolphin strandings in Cornwall and Devon. Most harbour porpoise and common dolphin by-catches in Cornwall and Devon stranded during the period January to April, which contrasted sharply with the more year-round distribution of harbour porpoise by-catches in other regions such as Wales and north-east England.

3.1.2 Physical trauma

Physical trauma was diagnosed as the cause of death of 18 harbour porpoises, four common dolphins, two white beaked dolphins and one Risso’s dolphin during the period of this report. In many cases, the cause of the fatal traumatic injuries could not be identified. However, since 1995 nine stranded harbour porpoises (8 juveniles, 1 adult) had fatal traumatic lesions (see Plates 16-17) that were consistent with those first described in stranded harbour porpoises from the Moray Firth, Scotland and which have been attributed to lethal attack by bottlenose dolphins (Ross and Wilson 1996). All nine of these harbour porpoises stranded within Cardigan Bay, West Wales. Harbour porpoises have a sympatric distribution with a resident population of bottlenose dolphins within Cardigan Bay. The pathology of the first four of these harbour porpoises have been reported within the scientific literature (Jepson and Baker 1998). A harbour porpoise that died of physical trauma had injuries consistent with a fatal impact with a boat propeller.

Table 3.1 Stranded cetaceans examined at necropsy between April 1995 and December 1999 in England and Wales

Species 1995-1999 1990-1999

Harbour Porpoise (Phocoena phocoena) 215 437 Common Dolphin (Delphinus delphis) 75 212 Striped Dolphin (Stenella coeruleoalba) 15 32 White-beaked dolphin (Lagenorhynchus albirostris) 8 18 Bottlenose Dolphin (Tursiops truncatus) 1 7 Atlantic White-Sided Dolphin (Lagenorhynchus acutus) 1 6 Pilot Whale (Globicephala melas) 2 7 Risso’s Dolphin (Grampus griseus) 2 5 Fin Whale (Balaenoptera physalus) 1 2 Minke Whale (Balaenoptera acutorostrata) 2 4 Sperm Whale (Physeter macrocephalus) 0 2 Blainsville’s Beaked Whale (Mesoplodon densirostris) 0 1 Killer Whale (Orcinus orca) 1 1 Pygmy Sperm Whale (Kogia breviceps) 1 1 Sowerby’s Beaked Whale (Mesoplodon bidens) 1 1 Northern Bottlenose Whale (Hyperoodon ampullatus) 1 1

TOTALS 326 737 Table 3.2 Causes of death over the period of the present grant (April 1995-December 1999)

Cause of death category Harbour Common Striped Other Total porpoise dolphin dolphin cetaceans Bycatch 85 32 1 2 120 Pneumonia 12 2 0 0 14 Physical trauma 18 4 0 3 25 Starvation 16 2 2 5 25 Live stranding 17 12 3 7 39 Generalised bacterial infection 12 0 0 1 13 Gastropathy & Enteropathy 4 3 1 1 9 Dystocia & Stillborn 4 0 0 1 5 Meningoencephalitis 1 0 0 0 1 Neoplasia 1 0 0 0 1 Morbillivirus 0 0 0 0 0 Others 7 4 1 0 12

Not established 38 16 7 1 62

TOTAL 215 75 15 21 326

Table 3.3 Causes of death over the total period of the DETR funded research at IoZ (September 1990-December 1999)

Cause of death category Harbour Common dolphin Striped dolphin Other Total porpoise cetaceans Bycatch 143 118 1 8 270 Pneumonia 41 8 1 2 52 Physical trauma 39 4 4 12 59 Starvation 35 3 1 5 44 Live stranding 18 19 7 12 56 Generalised bacterial Infection 17 1 0 1 19 Gastropathy & enteropathy 11 3 1 2 17 Dystocia & stillborn 8 0 0 2 10 Meningoencephalitis 4 0 0 0 4 Neoplasia 3 0 0 0 3 Morbillivirus 1 0 0 0 1 Others 13 9 3 3 28

Not established 104 47 14 9 174

TOTAL 437 212 32 56 737 3.1.3 Infectious disease

Infectious diseases were common causes of mortality in harbour porpoises, accounting for the death of 26 harbour porpoises during the period of this report. The most common causes of mortality due to infectious diseases in harbour porpoises were pneumonias (parasitic and bacterial) and generalised bacterial infections. Infectious disease mortality was rarely recorded within strandings of other cetacean species.

Generalised bacterial infections

Generalised bacterial infections caused the death of 12 harbour porpoises during the period of this report. The agents responsible for these fatal septicaemias were Streptococcus canis (n=5), Group B Salmonella sp. (n=2), Listonella damsela (n=2), Morganella morgani (n=1), Mycobacterium fortuitum (n=1). In one case the bacterial agent could not be fully identified. Generalised bacterial infections involving Streptococcus canis often produced widely disseminated abscessation throughout the carcass. A peracute generalised bacterial infection with Erysipelothrix rhusiopathiae also caused the death of one female adult bottlenose dolphin.

Pneumonias

Pneumonias due to combinations of parasitic, bacterial and mycotic agents were recorded in nine harbour porpoises during the period of this report. Pneumonia of undetermined aetiology was also recorded as the cause of death for three additional harbour porpoises. Harbour porpoises typically develop pulmonary infections with several different species of nematode parasites after weaning (around one year of age), and these nematodes are pathogenic producing a range of parasitic lesions within the bronchi, alveoli and pulmonary vasculature. It is probable that some parasitised animals that also developed concurrent bacterial or mycotic pneumonias did so as secondary infections resulting from nematode-induced damage to the lungs. A detailed study of the pathology of pneumonias and other pulmonary diseases recorded in harbour porpoises stranded and examined at postmortem within England and Wales between September 1990 and December 1996 was conducted (Jepson et al. 2000). The findings of this study are summarised elsewhere within this report. A single case of pneumonia of undetermined aetiology was also recorded as the cause of death of one common dolphin.

