Dr Wesley Neal had an interesting article in the latest PB magazine about rainbow trout as bass forage. While he acknowledged that LMB love trout and seem to grow especially well on a trout diet, he argued that stocking winter trout for the purpose of feeding LMB is mostly futile. Too much expense for too little LMB gain. He makes a good case, and I've had to reconsider my plans to stock trout in a few weeks.
Frank, about half the cost is the trout and the other half is the feed if you choose and appropriate commercial trout feed. If you use optimal or purina formulations for predators, it will cost as much as former just for the feed. First, one needs to match the feed to the fish.
Feeding forage isn't a cost efficient way to grow predators. Feeding predators the feed directly is very cost efficient. The reason deals with conversion ratio of forage weight to predator weight.
I think feed targeted to raising appropriately sized trout will be more cost efficient than the same quantity target to feed large BG. I would think that the majority of feed of you are feeding BG is going into putting weight on the largest BG. That introduces inefficiency simply because the BG that directly benefit are the ones that the LMB can't eat.
But then feeding BG produces manure and this manure stimulates the base of the food chain creating a bloom of micro-organisms. It is this bloom that provides cover to young BG fry and lots of food. And so production BG YOY is what is going to grow your LMB. So this begs the question, if the "REAL" benefit to the LMB is a secondary effect of feeding .... is there a way ... to shift the use of feed to another organism so that the primary consumption of feed grows forage the LMB are going to eat? The RBT is a good organism for this. It can easily double in length (8-tuple in weight) over the winter growing season and provided it isn't too big at the end of the season, can make ideal forage for 18" to 25"+ LMB.
The cool season provides these benefits.
1. Non competitive environment with existing community members. The rainbow trout are active, the BG are not. The feed goes to the trout.
2. Less predation especially with TP and BG YOY in the water. These alternatives will draw the predators because they will be easier to capture than trout in cool water. Survival over winter should be good provided they are introduced in water cool enough to slow the metabolisms of predators and alternative prey. Slower metabolism, especially for prey alternatives will provide an energetic cost advantage to the predators that they will exploit.
Were I doing this I would seek to stock 4" to 6" Trout when water temps fall below 60 degrees. I would try to grow the trout to a mean length of 10" and if it looked like they may achieve it prior to March 31st I might slow down the feed rate (natural foods may be supplying sufficient growth to complete the cycle). If you feed as much as would in the summer, you should have a great bloom going when the BG start spawning in spring and the first spawn should be very successful. You may not even need to feed the BG the rest of the year. The secondary effects of feeding should be very similar but I would mention that spring is VERY, VERY good time to have nutrients in the water and a good bloom. A good bloom will also reduce FA.
Under this scenario, all of the feed goes to grow forage for your LMB. No feed is wasted unless something other than your LMB is taking your trout (like poacher, otters, osprey, eagles, and cormorants). IMHO, you will get more benefit from feeding trout than feeding BG and I think its a viable strategy to shift feed use to the winter if the purchase of RBT isn't cost prohibitive for you.
