The Cardiff University Otter Project relies on reports of carcasses by members of the public, and organisations such as the Environment Agency, Countryside Council for Wales, UK Wildlife Trusts, the police and local authorities.

In the event of finding a dead otter, please telephone 07808 506506 (Environment Agency) and ask for your nearest conservation / biodiversity officer. Other schemes collect a variety of wildlife species for monitoring purposes. For information on other schemes see WILDCOMS.

We are currently seeking funding to ensure continuity of the Otter Project; if you are interested in helping fund our work please contact the Project Manager.

CONTENTS

Website last updated 10th September 2009

BACKGROUND

Although once widespread throughout Europe, the Eurasian otter underwent a dramatic decline in 20th century, to the point where the species became rare or extinct across much of its former range (Chanin 2003). In the UK it is thought that the decline began in the mid 1950s, and continued until at least the mid 1970s. The otter population was eliminated from much of England, with remaining populations restricted to parts of N Ireland, Wales, SW England and Scotland (Jones and Jones 2004).

	A range of evidence suggests that these declines were related to the use of endocrine disrupting chemicals (EDCs) including organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs) (e.g. Jefferies and Hanson 2000, Roos et al 2001, Simpson et al 2000 ). Many EDCs biomagnify and bioaccumulate in the aquatic food chain. Fish-eating aquatic mammals such as otters may therefore be particularly vulnerable to the impact of EDCs, due to their position at the top of the food chain, their dependence on aquatic food sources, and their habitat being located in areas influenced by industry and agriculture. EDCs have been shown to impair reproductive function of mustelids, and this has been suggested as the major reason behind the Eurasian otter’s decline (Fossi and Marsili 2003).
Although otter populations are still recognised by the IUCN as ‘near-threatened’, a combination of protective legislation and improvements in water quality have led to a gradual recovery, through both range expansion and increased abundance. Otter populations are now expanding over much of Europe, including the UK. Distribution in England and Wales has increased and it has been suggested that the decline in levels of OCs and PCBs since legislation restricting or banning their use may have contributed to population recovery. This may reflect increasing vitamin A levels, which Simpson et al (2000) found to be correlated with both declining PCBs/OCs and with increasing populations. Increasing otter numbers may result in conflict between fisheries owners and otters; for information about protecting still-water fisheries see here.
In northern Europe the otter is the dominant predator of riverine food chains, and as such, levels of pollutants in otter tissues can be a useful indicator of pollution in the environment in which it feeds.

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THE PROJECT

Since 1992, the Environment Agency (EA) has funded researchers to conduct post-mortem examinations of otters found dead in the UK. Until recently, otters from EA management regions in the south were sent to Vic Simpson at the Wildlife VIC in Cornwall, and otters from the remainder of England and Wales were sent to Cardiff University Otter Project (CUOP) (Fig 1). Since July 2007 CUOP have taken otters from the whole of England and Wales, and have so far examined over a thousand otters from all over the UK, predominantly killed in road traffic accidents. Otters in England and Wales are nocturnal, elusive and trap-shy; direct observations are therefore difficult. Most research is based on indirect observation such as surveys of spraint (faeces). Information gained from research using otters found dead therefore forms an important contribution to our knowledge. While otter deaths on roads are clearly undesirable, opportunistic use of such events provides the chance to take observations, measurements, biological specimens or samples that can be of great benefit to ecological research. In addition to this, the location of mortality incidents has been used to put in place mitigation on roads to reduce the number of future casualties.		Fig 1. Otters received between 1992 and June 2008
			Otters received by CUOP
			Otters received by Vic Simpson at the Wildlife VIC
Until 2004, the CUOP was managed by Dr A Bradshaw. Results of research carried out until 2000 are summarised in Bradshaw (1999) and in Bradshaw & Slater (2002); this report is available from the Environment Agency (R & D Technical Report W1-019/TR). Additional publications were made regarding chemical signalling via scent glands (Bradshaw et al 2001), and monitoring the use of otter holts using hair analysis (Cowell et al, 2001).

