DEAD OTTERS inSOMERSET · and Metorchis albidus (Family Opisthorchiidae), in England and Wales. A...
Transcript of DEAD OTTERS inSOMERSET · and Metorchis albidus (Family Opisthorchiidae), in England and Wales. A...
Somerset, UK October 2018
Somerset Otter Group dead otter summary www.somersetottergroup.org.uk 1
DEAD OTTERS in SOMERSETSomerset Otter Group, An update and summary of dead otter records.
© Crown Copyright
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It is sad to record otter deaths and sad that Somerset has so manyrecords. But the information obtained from both recording andrecovering otter bodies provide an exceptional opportunity to learnmuch more about this iconic species. And where possible installmitigation measures to prevent further deaths.
The fact we have so many records is not an indication of anextraordinary number of deaths but an example of huge effortdedicated over decades by a group of people. Initially enthused byJames Williams, and suitably carried on, as he handed over the baton.
Thank you to everyone who has assisted in the reporting, collecting,recording, storing, transferring or autopsying of dead otters inSomerset.
Dead Otter records in Somerset, 1999 to 2017
Records
The Somerset Otter Group hasaccess to extraordinary otterdata, including historical deadotter records courtesy of theJames Williams Archive.
Partners------------------------------------The Somerset Otter Group workswith the Environment Agency (EA),who initially funded autopsiesdone by Vic Simpson in Cornwall.James Williams persuaded them toextend this service to otters fromSomerset. In 2007 this fundingtemporarily changed to the CardiffUniversity Otter Project, wheresince 2007 Somerset has sent itsdead otters.
We coordinate with the EA in thecompletion and numbering ofrecords and for the last 3 years thegroup has taken over theresponsibility for the transfer ofbodies to Cardiff University.
It is important the group isinformed of any otters likely to beplaced in the freezers, if we don’tknow about them we can’t processthem. See our website for currentcontact details for Jo Pearse.
Secret World kindly house a freezerpurchased by the Somerset OtterGroup. West Hatch RSPCA kindlyprovide a freezer for the samepurpose, both assist in booking inthe otters. Rob Williams houses atransit freezer in Wellington.
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Cardiff University OtterProject
Taxidermy
We receive anecdotal evidenceof otters going for taxidermy,but we are losing valuableinformation. There are a fewlegitimate reasons fortaxidermy, so if an otter is takenplease ensure that it is alsoreported to the Somerset OtterGroup or to the EnvironmentAgency. Cardiff University otterproject can advise on whatunwanted parts can be retainedfor them and we can organisetransfer of those parts. At thevery least we would like toknow the details of where andwhen the otter was found.
The Project runs a long termenvironmental surveillancescheme, using otters founddead to investigatecontaminants, disease, andpopulation biology across theUK.
Visit their website;www.cardiff.ac.uk/otter-project
Or follow them on
Licence
In keeping with the protectedstatus of the otter a licence isrequired to handle any part ofa dead otter. The SomersetOtter Group operates underthe licence held by the CardiffUniversity Otter Project incollecting the dead otters.
Summary of dead otters in 2017
We have recently received all the autopsy reports from CardiffUniversity Otter Project for the 2017 otters. 33 deaths wererecorded and 22 were collected and sent for autopsy. 13 malesand 9 females, one of which was unfortunately lactating whichsignals the additional loss of her cubs, not included in the totals.
Five of the 33 were sub adults, two male, two female and oneunknown. One female had a very small heart and possibly diedthrough a heart defect.
Two had thickened gall bladders indicating possible flukeinfection; an adult male on the River Parrett near Langport and anadult female on minor rhynes of the River Axe (North), nearWeston Super Mare.
Three were confirmed negative for fluke; one on the Haddeo,River Exe catchment, had signs of a fibrous gall bladder and wasoutside the area known for fluke, but was confirmed by CardiffUniversity as negative for fluke.
Several deaths reported in the same area on the River Parrettresulted in mitigation action being raised with the EnvironmentAgency, the results of that work awaits.
