Nick -
The salmon eggs, carcasses and fry are only part of the story of the Skagit "trout" and their growth.

For those that reside in freshwater much or all of their lives salmon products are key food sources. This is especially true of the larger resident rainbows who once they reach their third year have full access to those products and are adept at taking advantage of that resource. Some of those rainbows can reach up to 10 years of age and respectable sizes. They can add significant poundage during years with high salmon escapements and favorable flows.

The bull trout dive their strategies with some being year-round stream residents while others make the journey to the salt to take advantage of abundant forage fish (smelt, shiner perch, etc.). Those fish that go to the salt tend to grow at faster rates reaching 20 inches one to two years earlier than the full time residents. An interesting side not is that those life histories are not fixed and it is common for resident fish to go to the salt and fish with previous anadromous behaviors to remain in the river for a year or more.

The sea-run gain much of their grow from the salt as well though interestedly they do not achieve the kinds of growth of the bull typically taking at least 8 or 9 years to reach 20 inches.

These complex and diverse behaviors of the Skagit "trout" produce some unique fish and interesting fishing challenges.

BTW - I see that the Montana state record bull trout is more than a century old. I can report with certainty that the Skagit system produces fish that would challenge that record fish.

Curt