The exact age determination of fish is one of the most important elements in the study of their population dynamics. It forms the basis for calculations leading to a knowledge of the growth, mortality, recruitment and other fundamental parameters of their populations. Otoliths are a far better sample to accurately age trout than scales. Scales become quite useless after 3-4 years of age and thus, their limitation in trout that can be 8, 9 or more years in age, depending on species. In fact, this was noted in a scale sampling years ago from the Snake River, but the results were incorrectly interpreted out of context as “trout only get to 4 years old”. The number of trout sampled, and killed, was perhaps not statistically significant as killing 400 trout, but sufficient to recognize age groups and comparable to data from the early 1980s. Not dated, to be sure, but simply a biologic survey to check on the health of the trout from time to time. Interestingly, I was able to obtain 4 trout 18-22.5 inches on a single day by walking around the cabins and inquiring whether any fisherman had sizable fish that I could dissect for otoliths. The number of trout killed for the survey was inconsequential. They are a renewable resource and we are focused on protecting the fishery for future classes and trophy fish.
To that end, the otolith analysis was an essential part of implementing new regulations to fit the fishery and the anglers. Furthermore, the condition of the otoliths along with weights and lengths obtained during the survey indicate a very healthy trout population. This, in September, after 3-4 months of low water conditions and summer months. And…high angler presence. So, the trout are thriving, despite the sometime hysteria and sky is falling anecdotes.