Mitigation
Recording otter deaths highlights blackspots and enablesmitigations such as; reflectors, ledges under bridges, tunnels andsteps at weirs to reduce otter deaths on the road.
© Somerset Otter Group
Occasionally altering a fence line is all that is required to keep anotter waterside and off a road.
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2018 Deaths
So far this year there have been17 dead otters recorded, 15 ofwhich have been secured forautopsy.
One on the River Parrett inJanuary was sadly a lactatingfemale.
With the clocks going back,bringing rush hour traffic intothe dark and rain in theforecast, that number willunfortunately rise.
A fuller breakdown with thefigures added into charts willtake place when all autopsiesare received next year.
Bile Fluke, Pseudaphistomum truncatum
In 2004 wildlife vet Vic Simpson was the first to discover the bile fluke,Pseudamphistomum truncatum, in a British otter from an otter onthe Somerset levels, writing a joint paper on the fluke with his friendJames Williams.
In 2009 Simone Gentner conducted a study into bile fluke eggs foundin otter spraint in Somerset. Her Dissertation can be found on ourwebsite.
James Williams and the Somerset Otter Group were Case Partner withCardiff University for Eleanor Sherrard-Smith’s PhD study; Distributionof Eurasian otter biliary parasites, Pseudamphistomum truncatumand Metorchis albidus (Family Opisthorchiidae), in England and Wales.
A few otters over the years have died as a direct consequence of flukeinfections but how many otters are dying hidden away out of sight?
This chart shows the spread and numbers of otters with fluke signsthrough the Somerset Catchments.
© Crown Copyright
Otters with fluke signs • Otters free from fluke •
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Coastal Streams EXE TONE PARRETT BRUE SOUTH COASTSomerset Catchments
Otters found with fluke and fluke free, as a proportion of those sent for post mortem.2002 to 2017. Shown by catchment.
remainder
Fluke free
Fluke
The map shows the distribution of otters with signs of Flukeinfection, often a thickened or fibrous gall bladder, between 2002and 2017. The distribution has not changed in the last 5 years withno otters found much further west than Taunton. One suggestionfor the otters to the west remaining fluke free is the snail vectorwhich is apparently absent from fast flowing water.
Otter Dispersal
The fluke presence or lack of itgive an indication of otterdispersal.
In the 14 years that the fluke hasbeen known about withinSomerset it is odd an otter hasnot been killed dispersing westand carrying the fluke. A fewwould surely be expected. Thiscould be an indication thedirection of otter dispersalremains from west to east in theCounty, as in the 1980’s with theotter’s revival.
We will hopefully know morewhen the DNA study fromCardiff University concludes.
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----------------------------------Male and Female
The map shows the sex of deadotters recorded from 1999 to2017.
Not all dead otters reported arerecovered and so not all aresexed. An average of 60% of thedead otters recorded inSomerset have their sex known.
There is a bias towards maledeaths with 193 male and 155female between 1999 to 2017.However that bias is notrepeated every year as can beseen with the chart. There areseveral years when the numberof female deaths are higherthan those of males.
Unusually the bias does notextend to sub adult deaths,with 46 female and 41 male.However these figures are for19 years of records combinedand there can be years whenthe bias applies, but there is noroom here for more than asnapshot of data.
Otter deaths vary considerablybetween the years andfluctuations are often reflectedin the Somerset Otter Groups 2day annual surveys. Illustratingthat however healthy thepopulation appears it is easilyinfluenced. It is so importantwe continue monitoring theotter population in the county.
© Crown Copyright
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Male and Female Otter Deaths by Year from 1999 to 2017
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Male Otters • Female Otters •
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Sub adult males • Sub adult females • Lactating females •
Please report all dead otters in Somerseteither to the Somerset Otter Group direct orthrough the Environment Agency.
All of this publication is subject to© Somerset Otter Group.No portion to be reproducedwithout express permission.
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