Other causes of infectious disease mortality

Other causes of infectious disease mortality were recorded within the period of this contract. In harbour porpoises, mortality due to parasitic gastritis (n=2), gastric stenosis (parasitic)(n=1), parasitic asphyxiation (n=1), necrotising enteritis/peritonitis associated with Salmonella sp. infection (n=1), and non-suppurative meningitis of probable infectious aetiology (n=1) were recorded. Within common dolphins, parasitic gastritis (n=1), heavy gastric parasitism (n=1) and peritonitis associated with intestinal rupture (n=1). A striped dolphin died due to heavy gastric parasitism and an Atlantic white-sided dolphin died due to parasitic gastritis. No cases of morbillivirus were diagnosed in any species during the period of this contract report. 3.1.4 Starvation

Individuals were considered to have died due to starvation if they were found on postmortem examination to be in an emaciated condition but without evidence of severe underlying disease. Maternal separation was considered a probable cause of starvation in emaciated neonates and calves that would still have been maternally dependent at death. Animals that died of starvation comprised 16 harbour porpoises (including 9 neonates), two common dolphins (including one calf), two white beaked dolphins, two minke whales (both calves), two striped dolphins and one killer whale.

3.1.5 Live stranding

During the period of this report 33 cetacean carcasses examined at postmortem were known to have stranded alive prior to death and another 43 cetaceans were suspected (from subsequent postmortem examination) to have also live stranded. These comprised 44 harbour porpoises, 17 common dolphins, five white beaked dolphins, three striped dolphins, two minke whales and single strandings of a pigmy sperm whale (Kogia breviceps), a pilot whale (Globicephala melas), a Sowerby’s beaked whale (Mesoplodon bidens), a killer whale (Orcinus orca) and a northern bottlenose whale (Hyperoodon ampullatus). The cause of death in these individuals was only attributed to “live stranding” if the postmortem examination failed to demonstrate evidence of severe underlying disease. If animals that were known or suspected to have live stranded had significant underlying disease on postmortem examination, the cause of death was attributed to the disease processes identified and the animal was considered to have live stranded in extremis. Lesions consistent with live stranding included fresh cutaneous haemorrhagic abrasions on the lower jaw and the leading edges of the pectoral fins and/or tail flukes, hypostatic congestion (most notably pulmonary hypostasis which was often also unilateral), and agonal ingestion of beach material. Carcasses of live stranded cetaceans also typically presented for postmortem examination in a very fresh state of preservation with little or no evidence of scavenger damage. Using these criteria live stranding was considered the cause of death for 17 harbour porpoises, 12 common dolphins, three striped dolphins, three white beaked dolphins, and single strandings of a pigmy sperm whale, a pilot whale, a Sowerby’s beaked whale, and a northern bottlenose whale.

3.1.6 Dystocia and Stillborn

Dystocia (difficulty in parturition) was considered the cause of death of four adult female harbour porpoises and a neonatal Rissoles dolphin.

3.1.7 Neoplasia

There has been a low prevalence of neoplasia recorded in cetaceans both during the period of this report and since the beginning of strandings research in 1990. A very decomposed carcass of a harbour porpoise had tumour-like masses within the lungs and lymph nodes that were suspected to be neoplastic, although the degree of decomposition prevented more detailed characterisation of the lesions. 3.1.8 Other causes of death

Other causes of death in harbour porpoises included pulmonary fibrosis (n=2), acute pulmonary haemorrhage (n=1), parasitic asphyxiation (n=1), heavy generalised parasitism (n=1), congestive heart failure (n=1), and blood loss of unknown cause (n=1). Hydrocephalus (n=2), senility (n=1) and acute peritonitis (n=1) were diagnosed as the probable cause of death in four common dolphins. Fibrino-purulent pericarditis was considered to have the caused of death of a striped dolphin.

3.2 Causes of mortality in grey seals

During the period of this report 33 grey seals were examined at post-mortem. Of these, 20 stranded in Wales, eight in Merseyside and three in Cornwall with single strandings occurring in Devon and Greater London. The cause of death was not established for five of these individuals. Of the remaining 28, the causes of mortality were starvation (n=6), generalised bacterial infections (n=5), dystocia (n=3), heart failure (n=2), peritonitis (n=2) and one case each of physical trauma, by-catch, neoplasia, pneumonia, hydrocephalus, osteomyelitis, myositis, pleurisy, asphyxia due to inhalation of vomit, and euthanasia. 4 Results of analyses of pooled data

4.1 Patterns of harbour porpoise mortality 1990-1999

Between September 1990 and December 1999 inclusive, 437 harbour porpoise carcasses from England and Wales were examined at post-mortem. The cause of death could not be established for 104 individuals. The remaining 333 harbour porpoises were grouped, where possible, into the following cause of death categories: by-catch, physical trauma, all infectious disease (including two subgroups: pneumonias of infectious aetiology, and generalised bacterial infections), neonatal starvation, dystocia/stillborn and live stranding. These results are shown in Table 3.3. A careful statistical analysis was performed to investigate possible associations between these cause of death categories and the following biological variables: age category, year of stranding, sex, season, geographical location of stranding and nutritional status (body weight/body length ratio and mean blubber thickness). Briefly, chi-squared tests of association were used to establish whether the distribution of categorical variables were significantly different from those predicted by chance, linear regression and analysis of variance models were used to analyse categorical and continuously distributed data. The statistical methods and detail will be published fully in the scientific literature. Here we summarise the main results and conclusions.

The dataset A cause of death was established for 333 harbour porpoises. Across all these individuals, more neonates stranded in the summer months (April-September) than in the winter months (October-March) due to the seasonality of reproduction in harbour porpoises. No other statistically significant associations were found between the sex, age category, year of stranding, season of stranding or stranding region. These results suggest that there are few underlying systematic biases in the dataset.

