Thread: Panfish Growth

You don't need much magnification for otoliths, but the best way to look at them is crack them in half, sand the cracked edge with very fine sandpaper and have a light source to direct into the otolith to illuminate the rings. Sometimes they are pretty easy to read without cracking the otolith, but it depends on species, age of fish, etc. Scales are tough because they can be regenerated from traumatic events or just rubbing them off on objects which would make the fish seem younger than it really is. So you need a bunch of scales from the same fish to make sure you have the correct age and higher magnification for many species than otoliths. The older the fish is, the higher chance it has regenerated its scales in the past. For spines, you need a special saw to cut a very thin section to read. The attached picture is a spine section from a 56 inch, 92 pound blue catfish. Just an example of what they look like.

so am i reading it right? is it 18 years old, or do those really faint lines count?

Good read! We came to a consensus of 17+. The + means it is in its 17th year. The outside of the otolith or spine does not count as a annuli. Normally, we have two or three people read the same otoliths. If there is a disagreement among readers, they sit down and read it together until a consensus is reached. We don't usually look at the fish lengths at the time of reading so there is no aging bias.