The shapes of fish otoliths vary highly among different species but not within species. Layers that are mineral-rich and mineral-deficient are deposited in alternating succession around the original center of the otoliths, creating bands that resemble rings on a tree. The bands show up as dark and light areas when viewed under a light. The rates of deposition vary during different times of the year. During the summer months, warmer water and rapid growth cause the otoliths depositional rates to be more rapid than during winter months. By examining the otolith, we can tell how many seasonal changes a fish has experienced during its life, allowing us to determine the fish's age. This is an important tool that is used not only to determine age, but to also identify different stocks.
|Water chillers at Quilcene NFH|
|Kokanee egg trays at Quilcene NFH|