When the hen fish are ripe, that is when they are ready to spawn.
They are carefully anaesthetised and then with a firm but gentle action the eggs
are expelled into a bucket. In the past we stripped one hen and then fertilized
the eggs with one cock fish. But recent research had suggested that each hen will
have its eggs covered by several cock fish as well as the occasional precocious parr.




So we have changed our stripping practice.
This is how Ian McMyn our resident Fishery Biologist explained it.

One hen fish is stripped of her ova. The ova are then placed into five different basins. This is replicated
with a further four fish. So now we have five basins with five different sets of ova in each basin.
One cock fish is then stripped of his milt into each basin (five basins, five different cocks, one into each basin).
So now we are in the healthier situation of having one hen fish's ova being fertilised by five cocks.
This is giving us five different families or genetic groups from one hen.
The advantages of this technique are potentially numerous. Returning adults are less likely to meet a
brother or sister on the redds and we should have a "fitter” or better suited animal for its habitat.
Practically, in terms of time taken to strip and fertilise the ova this method hardily takes any longer
than using the traditional one‑to‑one technique.
As a final note I would like to add that hatcheries need to be used with caution in fishery manage­ment.
They are one tool in a large box that is at our disposal. It needs to be remembered that wild fish – choose
the right mate at the right time in the right place". However hard we try, we will not be able to replicate the
natural spawning that occurs in our rivers every year.
lain McMyn, Fishery Biologist.