By-catch 143 harbour porpoises were known or diagnosed to have died due to by-catch between September 1990 and December 1999. Statistical analyses showed that significantly more juvenile harbour porpoises were by-caught than adults and neonates which may suggest that juveniles are more vulnerable to by-catch due to their inexperience of avoiding nets. In addition, more by-caught porpoises stranded during January-March than at other times of the year. This was largely due to a strong seasonal effect of increased by-catch strandings in Cornwall and Devon during these months compared to other regions within England and Wales. This strong seasonal pattern of high by-catch related mortality in stranded harbour porpoises as well as common dolphins within Cornwall and Devon may be due to factors such as seasonal changes in the distribution of these species (and their prey) or changes in fisheries effort. Juvenile harbour porpoise by-catches had thicker blubber layers than adults and neonates, which may relate to the greater surface area to volume ratio of smaller juvenile animals resulting in a greater need for insulation compared to adults. The need for greater insulation in the winter is also the most obvious explanation for the finding that by-catches stranded between October and March had thicker blubber than those stranded between April and September. Blubber thickness was at its maximum thickness during January-March.

Infectious disease mortality 64 harbour porpoises were diagnosed to have died due to infectious diseases between September 1990 and December 1999. The frequency of infectious disease mortality was higher among adults (n=34) than juveniles (n=26) with the fewest cases occurring among neonates (n=4). The difference between adults and juveniles was not statistically significant. More porpoises died of infectious diseases in the winter months (October-March) than in the summer (April-September) which suggests that colder water temperatures in winter act as an extra stressor. More animals died of infectious disease in Wales and the east coast of England than in Cornwall/Devon and the English Channel. This is probably due to the low numbers of strandings in general in the Channel together with the high number of (largely seasonal) by-catches occurring within Cornwall and Devon. More porpoises died of infectious disease in Wales than on the east coast of England during January-March, and more porpoises died of infectious disease on the east coast of England than in Wales during July-September. The nutritional status of porpoises in the infectious disease group was better during the winter months (January-March) than other times of the year. These effects are also probably due to the colder winter water temperatures acting as an additional stressor in the disease process. Porpoises from Wales had poorer nutritional status than those from the east coast of England which may be due to differences in water temperatures between these regions, or may possibly reflect morphological differences between different sub- populations.

Pneumonias The infectious disease group was further sub-divided into a group comprising the animals that died of pneumonias of infectious aetiology (parasitic, bacterial, parasitic and bacterial and mycotic pneumonias). Within this group of 41 individuals, more adults died of pneumonia than other age groups with neonates being the least affected. There were more cases of fatal pneumonia recorded in individuals stranded in Wales and along the east coast of England than there were in south west England (Cornwall and Devon).

Generalised bacterial infections There were 17 cases of fatal generalised bacterial infections in harbour porpoises. More cases stranded between October-March than between April-September and on the east coast of England than in either Wales or Cornwall and Devon.

Mortality due to bottlenose dolphin attack Nine animals were diagnosed to have died due to attack from bottlenose dolphins. There were age and geographical biases within this group, with all cases stranding in Wales of which 8 were juvenile and one was an adult.

Perinatal and neonatal mortality A group of 35 individuals comprising neonates that died of starvation (n=27) plus adult females (n=4) and neonates that died of dystocia (n=4) was formed to test for patterns in neonatal and perinatal mortality. Virtually all cases of neonatal and perinatal mortality occurred in the summer between April and September which accords with the known seasonality of calving in harbour porpoises in UK waters. More cases stranded in Wales than on the east coast of England or within Cornwall and Devon, which may indicate that Cardigan Bay/West Wales is an important breeding and calving (nursery) ground for harbour porpoises.

Live strandings There were 18 harbour porpoises that were either known, or diagnosed, to have stranded alive during the period of this study, and that were otherwise in relatively good health status. Of these, more stranded on the east coast of England than in other regions. This may reflect differences in topography between the east and west coastline of England and Wales, with the longer inter-tidal ranges and shallower coastline of the east coast possibly being more difficult to navigate.

Comparisons of by-catch and infectious disease mortality Bycaught porpoises were usually healthy at the time of death and form a negative control group for investigations of infectious disease mortality. There was a statistically significant difference between the age structure of by-catches and animals dying of infectious diseases. More juveniles died of by-catch than adults and neonates, which contrasted with the greater number of adults that died of infectious diseases. Although inexperience may account for the greater by-catch related mortality within juveniles it is not readily apparent why more adults died of infectious disease compared to juveniles. It is possible that the longer term exposure of adults to a wider range of pathogens and contaminants may be involved. There were statistically significant seasonal patterns of by-catch and infectious disease mortality. By- catches occurred most commonly in January-June, whereas infectious disease mortality was most common within the winter period October-March. The colder water temperature probably accounts for the greater degree of infectious disease mortality within the winter, whereas the seasonal pattern of by-catch may relate more to distribution of porpoises and their prey, together with seasonal variation in fisheries effort. There were fewer cases of infectious disease mortality in Cornwall and Devon compared to other regions. This may be due to a seasonal increase in porpoise distribution around Cornwall and Devon during times when prey (and fisheries effort) are higher resulting in a seasonal pattern of porpoise by-catches between January-March which mirrors the situation with common dolphin strandings and by-catches within this region. By-caught porpoises have better nutritional status than those that died of infectious disease mortality and this difference was most pronounced during the summer months (April-September). This is not surprising since weight loss would be predicted in animals with chronic diseases resulting in a compromised health status. Furthermore, seasonal variation in water temperature may allow diseased animals to lose greater blubber in the summer when the water is warmer, whereas a minimum blubber layer must be maintained to avoid hypothermia.

