The Dorset Otter Group are carrying out an important role monitoring the long-term population changes of otters. The information gathered by DOG will help us look critically at these results within each catchment and identify future priorities such as habitat enhancement, water quality issues, etc with Bronwen. The following is a summary and analysis of all results collected from Dorset and set in the context of the national picture.

Analysis of DOG Results

Over the past 4 years the DOG volunteers have spot-checked: -

Although there has been a 50% decline (mainly due to flooding and the Foot and Mouth crisis) in the number of sites checked, there has been a 15% increase in the number of positive sites over the last 4 years.

Over the last 2 years the result details have been as follows: -

Converted into percentages this relates to: -

These results were then incorporated into the relevant catchment areas: -

* The South Wessex Otter Strategy 1998 set out Biodiversity targets for these catchments in South Wessex for positive occupation by 2010.

The number of spot checks has declined 40% during over the last year (due to the Foot and Mouth Crisis) but this has not resulted in a decline in the number of positive sites. In the majority of cases the number of positive sites has actually increased.

Summary of results over the last year: -

Avon

There was a 15% increase in the number of sites checked last year and this resulted in a 30% increase in positive sites (from zero in 2000).

Corfe

The number of sites checked decreased by 40%, still no positive results.

Frome

The number of sites checked decreased by 36% but there was a 9% increase in positive sites.

Piddle

The number of sites checked decreased by 40% but there was a 10% decrease in positive sites.

Sherford

No sites were checked last year, a drop from 14 the previous year – no positive results.

Upper Stour

The number of sites checked decreased by 34% but there was an 8% increase in positive sites.

Lower Stour

The number of sites checked decreased by 48% but there was a 15% increase in positive sites.

West Dorset Streams

The number of sites checked decreased by 31% but there was a 7% increase in positive sites.

Wey & Fleet

The number of sites checked decreased by 52% and there were no positive sites (there had been only 1 the previous year).

Conclusions

Overall although less monitoring took place last year the number of positive sites has increased quite dramatically.
Is this a true reflection of the situation?
Are the volunteers who monitor the sites doing so because they are encouraged by finding otter signs and others monitoring negative sites stopped because they are discouraged?
Bronwen Bruce, Rivers & Wetlands Officer at DWT has confirmed that this is not the case. There does not seem to be a correlation between negative sites and people continuing to survey them, one of the biggest influences on results is the number of volunteers available. It should also be remembered that volunteers often have different capabilities which may effect their ability in getting results e.g. mobility, access to river, do they own waders, etc.

The National Otter Survey results are due out shortly, the sites included within this survey were all surveyed by Bronwen and she feels this would act as a good "control" against the DOG results. Hopefully the results will reflect the same increases in positive sites as shown by DOG.

We would like to take this opportunity to thank all the DOG volunteers; we really appreciate all the effort put in by the members and Bronwen and finally, would like to assure you that the information gathered is being put to good use.

Sandie Moors & Emma Rothero
Technical Officers
Fisheries, Recreation & Biodiversity
Environment Agency – South Wessex

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