The OED defines an elder, simply, as the senior of two or more individuals - no age specified. 'Elder', as an adjective, conveys the same meaning. This is an interesting question. There are no standard industry answers, just as there isn't a standard label (senior, senior citizen, elderly, old, 65+, etc.)
Bake the trout for 10 minutes, then unfold the packet far enough to check the doneness. When done, trout is moist and flaky with an opaque appearance. Return the fish to the oven and continue baking if necessary. Trout usually cooks within 20 minutes, but may require up to 30 minutes, depending on the size of the fish.
4. Pour one tablespoon of the melted butter into a frying pan over high heat. Place trout skin-side down into the pan and cook for 2-3 minutes until the bottom is browned. Use a spatula to flip fish over, reduce the heat to medium, and allow the other side to cook for 2-4 minutes.