Since 2004, the CUOP has been managed by Dr E Chadwick. Results of research carried out between 2000 and 2003 were analysed in conjunction with data from 1992-2000, forming a report to the Environment Agency (Chadwick 2007). In addition, a number of new collaborations have been established with other universities and organisations, including Swansea University (diet, parasites), the Wildlife VIC in Cornwall (lead levels, genetics) University of Exeter (PBDEs), NERC stable isotope facility at East Kilbride (stable isotope research) and the National Museums of Scotland (cleaning and archiving of bony material) to carry out a wide range of research.

Recent reports relating to otter post mortem work at Cardiff University and by Vic Simpson at the Wildlife VIC are available on the Environment Agency website, or can be accessed here (Simpson, 2007) or here (Chadwick, 2007).

Details of our current post-mortem protocol can be accessed here.

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LICENSING

Under current EU legislation it is necessary to have a licence to possess or transport dead specimens of animal species listed on Annex IV of the Habitats Directive. CUOP holds a general licence for Wales and England which covers any individual involved in collecting, storing, or transporting otter specimens for the project. Click to see a copy of the general licence for England or Wales.

CURRENT RESEARCH

Landscape genetics. A PhD study began in October 2005 using otter specific microsatellite primers to analyse muscle samples. The project has several aims, including examination of sub-structuring within otter populations, determining source populations involved in the re-colonisation of England, and assessment of the contribution made by reintroduced animals to population recovery. In addition to samples from the CUOP, collaboration has been established with V Simpson at the Wildlife VIC in Cornwall, to obtain samples from southern England. This work is being carried out by PhD student Geoff Hobbs (HobbsGI@cardiff.ac.uk), supervised by Prof M Bruford, Dr F Slater and Dr E Chadwick at Cardiff University. So far, the research has been highly successful and has found some sub-structuring within Welsh and English populations. Preliminary results were presented at the European Otter Workshop in Italy, and are published in Hobbs et al 2006. Work assessing genetic diversity and struct using mitochondrial DNA has been accepted for publication (Stanton et al accepted for Conservation Genetics publication 2009).

	Diet. A collaborative project has been established between Cardiff and Swansea Universities to examine diet. Most work looking at otter diet uses spraint (otter faeces), but there are various problems with this – for example, some food items are passed in numerous separate spraint, rendering quantification difficult. As part of a PhD study, Gareth Parry is looking at prey remains in the stomach and gastrointestinal tract, supervised by Dr D Forman at Swansea University.
While only a small number have been examined thus far, preliminary analyses have identified eel, salmonid, stickleback and a variety of marine species. In addition, avian prey includes species such as mallard, coot, pied wagtail and crow, and mammalian prey includes brown rat, bank vole and rabbit. In one instance domestic refuse (including a rubber balloon) was recovered, from an emaciated juvenile.
Ectoparasites. Most previous studies have assumed that ectoparasites are lost soon after death of the host, so few researchers have searched thoroughly for ectoparasites. In a further collaboration with Dr D Forman, we have identified several species of ticks – predominantly Ixodes trianguliceps and I. ricinus, and also several hedgehog ticks (I. hexagonus). Infestation rates vary widely between animals; future analysis should enable us to determine seasonal and spatial patterns.

Endoparasites. During examination of the digestive tract for prey remains, it is also possible to remove endo-parasites for identification. Suprisingly few adult endo-parasites have been recovered from the gastro-intestinal tract of the otters sampled to date. This is very simlar to data obtained from otters in Denmark, where endoparasites were found in less than 4% of animals examined (Madsen and Gaardmand 2000). The majority of parasites recovered are helminths (of both marine and freshwater origin), predominately from the small intestine. In addition, animals are screened for Angiostrongylus vasorum (canine heart worm), a parasite capable of causing severe respiratory and heart problems to dogs and occasionally members of the mustelid family; all findings so far are negative.

