The temperature is cooler? That can't possibly be the only reason to explain such a dramatic change in survival rates. We definitely need more research on this topic.
If you do even a moment of reading about salmon, you will find that they are extremely sensitive to warm temperatures. Even a couple degrees F above their "normal" will allow disease to run rampant.
If you do even a moment of reading about salmon, you will find that they are extremely sensitive to warm temperatures. Even a couple degrees F above their "normal" will allow disease to run rampant.