Hiya mate, that looks like a nice place to fish you have there. I fish for pike on the fly in a chain of reservoirs near where I live and it is not uncommon to find dead pike up to double figures in weight after spawning has taken place. You do not generally see dead fish washed up but for a couple of weeks a year you may find them. Perhaps your fish was just an old hen at the end of her life. Another theory is that trout water pike can grow very fast due to the high protein diet available to them in the shape of rainbow trout. A trout water pike with a small head and a large (fat) body may be a young, fat fish that will not stand up well to being stressed and can die as a result.
The reservoirs I mentioned used to be subject to a close season rule between March and June. The pike fishing was excellent. Then they were opened up to all year fishing and the pike were not left alone. An interesting trend developed. When the close season ruling was in place, after the season started you would catch loads of pike on lures, both surface and subsurface. Some of the lures used were huge jerkbaits but it did not matter to the pike, they hammered them. Then more and more people started to fish for them and the close season was abolished so the pike were subjected to year round pressure and results started to tail away. Follows instead of takes became common. We had to start using smaller, more subtle lures like jigs to get results and even they became ineffective after a while so we turned to flies. The point of all this is that the pike do not respond well to year round fishing pressure and it is the opinion of some anglers that the quickest way to kill a pike water is to allow year round fishing for them. After all, pike thrive on neglect.
I would be very interested to know how the pike in Gailey are responding to year round fishing and if it corresponds with the fishing in my local waters.
Also, what type of trace material is recommended for the pike fly fishing there as there is nothing on the fishery rules part of the website about it. It looks like a really nice water to fish and I will definetly have a cast there this season.
All the best and good fishing,
Andy.