Pseudamphistomum truncatum: In light of the recent finding of the fluke P. truncatum (not previously recorded in Britain) in the gall bladders of otters and mink from Somerset (Simpson et al. 2005), gall bladders are now also retained for further examination. We have now searched 273 gall bladders to date and have found flukes present in 11.7%.

Metorchis albidus: Following the discovery of P. truncatum, a second digenean trematode has been identified. This species is not native to the UK. Metorchis albidus was found in 6.6% of otter gall bladders examined, and appears to be well established in Suffolk, Norfolk and north Essex.

The distribution of the two parasites is discussed in a recent publication (Sherrard-Smith et al., 2009) and the distribution, life history and pathogenicity of P. truncatum is discussed by Simpson et al (2009).

Further research is being undertaken by PhD student Eleanor Sherrard-Smith (sherrardsmithe@cardiff.ac.uk) to assess routes of spread, describe the life cycle of both parasites in UK water systems, and to develop a DNA screening method that can be applied to spraint. This PhD is generously funded by NERC and the Somerset Otter Group.

Toxoplasma gondi is a common parasite, of which the primary host is the domestic cat, which causes the infection known as Toxoplasmosis. T. gondii is a major cause of death of the southern sea otter Enhydra lutris nereis (Conrad et al. 2005) and is globally widespread, but levels in Eurasian otters have not been assessed until now. In a further collaboration with D Forman, blood samples are screened for T. gondii. So far, we have found Toxoplasmosis in ~30% of males tested (n = 72), and nearly 60% of females (n = 45). The implications of this are not yet known, but it does not appear to affect Eurasian otters as severely as the southern sea otter, and is not implicated as the cause of death in any of the animals found.

Lead levels. In view of changes in legislative control of lead in car fuel, collaboration was established with V Simpson at the Wildlife VIC in Cornwall to examine lead levels in otter bone. We found a dramatic decline, consistent with the reduction in atmospheric lead. This research was undertaken by final year student Abigail Nicholls, supervised by E Chadwick and F Slater and was presented at the IXth International Mammalogical congress in Japan (Chadwick et al. 2005) (publication in prep).

Cranial morphometrics. Examination of the skull has revealed sexual dimorphism in size and shape, which is probably associated with differences in feeding – for example, even when allowing for differences in skull size, males have significantly longer canines than females. Preliminary research was undertaken by final year student Joanna Bishop at Cardiff University, supervised by E Chadwick and F Slater. Further research has been undertaken in collaboration with D Forman, Swansea University (publication in prep). Skulls were cleaned by the National Museums of Scotland (NMS), and will be held in their archive (A Kitchener, principal curator of mammals and birds).

Age. During analysis of cranial morphometrics (above) the degree of closure of cranial sutures was also examined. It was noted that in some cases, animals classified as adults on the basis of body size had sutures that were not entirely closed, and were therefore younger than previously assumed. Re-examination of all skulls to assess cranial suture closure has been completed; this will be examined in relation to other indicators of age. These include baculum (penis bone) size, evidence of reproductive activity, and overall size of the animal. ‘Cementum analysis’ uses rings in teeth to assess age, and has been arranged at Matson’s laboratory in the USA; it is hoped that comparison of these various indicators will help clarify age classifications. This will be useful with regard to assessing population structures, and in conjunction with bioaccumulation of chemical pollutants. Baculae are currently being cleaned at the NMS, and will be held in their archive following measurement.

PBDEs (polybrominated diphenyl ethers) were widely used as fire retardants until European legislation banning their use in 2003. In collaboration with the University of Exeter, analyses are being undertaken to look at presence of PBDEs in otter livers, sourced from both the CUOP and Wildlife VIC. Preliminary results suggest that levels found were similar to the high levels found within marine mammals. The research is being undertaken by PhD student Angela Pountney, supervised by Dr J Stevens and Prof Charles Tyler.