4.2 Studies of the pathology and epidemiology of cetacean diseases

4.2.1 Investigations into the epidemiology of morbillivirus in cetaceans in UK waters

Two collaborative studies with Dr. Marie-Francoise Van Bressem (visiting researcher) and Dr. Tom Barrett at the Institute of Animal Health, Pirbright, have enabled 287 cetacean and 12 grey seal serum samples from animals stranded in England and Wales to be analysed for morbillivirus-specific antibodies. All serum samples were tested for the presence of DMV-specific antibodies in an indirect enzyme-linked immunosorbent assay (iELISA) on a coat of DMV antigen. In 1996 the first collaborative survey of 133 small cetaceans (10 species) stranded or bycaught along the coasts of the Western United Kingdom and Ireland (n=131), Holland (n=1) and Belgium (n=1) between 1989 and 1996 was conducted. These comprised 82 porpoises, 33 common dolphins, five striped dolphins, four white beaked dolphins, two bottlenose dolphins, two Risso’s dolphins and single samples from an Atlantic white-sided dolphin, a pilot whale, a killer whale and a Blainville`s beaked whale. DMV-specific antibodies were detected in the blood of eight harbour porpoises, two common dolphins, one long-finned pilot whale, one white-beaked dolphin stranded along the coasts of the UK between 1991-96. The seropositive pilot whale had the highest titre and was a juvenile whereas all the other seropositive individuals were sexually mature. The results of this study have been published within the scientific literature (Van Bressem et al. 1998). The second more recent study was conducted using serum samples from a further 154 cetaceans & 12 grey seals collected between 1996 and 1999. For the cetaceans, the same methodology as the previous study was used (Van Bressem et al. 1998). The seal sera was diluted 1:20 and screened on phocine distemper virus (PDV) and canine distemper virus (CDV) in the iELISA. The cetacean samples comprised 119 harbour porpoises, 20 common dolphins, 5 striped dolphins, 2 bottlenose dolphins, 2 minke whales, 2 white beaked dolphins, 1 pilot whale, 1 Risso’s dolphin, 1 Atlantic white-sided dolphin, 1 Sowerby’s beaked whale. The results will be published in the scientific literature (Van Bressem et al. submitted).

4.2.2 The pulmonary pathology of harbour porpoises (1990-1996)

Due to the importance of pulmonary disease as a cause of morbidity and mortality in stranded harbour porpoises, a review of the pulmonary pathological findings from postmortem examinations of 197 freshly dead to moderately decomposed harbour porpoises (Phocoena phocoena) stranded in England and Wales between October 1990 and December 1996 was undertaken (Jepson et al. 2000). Principal lesions, their aetiologies, and their frequencies are recorded in Table 4.1. In 135 individuals (69% of all cases) macroscopic nematode infections of the bronchial tract with Pseudalius inflexus and Torynurus convolutus, either singly or in combination, were recorded and 106 (54%) were also parasitised with P. inflexus within pulmonary blood vessels. All macroscopically parasitised individuals were adults or juveniles although 2 neonates had histological evidence of pulmonary nematode infection. Mild-severe subacute-chronic bronchitis and bronchiolitis (n=62), mild-severe chronic granulomatous interstitial pneumonia (n=113) and mild- severe vasculitis or thrombovasculitis of pulmonary blood vessels (n=34) were typical findings attributed to these nematode infections. Necro-purulent or purulent (broncho)pneumonias were attributed to secondary bacterial lung infections (n=35) or septicaemias associated with Streptococcus canis (n=7), Group B Salmonella spp. (n=2), E. coli (n=1) and Streptococcus lactis (n=1). Pulmonary lesions in 67 animals known or diagnosed to have been fatally entrapped in fishing gear were non-specific and included persistent foam in the pulmonary airways (n=45), diffuse pulmonary congestion (n=53), pulmonary oedema (n=50) and multifocal intra-alveolar haemorrhage (n=33). Acute fibrinous or chronic fibrous pleuritis (n=7), chronic necropurulent pneumonia associated with mycotic infections (n=7), traumatic lesions of the thorax and other parts of the body consistent with fatal attack from bottlenose dolphins (Tursiops truncatus) (n=4) and diffuse broncho-interstitial pneumonia associated with generalised morbillivirus infection (n=1) were also recorded. Table 4.1 Number and frequency of lesions recorded in the lungs of 197 harbour porpoises

CAUSE LESION No. individuals (% frequency)

parasitism bronchial tract 135 (69%) bronchitis/bronchiolitis 62 (31%) hyperplasia/metaplasia bronchial tract 28 (14%) chronic granulomatous interstitial pneumonia 113 (57%) Parasitic parasitism pulmonary blood vessel 106 (54%) proliferative arteritis/thrombovasculitis 34 (17%) pulmonary artery aneurysm 12 (6%) fatal pulmonary haemorrhage (probably parasitic 2 (1%) origin)

suppurative (broncho)pneumonia (+/- 46 (23%) abscessation) 11 (6%) Bacterial pneumonia/abscessation associated with 2 (1%) septicaemia 1 (<1%) bronchiectasis fibrinous pleuropneumonia

Mycotic chronic necropurulent pneumonia 7 (4%)

Viral broncho-interstitial pneumonia 1 (<1%)

Physical haemorrhagic pleural effusion 2 (1%) trauma pneumothorax 2 (1%)

multifocal acute alveolitis + proteinaceous alveolar 1 (<1%) Foreign body fluid 1 (<1%) aspirated sand 2 (1%) aspirated food material

Not determined acute-chronic pleuritis 6 (3%)

fine persistent froth in trachea and bronchi 100 (51%) pulmonary oedema 111 (56%) pulmonary congestion 136 (69%) Non-specific multifocal intra-alveolar haemorrhage 72 (37%) atelectasis 48 (24%) emphysema (alveolar) 32 (16%) anthracosis 5 (3%) 4.3 Relationships between contaminants and disease in harbour porpoises

Investigations into potential relationships between the exposure to persistent environmental contaminants and the health status of harbour porpoises have formed a important part of the research activity conducted under this and previous DETR-funded contracts held by the Institute of Zoology. Funding for analyses of contaminants was not included within this contract, but a long- standing collaboration with the Centre for Environment, Fisheries and Aquaculture Science (CEFAS) in Burnham-on-Crouch, Essex enabled analyses of organochlorines (polychlorinated biphenyls) and heavy metals to be conducted mainly on a selected number of harbour porpoises under the Ministry of Agriculture, Foods and Fisheries (MAFFs) own programme of environmental research. This collaborative research has resulted in a number of publications within the scientific literature during the period of this report. The principal findings of these investigations are summarised here.

