Step 2: Imaging

After the fin rays have been prepared in the lab, they are examined under a microscope to get a better view of the annuli. A microscope with a camera is used to obtain digitized, detailed pictures of each fin ray sample.

Step 3: Aging

Individuals in the lab observe each fin ray image and count the annuli. Each annulus corresponds to a single year of growth and appears as bright white bands. Once the annuli are counted, the age is estimated by adding up the total number of annuli (Figure 5). Obtaining accurate ages from fish is important because it helps provide valuable information on their life history, age composition, and population structure.