PCBs (polychlorinated biphenyls) and OCs (organochlorine pesticides) were thought to be a major contributor to the decline of otter populations throughout Europe. Analysis of PCB and OC levels in otter livers has been completed for all samples collected 1992-2003; results of this analysis are presented by Chadwick (2006). Some regional trends were apparent, with higher levels of PCBs in the North, and higher levels of OCs in the Midlands. Comparisons with previous work (Jefferies and Hanson 2000) suggest steep declines since the 1960s. Levels in males were higher than in females, and showed clear evidence of a positive correlation with body size (assumed to indicate bioaccumulation with age). In females, there was evidence for initial accumulation, followed by decreases with increasing size, probably due to shedding of their pollutant burden during reproduction.

Marine derived nutrients (MDNs). Marine food webs tend to be enriched in the heavier stable isotopes of carbon and nitrogen compared to freshwater food webs. Carbon and nitrogen from food are incorporated into the body tissues of consumers, and their stable isotopes can be used to indicate the contribution of marine-derived nutrients (MDNs) to diet (Rubenstein and Hobson 2004). MDNs can be translocated into freshwater systems by vectors such as anadromous fish, which may then be predated by other consumers. MDN contributions may be vital to freshwater ecosystem functioning, but the distribution of MDNs in European freshwater systems has not been widely investigated. The position of the otter as the top predator in N European river systems allows the stable isotope signature of their tissues to be used as an index of the MDN contribution to ecosystems in which they feed. Analyses of otter tissues and spraint can also contribute valuable information regarding the diet and behaviour of this cryptic species. A pilot study carried out in collaboration with the NERC Life Sciences Mass Spectrometry Facility (LSMSF) has generated promising results; and further analysis is underway to examine nutrient cycling within welsh catchments using otter muscle and bone.

Scent Analysis. A PhD beginning April 2008 (Eleanor Kean: KeanEF@cardiff.ac.uk) aims to assess variation in the chemical profile of material from otter scent glands. Variation in the chemical constituents of scent will be analysed to test for differences between individuals, and between groups (e.g. males and females, adults vs. sub-adults etc.). It is hoped that this can be used as a monitoring tool, to identify individuals from the scent signature in field collected spraint. Solid phase micro-extraction (SPME) and gas chromatography-mass spectrometry (GC-MS) are used to extract and analyse the volatiles associated with otter scent. We are very grateful to the following centres, with captive Eurasian otters, who have kindly provided much needed spraint samples from known individuals to assist this work: The NewForest Otter, Owl and Wildlife Park; Dartmoor Otter Sanctuary, Buckfastleigh; and The British Wildlife Centre. We would like to thank the Environment Agency and RWE npower for their financial support. GATI

MITIGATION

The death of otters on roads can have a serious impact on populations in some areas, particularly where population densities are low or where danger-spots impact on breeding females. Otters can travel several miles in a night, and often cross roads where rivers are culverted or bridged. In many cases mortality can be limited or prevented by provision of simple mitigation measures.
	Figure 2: Dry culvert on A470, Wales (Photograph provided by Jean Matthews)
Suitable mitigation measures are described in reports by Grogan (2001) and by Liles and Colley (2000, 2001), and include the installation of dry culverts (e.g. Figure 2) or bolt on ledges (e.g. Figure 3), in combination with fencing to guide otters to the safe passage point.
	Figure 3: Otter ledge at Pont Dolau in Wales (photograph provided by Geoff Liles)
	To see a video clip of an otter using a ledge on the A497 near Pwllheli, click the 'play' button (lower left).   (Video clip provided by the Environment Team, Gwynedd Consultancy [Miss Alex Jones, Group Environment Officer]).

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REFERENCES

Bradshaw AV (1999) Aspects of otter Lutra lutra mortality in England and Wales. PhD thesis, Cardiff University.

Bradshaw AV, Beckman M, Stevens R, Slater FM (2001) Anal scent gland secretion of the European otter (Lutra lutra). In: Chemical Signals in Vertebrates. Kluwer Academic, New York.

Bradshaw AV, Slater FM (2002) A postmortem study of otters (Lutra lutra) in England and Wales. Environment Agency R&D Technical Report W1-019/TR.