4.3.1 Polychlorinated biphenyls and infectious disease mortality

Bioaccumulation of immunosuppressive organochlorines like polychlorinated biphenyls (PCBs) may pose a threat to the health and viability of cetacean populations. To investigate possible associations between chronic exposure to PCBs and infectious disease mortality in harbour porpoises (Phocoena phocoena) stranded in England and Wales, blubber concentrations of 25 individual chlorobiphenyl (CB) congeners in 34 healthy harbour porpoises that died due to physical trauma (mainly by-catch) were compared with CB concentrations in 33 animals that died due to infectious disease (Jepson et al. 1999). The infectious disease group had significantly greater total 25 CBs (S25CBs) concentrations than the physical trauma group (p<0.001). The mean S25CBs concentration in animals that died due to physical trauma was 13.6 mg kg-1 extractable lipid whereas the mean concentration in the infectious disease group was 31.1 mg kg-1 extractable lipid. The relationship between higher S25CBs and the infectious disease group was not confounded by age, sex, nutritional status, season, location or year of stranding. In addition, adult females had significantly lower S25CBs levels than adult males (p<0.05) due to maternal transfer of CBs to offspring. These findings are consistent with the hypothesis that chronic PCB exposure predisposes harbour porpoises in UK waters to infectious disease mortality, although further research (utilising a larger dataset) is required to test these associations more robustly.

4.3.2 Heavy metals and infectious disease mortality

We investigated whether long-term exposure to heavy metals, including immunosuppressive metals like mercury, is associated with infectious disease in a wild cetacean (Bennett et al. in press). Post mortem investigations on 86 harbour porpoises Phocoena phocoena found dead along the coasts of England and Wales revealed that 49 of the porpoises were healthy when they died as a consequence of physical trauma (most frequently entrapment in fishing gear). In contrast, 37 porpoises died of infectious diseases caused by parasitic, bacterial, fungal and viral pathogens (most frequently pneumonia caused by lungworm and bacterial infections). Statistical analyses showed that mean liver concentrations of Hg, Se, the He:Se molar ratio, and Zn were significantly higher in the porpoises that died of infectious disease compared to those that died from physical trauma. Liver concentrations of Pb, Cd, Cu and Cr did not differ between the two groups. Hg, Se, and the Hg:Se molar ratio were also positively correlated with age. The association between Zn concentration and disease status may result from Zn redistribution in response to infection. Further work is required to evaluate whether chronic exposure to Hg may have presented a toxic challenge to the porpoises that succumbed to infectious disease.

4.4 Other analyses of contaminants

4.4.1 Metals and organochlorines in other species

Blubber and liver samples from postmortem examinations conducted on a Blainville`s beaked whale (Mesoplodon densirostris) and a killer whale (Orcinus orca) were analysed by the CEFAS Laboratory, Burnham-on-Crouch, Essex for levels of organochlorines and heavy metals. The results of these analyses have been reported within the scientific literature (Law et al. 1997).

4.4.2 Butyltins

Samples of liver tissue collected under this contract from two Risso’s dolphins (Grampus griseus), two white beaked dolphins (Lagenorhynchus albirostris), two common dolphins (Delphinus delphis), two striped dolphins (Stenella coeruleoalba), and one specimen each of the long-finned pilot whale, white-sided dolphin, pygmy sperm whale, Sowerby’s beaked whale, Blainville`s beaked whale, northern bottlenose whale, fin whale and minke whale were analysed by CEFAS for concentrations of tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT). The results of this research, funded under MAFF`s own programme of environmental research, have recently been published (Law et al. 1999).

4.4.3 Radionuclides

During the period of this contract liver and muscle samples collected from postmortem examinations of common seals, grey seals and harbour porpoises that stranded in England and Wales (along with other samples from animals stranded in Scotland) have been analysed by the Nuclear Medicine Department, Southern General Hospital, Glasgow for levels of the radionuclides Cs137 and the naturally occurring K40. The results of this research, which was funded by the Greenpeace Environmental Trust, have recently been published (Watson et al. 1999). The study analysed levels of 134Cs, 137Cs, 238Pu, 239Pu, 240Pu in tissues from these and other individuals from around the UK coasts. Approximate radiation dose calculations indicated that the average dose from radiocaesium was less than 10% of the dose from the naturally occurring radioisotope of potassium, 40K (Watson et al. 1999).

4.5 Other ongoing research of pooled data in harbour porpoises

The following collaborative research projects on cetacean strandings are in progress at the Institute of Zoology.

4.5.1 Molecular genetic analysis of population structure of harbour porpoises in UK waters

The lack of precise data about harbour porpoise population structure in UK waters makes interpretation of disease data in stranded animals more difficult because we are not able to clearly define population units. We have therefore embarked upon a project to examine population structure by comparing microsatellite DNA sequences in archived skin samples from harbour porpoises examined during the course of this project. We have approximately 350 harbour porpoise skin samples archived of which 135 have had DNA extracted. Currently we are optimising the conditions for generating the specific microsatellite regions, before embarking on a screening process using a pre-determined suite of microsatellite DNA primers. We hope to identify enough genetic variation to be able to clearly define population structure for harbour porpoises in UK waters for the first time. This will not only help us perform epidemiological studies using pathological data, but also assist others in defining management units for this species. Molecular genetic variation will also be compared with phenotypic variation using traditional morphological traits (e.g. body length, skull measurements) to help characterise population structure in harbour porpoises.

