Geoscience Reference
In-Depth Information
2003), so our estimates may be too low. Assessing
favourable status using catch records alone is
unreliable because angling effort has not been
taken into account and there is no calibrated
baseline to determine population size under near-
natural habitat and water quality conditions.
Spurious assessment can also result from catch
returns which are cyclical or erratic. Great care is
needed, therefore, in interpreting catch records.
One consequence of small salmon populations
is the loss of genetic variability. This may not be
a major problem for salmon in northern Spain
because high levels of dispersal and asymmetric
gene flow have been suggested as important
mechanisms maintaining the genetic diversity of
these small Iberian populations (Consuegra
et al.
,
2005). Previous studies have shown that the As on
River population is crucial in maintaining the
genetic diversity of Cantabrian salmon (Kuparinen
et al
., 2010). Our assessment indicators for grilse,
females and fry production show that the As on
population could be at a higher risk than the
others. Although salmon stocking programmes in
the region may have been successful in maintaining
genetic diversity, they may not be effective in
reversing population declines in the longer term
(Ciborowski
et al
., 2007). This reaffirms the need to
understand the factors affecting conservation status
and target action to sustain key populations by
improving river habitat and the natural functioning
of river processes.
potential effects of climate change will also be an
important consideration. Because information on
conservation status and pressures can be made
available through a user-friendly GIS system the
benefits of the method as a decision-support
tool to support strategic environmental planning
can easily be demonstrated (IH Cantabria, 2010).
Nevertheless, the assumptions and rule-based
criteria used need to be tested further and refined
to improve confidence in the assessments and their
applicability to areas outside Cantabria.
Acknowledgements
This study was financed by the General Direction
of Biodiversity from the Cantabrian Regional
Government. We thank the many people who have
contributed to the development of the method
and its application for the conservation of habitats
and species within the
Natura 2000
network of
Cantabria.
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the