Chadwick EA, Simpson VR, Slater FM, Nicholls AE (2005) Heavy metals in otters Lutra lutra: Dramatic decline in lead in the period 1992-2004. Poster presented at the IXth International Mammalogical Congress, 1st-5th August 2005, Sapporo, Japan.

Chadwick EA (2006) A post mortem study of otters found dead in England and Wales between 1992 and 2003. Environment Agency R & D Technical Report W1-084.

Chanin P (2003) Ecology of the European otter. English Nature, Peterborough.

Conrad PA, Miller MA, Kreuder C, James ER, Mazet J, Dabritz H, Jessup DA, Gulland F, Grigg ME (2005) Transmission of Toxoplasma: Clues from the study of sea otters as sentinels of Toxoplasma gondii flow into the marine environment. International Journal for Parasitology 35 (11-12) 1155-1168.

Cowell D, Thomas G, Liles G, Bradshaw A, Midgley L, Slater F (2001) Monitoring the use of artificial log pile otter holts using hair analysis from bedding. IUCN Otter Specialist Bulletin 18 (1) 6-10.

Fossi MC, Marsili L (2003) Effects of endocrine disruptors in aquatic mammals. Pure and Applied Chemistry 75(11-12) 2235-2247.

Grogan AL, Philcox CK, MacDonald DW (2001) Nature Conservation and roads: Advice in relation to otters. Wildlife Conservation Research Unit, Oxford.

Hobbs G, Chadwick EA, Slater FM, Bruford M (2006) Landscape genetics applied to a recovering otter (Lutra lutra) population in the UK: preliminary results and potential methodologies. Hystrix 17(1) in press.

Jefferies DJ, Hanson HM (2000) The role of dieldrin in the decline of the otter (Lutra lutra) in Britain: the analytical data. In Conroy, J W H, Yoxon, P and Gutleb, A C (Eds.), Proceedings of the First Otter Toxicology Conference, Skye, Sept 2000 (pp. 95-143): International Otter Survival Fund, Broadford, Scotland.

Jones T, Jones D (2004) Otter survey of Wales 2002. Environment Agency Report.

Liles G, Colley R (2000) Otter Lutra lutra road deaths in Wales. Identification of blackspots and establishment of mitigation measures. Report for the Environment Agency Wales, Welsh Water, and the Wildlife Trusts Otters and Rivers Project.

Liles G, Colley R (2001) Otter (Lutra lutra) road mortalities: a procedure for the implementation of mitigation measures. A report for the Environment Agency Wales.

Madsen AB, Gaardmand B (2000) Otter Lutra lutra monitoring in Denmark based on spraint surveys, collected carcasses and reported observations. Lutra 43 29-38.

Roos A, Greyerz E, Olsson M, Sandegren F (2001) The otter (Lutra lutra) in Sweden - population trends in relation to Sigma DDT and total PCB concentrations during 1968-99. Environmental Pollution 111 (3) 457-469.

Rubenstein DR , Hobson KA (2004) From birds to butterflies: animal movement patterns and stable isotopes. Trends in Ecology and Evolution 19(5) 256-263.

Sherrard-Smith E, Cable J, Chadwick EA (2009) Distribution of Eurasian otter biliary parasites, Pseudamphistomum truncatum and Metorchis albidus (Family Opisthorchiidae), in England and Wales. Parasitology 136 1015-1022.

Simpson VR, Bain MS, Brown BF, Lacey RF (2000) A long-term study of vitamin A and polychlorinated hydrocarbon levels in otters (Lutra lutra) in south west England. Environmental Pollution 110 (2) 267-275.

Simpson VR, Gibbons LM, Khalil LF, Williams JLR (2005) Cholecystitis in otters (Lutra lutra) and mink (Mustela vison) caused by the fluke Pseudamphistomum truncatum. Veterinary Record 157(2) 49-52.

Simpson VR, Tomlinson AJ, Molenaar FM (2009) Prevalence, distribution and pathological significance of the bile fluke Pseudamphistomum truncatum in Eurasian otters (Lutra lutra) in Great Britain. Veterinary Record 164 397-401.

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