IUCN/SCC Otter Specialist Group Bulletin
© IUCN/SCC Otter Specialist Group

Volume 28 B: Proceedings XIth International Otter Colloquium, 30 August -4 September 2011, Pavia, Italy

Abstracts

Ecotoxicology of the European Otter (Lutra lutra) along Loire River (France) and Predictable Trends due to Global Change
Pages 5 - 14
Charles Lemarchand, Rene Rosoux and Philippe Berny
In this study, about fifty otters from the basin of the Loire River (France) were analyzed in the context of a toxicological study funded by the Plan Loire Grandeur Nature. Individuals were recovered non-invasively, using a network of collection of otters killed by traffic collisions with vehicles. The chemical elements analyzed were the organochlorine and organophosphorus pesticides, carbamates, pyrethroids, herbicides, anticoagulants, PCBs and metals. Detectable levels of organochlorine pesticides and PCBs characterized all otters analyzed, with mean values reaching 2-15 mg kg^-1, respectively. Concentrations of other analyzed pesticides remained very low. For metals, contamination of otters was systematic for lead and mercury, the latter being relatively abundant in tissues of several individuals. A significant trend to increasing concentrations of pesticides and PCBs by going towards the downstream parts of basins was shown. The inter-individual variations in concentrations were marked. Global values of contamination were below the toxicological threshold defined for the conservation of the species, and the current dynamics of populations within the basin of the Loire seems to confirm this. However, the potential effects of mixtures of compounds remain poorly studied.
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How To Calculate Range And Population Size For The Otter? The Irish Approach As A Case Study
Pages 15 - 22
Ferdia Marnell, Lughaidh Ó Néill and Dierdre Lynn
All EU Member States are obliged to submit reports to the EU Commission every 6 years, detailing the conservation status of species and habitats listed on the Habitats Directive. The otter (Lutra lutra) is one such species. Despite a number of national surveys that showed that the otter was widespread across the country, in Ireland’s 2007 conservation status assessment the otter was considered to be in unfavourable condition. While the Range, Habitat and Future Prospects categories were all considered favourable, Population was deemed to be unfavourable.
This paper examines the data behind the 2007 assessment by Ireland, which included three national otter surveys and a series of radio-tracking studies. Range was mapped and calculated based on the results of national distribution surveys together with records submitted from the public. Population size was estimated by calculating the extent of available habitats (rivers, lakes and coasts), dividing that by the typical home range size and then multiplying the result by the proportion of positive sites in the most recent national survey.
While the Range of the otter in Ireland did not decrease between the 1980/81 and the 2004/05 surveys, Population trend was calculated as -23.7%.  As a consequence, the most recent national Red Data List for Ireland lists the species as Near Threatened (Marnell et al., 2009).
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