Although my experience with motorcycles is almost none, I wondered the same thing. I've got mountain bike wheels that have alloy rims and stainless nipples that have been abused for 20 years and have zero issues with corrosion. Thanks for the word of caution David...be tragic to come this far only to have my nipples suffer from corrosion.
Interesting article on the Yellowstone Cutts. Cutthroat seem to be much more political than rainbows, browns, and even hybrids and keeping them in tact and not threatened is usually a fairly hot topic. I'm not a biologist but I will say that catching a genuine strain Cutt (whatever the specific species) is just different. We have Greenbacks, Snake Rivers, and Colorado Cutts here.
Oh and I can't comment on eating them because I always let anything go.