This is not a fishing blog, but every now and then I will post something along those lines. For a few years now I have been chasing bull trout on Lake Billy Chinook using fly gear. It’s challenging but can be rewarding. Above is a photo of one of my sons with a nice bull trout. There are a lot of variables at play, but it looks like we could have a good and early season. Here’s what I have been looking at.
As you can see in the graph below, there are still a lot of kokanee in Lake Billy Chinook. Their population is cyclical but still near the top of the current peak. Kokanee are the primary prey for bull trout so it stands to reason that there should be plenty of bulls, and big ones. A warm winter and low snow pack is bad news for steelhead and salmon reintroduction efforts but it should be good news for bull trout fly fishing. I don’t like algae on LBC more than anyone else but it does provide cover which will bring kokanee and bull trout up to the surface and in range of my fly line. High water clarity due to a cold, windy spring was a problem last year for fly anglers.
Side note: It is thought that the kokanee population is cyclical for the simple reason that once the population grows beyond the carrying capacity of the reservoir the population will drop before rebounding. This is typical for kokanee in many water bodies. It is unknown why they do not achieve a population equilibrium commensurate with the carrying capacity of the environment. LBC seems to be on a 7-10 year cycle with 2017 being the latest peak. Bull trout fishing will likely decline over the next 3-5 years as the number of prey diminishes.
On the other hand, kokanee anglers should start seeing improvement. As you can see in the chart below, there is an inverse relationship between kokanee abundance and size. As the population falls there should be more food for the remaining fish which should allow them to grow. In a couple of years it will be time to stop chasing bull trout and go after kokanee instead.
BTW, both charts are from PGE/CTWS. Go to their website and sign up for their newsletters to get this sort of information.