4.5.2 Analysis of relationships between lungworm abundance and immunosuppressive contaminants in harbour porpoises

The potential relationships between health status and exposure to toxic contaminants in harbour porpoises is being explored in two new studies. We have begun counting lungworms through detailed and systematic dissections of harbour porpoise lungs. Heavy metal and organochlorine levels are currently being determined by CEFAS for the same individuals. An analysis of whether lung parasite abundance is correlated with tissue contaminant levels across these individuals will enable a more sensitive investigation of the possible causal link between immunosuppressive contaminants and health status in harbour porpoises. It is envisaged that over 60 individuals will be included within this study.

4.5.3 Analyses of the potential combined effect of organochlorines and heavy metals on the health status of harbour porpoises

Some authors have proposed that toxic organochlorines and heavy metals may have a combined effect that impairs immune function. The contaminant levels currently being determined by CEFAS together with previously collected data will permit a new combined analysis using both polychlorinated biphenyl (PCB) and heavy metals. This large database will allow us to test more robustly for possible associations between these compounds and the health and reproductive status of harbour porpoises in UK waters.

4.5.4 Reproductive system pathology

An analysis of the pathological and life history data collected from harbour porpoise postmortem examinations conducted in England and Wales between September 1990 and December 1999 is currently in progress. Data have been collated on a total of 370 harbour porpoises and will be analysed shortly. The results of the analyses will give a detailed insight into the reproductive health and fecundity of harbour porpoises in UK waters, and allow collaborative analyses of potential relationships between reproductive impairment/diseases and exposure to some types of persistent organic contaminants such as organochlorines and heavy metals. 5 Discussion and conclusions

During the period of this contract, 359 postmortem examinations of marine mammals stranded or by-caught in commercial fisheries within England and Wales were conducted, comprising 326 cetaceans of 14 different species, and 33 grey seals. By-catch was the most common cause of mortality in harbour porpoises and common dolphins throughout the period of this report. Excluding the 21 by-catches that were brought in from commercial fishing vessels, by-catch accounted for the cause of death of 64 (41%) of the 156 stranded harbour porpoises where a cause of death could be established. Of the 75 stranded common dolphins examined at postmortem during the period of this report, by-catch accounted for the cause of death of 32 which represents 54% of those for which a cause of death could be established. The cumulative total of harbour porpoise by-catches from the start of DETR-funded strandings research in the UK (September 1990) to the end of 1999 (excluding known by-catches retrieved from fishing vessels) is 119, which represents 39% of all established causes of death. The cumulative total of common dolphin by-catches from Sept 1990 to the end of 1999 is 118, which represents 71% of all established causes of death. The cutaneous lesions most commonly seen in by-caught harbour porpoises were consistent with entanglement in wide-meshed monofilament gillnet-type fishing gear. These type of lesions were much less prevalent within common dolphin by-catches. By-caught porpoises were frequently recorded in Wales, South-west England (Cornwall and Devon) and along the North Sea coastline from Northumberland to Humberside. In contrast, by-caught common dolphins were recorded in South-west England (Cornwall and Devon). By- catch was also markedly seasonal within Cornwall and Devon with more porpoises and common dolphins stranding between January to April. By-catch was also a greater proportion of the established causes of death for both common dolphins and porpoises than in porpoises from other regions. This seasonal pattern of high by-catch related mortality in both stranded common dolphins and harbour porpoises within Cornwall and Devon may be due to factors such as seasonal changes in the distribution of these species (and their prey) or changes in fisheries effort. A greater number of harbour porpoise by-catches were juveniles rather than adults or neonates. This may indicate that immature individuals are more vulnerable to by-catch related mortality, and that a degree of learning may be involved in the avoidance of entanglement in fishing gear. Common dolphins and harbour porpoises diagnosed as by-catches were also typically in good health and nutritional status. Physical trauma was diagnosed as the cause of death of 18 harbour porpoises, four common dolphins, two white beaked dolphins and one Risso’s dolphin during the period of this report. It is possible that some of these cases were additional by-catches. The nine stranded harbour porpoises with fatal traumatic lesions consistent with lethal attack by bottlenose dolphins all stranded within Cardigan Bay, West Wales where harbour porpoises have a sympatric distribution with a resident population of bottlenose dolphins. Juvenile porpoises were more vulnerable to this cause of mortality representing eight of the nine individuals affected. These cases represent the first evidence of fatal attack by bottlenose dolphins on harbour porpoises outside of Scottish waters. Infectious diseases were common causes of mortality in harbour porpoises, accounting for the death of 27 harbour porpoises during the period of this report. The most common causes of mortality due to infectious diseases in harbour porpoises were pneumonias (due to combinations of parasitic, bacterial and mycotic infections) and generalised bacterial infections. Infectious disease mortality was rarely recorded within strandings of other cetacean species. Animals that died of starvation comprised 16 harbour porpoises (including 9 neonates), two common dolphins (including one calf), two white beaked dolphins, two minke whales (both calves), one striped dolphin and one killer whale. Maternal separation was considered the most probable cause of starvation in maternally dependent individuals. The pathophysiological effects of live stranding (as opposed to significant underlying disease) was considered the cause of death for 17 otherwise healthy harbour porpoises, together with 12 common dolphins, three striped dolphins, three white beaked dolphins, and single strandings of a pigmy sperm whale, a pilot whale, a Sowerby’s beaked whale, and a northern bottlenose whale. Of the 17 fatally live-stranded harbour porpoises, more stranded on the east coast of England than on either the south-west coast of England (Cornwall and Devon) or Wales. This may be due to differences in the topography between the east coast (with its shallower sandbanks and longer inter- tidal reaches) being more difficult to safely navigate than the shorter and rockier coastline of the south-west of England and Wales. No cases of morbillivirus were diagnosed in any species during the period of this contract report. The results of the serological studies for morbillivirus-specific antibodies provided an interesting insight into the prevalence and epidemiology of morbillivirus in cetaceans in UK waters. Apart from the seropositive juvenile pilot whale, all seropositive cetaceans were adults in which morbillivirus-specific antibodies could be the consequence of an infection contracted during 1988- 1990 when the last cetacean morbillivirus epizootics were diagnosed in cetaceans in the NE Atlantic. The apparent low proportion of seropositives and the absence of convincing evidence for recent infection in these species may indicate that they are not involved in persistence of morbillivirus in UK waters but merely accidental hosts. The strongly seropositive juvenile pilot whale (in this study) that stranded in 1996, together with the diagnosis of morbillivirus infection in a fin whale stranded in Belgium in 1997, provides evidence for the recent circulation of cetacean morbillivirus in the NE Atlantic. Although no mass mortalities have been observed in cetaceans of the NE Atlantic or Mediterranean Sea since 1992, the likely persistence of the virus in this ocean province could represent a continuous threat to populations which do not benefit from herd immunity, by providing the source for initiation of morbillivirus epizootics. Two studies investigating potential relationships between the health status of harbour porpoises and their exposure to polychlorinated biphenyls (PCBs) and heavy metals were conducted during the period of this report. The first study (of 86 individuals) established a statistically significant association between elevated levels of both Hg and Hg:Se ratios in the livers of animals dying of infectious diseases (when compared to health animals dying of physical trauma). The second study concentrations (of 67 individuals) demonstrated a similarly significant association between elevated blubber PCB and mortality due to infectious disease. The findings of both studies are suggestive of a causal relationship between chronic PCB and Hg exposure and infectious disease mortality. However, the datasets in these studies were relatively small and data for some potentially confounding variables such as age were incomplete. A larger and more complete dataset would be required to test these statistical associations more rigorously. The possibility of additive or synergistic effects between these (and other) groups of contaminants also must be considered. Future studies will seek to utilise larger datasets in order to test more robustly for potential relationships between both organochlorine and heavy metal levels and the health status of harbour porpoises. However, the associations reported here clearly demonstrate the importance of continued monitoring for the possible effects of exposure to persistent environmental contaminants on the health status of marine mammals in UK waters, both in the context of their population viability and also as potential biomarkers of contaminant-related damage to marine ecosystems. There has been a low prevalence of neoplasia recorded in cetaceans both during the period of this report and since the beginning of strandings research in 1990. Neoplasia is an important biomarker for the potential effects of exposure to carcinogenic environmental compounds such as radionuclides and some polycyclic aromatic hydrocarbons such as benzo-a-pyrene. Tissue samples collected from harbour porpoises and common and grey seals stranded in England and Wales and held within the Institute of Zoology tissue archive were submitted to a study funded by the Greenpeace Environmental Trust and conducted by the Nuclear Medicine Department of Southern General Hospital, Glasgow. The study analysed levels of 134Cs, 137Cs, 238Pu, 239Pu, 240Pu in tissues from these and other individuals from around the UK coasts. Approximate radiation dose calculations indicated that the average dose from radiocaesium was less than 10% of the dose from the naturally occurring radioisotope of potassium, 40K (Watson et al. 1999). Therefore, the low prevalence of neoplasia recorded in stranded cetaceans throughout the period of DETR-funded strandings research is encouraging, particularly when compared to other regions such as the Gulf of St Lawrence, Canada, where a high prevalence of neoplasia has been recorded within a resident population of belugas (Delphinapterus leucas) and linked to exposure to environmental carcinogens.

