How do you tell how old a crappie is?

[LSL Angler]

Just wondering how you tell the age of a crappie? Is there any way by just looking at the fish or is there a special test that you have to do to determine its age. On some lakes where the crappie are stunted you say a 3 year old fish can only be 6 inches long. Thanks for answering all our questions.

[Eric Dennis]

We have a couple of ways to get age data for crappie. One way is to take scales from the fish. Fish put down daily growth rings on their scales similar to the rings on a tree. When growth slows down, usually in the winter, these daily growth rings start to bunch up forming a thinker, darker ring. When you press the scales and look at them under a microscope you can count these annual rings starting in the center of the scale moving out. Each thick ring equals 1 yr. of life. You can also tell how much growth occurred between yrs. based on the distance between these annual rings. A bigger distance between annuli indicates better growth, tighter lines stunted growth. The good thing about using scales is that it is a non-lethal method. The problem with using scales is that often times they can be difficult to read and may cause us to get an inaccurate age. These rings really stack up on older fish and become hard to read towards the outer margins of the scale and fish can also regenerate damaged scales, leading to inaccurate readings.


Another way to get more accurate age data is to take an inner ear bone out of the fish called an otolith. These structures also put down daily and annual growth rings. The good thing about otoliths is that you don't have to worry about regeneration and I think they are much easier to read. We cross section the small bone, sand it down flat, and put it under a microscope. When you shine a fiber optic light on the otolith the annuli kind of glow making them easier to count. The bad part about taking otoliths is that it is a lethal method.

In both cases, scales and otoliths, we usually take around 5 fish per half inch group to get an accurate data set. Obviously some fish grow faster than others so taking multiple fish is a must in order to get an accurate length/age data.

[FROSTY]

[Jigging15]

And we know from other threads in this section that it is an old black crappie. Got to love the new biologist section.

[olesilverside]

If you catch me and I am in my wheel chair, throw me back, I am to tough to filet........

[KCMO CRAPPIESLAYER]

funny stuff frosty

[Double D]

Not to mention just plain ol mean.

[MOfishmgr]

Eric did a great job explaining our aging methods. We much prefer using otoliths because our confidence is very high when aging them. However we are very reluctant to kill fish in our jobs. As a aresult we only do aging work every few years. In order to prevent killing legal fish, I have gone to the cleaning station at Smithville when the docks open for fall fishing and taken otoliths from folks who are cleaning their catch. I even took a couple days off and fished with the folks and they really got into providing fish for me. To a person they were really interested in seeing where these bones are located in the fish too. I got to know a good group of guys and made some friends along the way. To get the otoliths from sub-legal fish we did have to take them from our nets, but like Eric said it's only 10 per inch group and that's too few to impact the population even on a small lake. I just wanted to let you guys know that we take sacrificing fish for our data very seriously. On the rare occasion we do, it has a good purpose and we try to minimize it as much as possible.

[MOfishmgr]

In southern states the biologists must use otoliths. Scales lay down too many false annuli due to the lack of true seasons in the deep south. When I worked in Florida, we used otoliths exclusively. In Missouri, scales can be used fairly accurately on very fast-growing populations, but even populations with average growth dictate the use of otoliths.

[cschottfish]

Nicely said gentleman and very well put .