from
http://www.otter.org/documents/IOSF%20Otters%20and%20Fisheries%20Conference%202012%20Edinburgh.pdf
There is significant misunderstanding about the role of re-introductions and captive-bred releases in
the recovery of otter populations, and whether these are indeed still occurring. In fact, there have
been relatively few otter reintroductions in the UK when the timespan of the recovery period is
considered. The Otter Trust released 117 captive-bred otters over a period of 15 years, but agreed
to terminate this programme in 2000 following concern about local impacts of some releases and
pressure from the UK Otter BAP Steering Group, who felt that captive-bred releases were not
necessary to secure the recovery of the population. These are the only known captive bred otters OSF Otters and Fisheries 7
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November 2012, Edinburgh
- 26 -
released in the UK. The last release was of 17 otters in 1999, and a number of these were killed on
the roads in the following months, illustrating the potential mortality rates experienced by reintroduced animals. Between 1990-1996 the Vincent Wildlife Trust released 49 rehabilitated
animals, mainly in a carefully planned release programme in Yorkshire. Currently, there are a small
number of releases of rehabilitated wild otters each year, predominantly orphaned cubs released
back to the wild once they are old enough to fend for themselves.
The recovery of otters to their levels of 60 years ago has largely been achieved by the natural return
of otters from areas where they never died out, with re-introductions making a small contribution to
speeding up the recovery in certain areas. As the environment has improved and levels of toxic
pollutants have declined, the environment has been able to sustain otter populations once again.
and
Ecology of Predation: some sectors of the angling press claim that there will be an endless increase
in predators such as otters unless they are controlled, but in reality, predator numbers are largely
determined by prey availability and, in some circumstances, access to breeding sites. Simplistically,
territoriality has evolved as a means of dispersing predators in the landscape at a density that food
and other resources allow and can support. A healthy population of aquatic predators indicates that
the whole of the rest of the ecological pyramid is in good condition – fish, fish prey, habitat, water
quality etc.
In lowland Britain in particular, still waters are mainly artificial, often based on gravel pits and
reservoirs, and many were developed as fisheries during the time that otters had been lost from
much of the country. Otters came back to an environment with damaged or recovering rivers and
with many more stillwaters managed as intensive or specialist fisheries. A proportion of these
fisheries contain predominantly large specimen fish. In the winter particularly, when there is little
else available and these large fish are more torpid, otters can easily catch and kill them.
Over the last few years, in recognition of these concerns, the EA has put aside a moderate amount of
funding to help fence fisheries to keep otters out, with an emphasis on day ticket fisheries, as this
benefits far more people than private syndicates and private club waters. This is based on the
principle that the funding is for the promotion of angling, and emanates from a fisheries funding pot.
Not all of the potential funding is taken up each year.
The EA has also worked with the Wildlife Trusts to develop advice for fishery managers on methods
of preventing access by otters to fisheries. This guidance document - ‘Otters and Stillwater Fisheries’
– is on the EA website. There are a number of companies that can provide and/or erect otter-proof
fencing.
The amount of damage from otter predation to a fishery is greatest where there are large, uniform
ponds with poor marginal structure and little cover, and those which are populated primarily by
large fish. Better fishery habitat management, introducing more marginal vegetation and woody
debris for cover, and a healthier fish population age profile can help reduce predation impacts.