6 Recommendations for future research

Future research should include continued monitoring of cetacean mortality using standard procedures on a European scale, investigations into interactions between fisheries and cetacean populations, genetic studies of population structure, and investigations into the importance of toxic contaminants as causes of immunosuppression and endocrine disruption in cetaceans. 7 List of publications resulting from this project 1995-2000

Baker, J.R., Jepson, P.D., Simpson, V.R. & Kuiken, T. (1998) Pathology of grey seals (Halichoerus grypus) found dead on the coasts of England, Wales and the Isle of Man. Veterinary Record 142, 595-601.

Bennett, P.M., Jepson, P.D., Law, R.J., Jones, B.R., Kuiken, T., Baker, J.R., Rogan, E. & Kirkwood, J.K. (in press). Exposure to toxic metals and infectious disease mortality in harbour porpoises from England and Wales. Environmental Pollution, in press.

Gibson, D., Harris, E.A., Bray, R.A., Jepson, P.D., Kuiken, T., Baker, J.R. and Simpson, V.R. (1998) A survey of the helminth parasites of cetaceans stranded on the coast of England and Wales during the period 1990-1994. J. Zool., Lond. 244, 563-574.

Jepson, P.D. & Baker, J.R. (1998) Bottlenose dolphins (Tursiops truncatus) as a possible cause of acute traumatic injuries in porpoises (Phocoena phocoena). Veterinary Record 143, 614-615.

Jepson, P.D., Baker, J.R, Kuiken, T., Simpson, V.R., Kennedy, S. and Bennett, P.M. (2000) Pulmonary pathology of harbour porpoises (Phocoena phocoena) stranded in England and Wales between 1990 and 1996. Veterinary Record 146, 721-728.

Jepson, P.D., Bennett, P.M., Allchin, C.R., Law, R.J., Kuiken, T., Baker, J.R., Rogan, E., & Kirkwood, J.K. (1999) Investigating potential associations between chronic exposure to polychlorinated biphenyls and infectious disease mortality in harbour porpoises from England and Wales. The Science of the Total Environment 243/244, 339-348.

