Annabel wrote:

What concerns me is that if a pond is isolated and spawn introduced,
then a resultant population will genetically inbred. To overcome this
spawn should be introduced from many genetically different sources, but
how many sources would be needed?


The inbreeding problem will apply if "your" population is established from
only a few "founder" individuals. It is not necessary to mix individuals
from different sources to ensure adequate genetic variability, just to make
sure that enough variation from the source population has been introduced.
A clump of frog spawn pretty much corresponds to a single female's output
so if you introduce several clumps you will already have some variation. In
the subsequent few years, you will want to add more spawn since it will
take any froglets from the first lot 2-3 years to mature and start
breeding. During this time, you are likly to have built up quite a lot of
variation. Of course, this assumes that the source you get them from is not
inbred itself!

Inbreeding is often less of a problem for many animals than people seem to
think it is. Garden ponds are becoming an increasingly important resource
for amphibians and personally I think it would be unwise to let the
problems with disease etc deter people from establishing new populations.
At the same time, spreading disease is a serious concern so you should do
it in the most responsible way. I would suggest contacting your local
herpetological group (a list can be found on the froglife website) and
asking their advice. They should be aware of the presence of disease in the
area, and be able to possible sources of spawn.

You also mentioned newt and toad spawn. Toad spawn is much more difficult
to move becuase it gets produced in long strings that are wrapped around
pond vegetation, and toads geenerally prefer large ponds with deeper water
and so are less suited to garden ponds anyway. Newts lay their eggs singly
on marginal broad-leaved vegetation, starting a bit later in the spring
(May is a good time to look around here in North Wales, don't know about
your area). Make sure you know the difference between great crested newt
eggs and the eggs of the other species because you would be breaking the
law to take great crested newt eggs. We established palmate newts in our
pond by putting in adults that were being evicted from a friend's pond when
he was renovating it. They've been in there all year now (inlcuding over
the winter) and there are quite a few newt larvae around too.
Anita