Here is the latest official statement which seems to contradict some of that reported by Paul Boichat.

I see the usual arrogance about not responding to their own members on Forums etc....

There are still big issues:
a. If the lake contained 850 fish before the stocking, why stock it?
b. What happened to the Horseshoe carp breeding programme? Did they sell the fish off?
c. Are they stocking again next year as planned and running the risk?
PRESS STATEMENT
It has long been estimated that Horseshoe has in excess of 1000 big fish, ie doubles or more. We estimate around one hundred of 30+. In the last eleven years we have never lost more than about 20 fish in any one year.
The first restocking last year was part of a five year plan recognising that many of the fish in the lake are over thirty years old. When we introduced the 180 small doubles we were told we may experience a slight increase in the number of mortalities as the new fish acclimatised.
We did not lose any fish through the extremely hard winter we have just had. The first notable sign of an increase in the level of deaths was over the weekend of 13/14 August and so we closed the lake on Monday 15 as a precautionary measure. Including the very recent deaths, we estimate that we have lost between 50 and 60 fish since the Spring.
Following our request for an EA inspection, their officer observed that there are absolutely no fish showing any signs of distress, nor on inspection of the dead fish was there any sign of obvious disease. This is puzzling to both the EA and the fishery scientist who independently inspected the fishery. Even though the EA saw no reason to health check the fish, they have now agreed after seeing our concern. The post mortems will be carried out next Thursday which is the earliest they can arrange and they tell us that the results will be with us within 10 to 14 days.
Asked for his overall opinion on why we may have lost fish, he surmised that a combination of a very poor spawning season, extremely low water levels and high overall temperatures, all of which are stressful conditions, have, and are, causing problems throughout the region.
The 50-60 fish we have lost have been in the mid doubles to lower twenties. This means that the head of fish in Horseshoe is still well over the long held estimate of 1000, which includes around 100 of those being over the 30lb bracket.
People have asked us why we are not responding to forum speculation. It is not our policy to partake in forums, using instead our website to communicate to all interested anglers.
We will continue to seek expert advice and as a precaution the lake will remain closed whilst we go through this very difficult period. Our priority is the lake and its fishing as it always has been.
We would encourage all anglers is to stay in touch with us directly. Please bear in mind nobody could be more concerned than we are over this recent development. As to opening date, it entirely depends on any further advice given by the EA and on our own monitoring of the situation. We will continue to post updates as information becomes available.