Jepson, P.D., Brew, S., Macmillan, A.P., Baker, J.R., Barnett, J., Kirkwood, J.K., Kuiken, T., Robinson, I.R. & Simpson, V.R. (1997) Antibodies to Brucella in marine mammals around the coast of England and Wales. Veterinary Record 141: 513-515

Karakosta, C.V., Jepson, P.D., Ohira, H., Moore, A., Bennett, P.M. and Holt, W.V. (1999) Testicular and ovarian development in the harbour porpoise (phocoena phocoena). Journal of Zoology 111, 111-121.

Kirkwood, J.K., Bennett, P.M., Jepson, P.D., Kuiken, T., Simpson, V.R. and Baker, J.R. (1997) Entanglement in fishing gear and other causes of death in cetaceans stranded on the coasts of England and Wales. Veterinary Record 141, 94-98.

Kuiken, T. (1996) Review of the criteria for the diagnosis of by-catch in cetaceans. In: T. Kuiken (Editor) Proceedings of the second ECS workshop on cetacean pathology: Diagnosis of by- catch in cetaceans, Montpellier, France, 2 March, 1994. European Cetacean Society Newsletter, no 26, special issue. pp 38-43.

Law, R.J., Allchin, C.R., Jones, B.R., Jepson, P.D., Baker, J.R. & Spurrier, C.J.H. (1997) Metals and organochlorines in tissues of a Blainville`s beaked whale (Mesoplodon densirostris) and a killer whale (Orcinus orca) stranded in the United Kingdom. Marine Pollution Bulletin 34: 208-212

Law, R.J., Blake, S.J., Spurrier, C.J.H. (1999) Butyltin compounds in liver tissues of pelagic cetaceans stranded on the coasts of England and Wales. Marine Pollution Bulletin 38: 1258-1261.

Kirkwood, J.K, Bennett, P.M., Jepson, P.D., Kuiken, T., Simpson, V.R. & Baker, J.R. (1997) Entanglement in fishing gear and other causes of death in cetaceans stranded on the coasts of England and Wales. Veterinary Record 141: 94-98

Rogan, E., Baker, J.R., Jepson, P.D., Berrow, S. & Kiely, O. (1997) A mass stranding of white- sided dolphins (Lagenorhynchus acutus) in Ireland: biological and pathological studies. Journal of Zoology 242: 217-227.

Van Bressem, M.F., Jepson, P.D. & Barrett, T. (1998) Further insight on the epidemiology of cetacean morbillivirus in the northeastern Atlantic. Marine Mammal Science 14(3): 605-613

Watson, W.S., Sumner, D.J., Baker, J.R., Kennedy, S., Reid, R., Robinson, I. (1999) Radionuclides in seals and porpoises in the coastal waters around the UK. Science of the Total Environment 234:1-13. Conference Abstracts

Jepson, P.D., and Robinson, I.R. (1995) A rare congenital heart defect in a harbour porpoise (Phocoena phocoena) calf from Cardigan Bay, Wales. Proceedings of the ninth Annual Conference of the European Cetacean Society, 9-11 February 1995, Lugano.

Jepson, P.D., Brew, S., Macmillan, A.P., Baker, J.R., Barnett, J., Kirkwood, J.K., Kuiken, T., Robinson, I.R. & Simpson, V.R. (1995) Antibodies to Brucella in marine mammals around the coast of England and Wales. Proceedings of the eleventh Biennial Conference on the Biology of Marine Mammals, Orlando, Florida, 14-18 December 1995.

Jepson, P.D., Brew, S., Macmillan, A.P., Baker, J.R., Barnett, J., Kirkwood, J.K., Kuiken, T., Robinson, I.R. & Simpson, V.R. (1996) Antibodies to Brucella in marine mammals around the coast of England and Wales. Proceedings of the tenth Annual Conference of the European Cetacean Society, Lisbon, Portugal, 11-13 March 1996.

Jepson, P.D., Bennett, P.M., Kirkwood, J.K., Kuiken, T., Simpson, V.R. and Baker, J.R. (1997) Bycatch and other causes of mortality in cetaceans stranded on the coasts of England and Wales 1990-1996. Proceedings of the eleventh annual conference of the European Cetacean Society, Stralsund, Germany, 10-12 March 1997.

Jepson, P.D., Baker, J.R., Kuiken, T., Simpson, V.R. and Bennett, P.M. (1998) Reproductive system pathology of cetaceans stranded in England and Wales. Proceedings of the Reproductive Workshop Report of the World Marine Mammal Science Conference, Monaco, 17-18 January 1998 (also to be published in European Research on Cetaceans 12)

Jepson, P.D., Bennett, P.M., Allchin, C.R., Baker, J.R., Kuiken, T., Rogan, E., Lockyer, C., Law, R.J., Walton, M.J. and Kirkwood, J.K. (1998) Chronic PCB exposure is associated with infectious disease mortality in harbour porpoises stranded in England and Wales 1990-1996. Proceedings of the first World Marine Mammal Science Conference, Monaco, 20-24 January 1998.

Bennett, P.M., Jepson, P.D., Law, R.J., Jones, B.R., Kuiken, T., Baker, J.R., Rogan, E. & Kirkwood, J.K. (1999) Exposure to toxic metals and infectious disease mortality in harbour porpoises from England and Wales. Proceedings of the thirteenth annual conference of the European Cetacean Society, Valencia, Spain 5-8 April 1999.

Jepson, P.D., Baker, J.R., Kuiken, T., Simpson, V.R., Kennedy, S. & Bennett, P.M. (1999) Pulmonary pathology of harbour porpoises stranded in England and Wales between 1990 and 1996. Proceedings of the thirteenth Biennial Conference on the Biology of Marine Mammals, Maui, Hawaii, 28 November - 3 December 1999.