Have you ever wondered how old the fish are that you are catching? This is something I have always been interested in since a young age. Fortunately throughout my research I have been able to learn how to age fish using bony structures. Since acquiring this skill I have been lucky enough to give aging seminars for the Saskatchewan Wildlife Federation (SWF) and Cabelas. After these talks anglers are often interested in where they can get more information in case they need a refresher- as promised, here you go! If you are a teacher I encourage you to use these resources to conduct a fun how-age-fish lab in the classroom. Here I have attached couple resources that you can use to age your fish. If for some reason any of these links don’t work for you don’t hesitate to contact me on my contact page.
The following instructions are to be used on dead fish (e.g., the fish you kept for dinner). For a non-lethal aging please see how to use scales (how to with scales: http://www.dnrec.delaware.gov/fw/Fisheries/Documents/agegrowth.pdf)
Questions you can directly answer with age info include:
– How long does it take for a fish to get a certain size? (e.g. harvest size)
– How fast do fish from one lake grow compared to another (do they reach a certain size sooner?)
– How long does it take to replace a harvest-sized fish in a given lake?
– Are small fish small because they are young or because they grow slow?
Biologists further use age info to develop size-age relationships (growth functions) and track changes in population structure and dynamics over space and time.
How to age with opercular bones: Works for Perch & Walleye
For aging perch and walleye I have attached my “guide to aging perch and walleye.” This article is also published in the Outdoor Edge magazine Winter 2014 issue in case you have a subscription. Using these instructions you will be able to age your perch or walleye with the opercular bone. This technique will likely work on other similar looking species but does not work well for pike or muskie (see next section). Within the article I describe how to remove the opercular bone, but if you are unsure just watch the video below from one of my aging seminars at Cabelas.
NOTE: This type of aging is based on the assumption that one annuli = one year of growth. It is important to note that this is not always true species in warmer waters, or extremely slow growing fish. Before aging a certain species it is best to do some searching on what is known about estimating ages with bony structures for that species. It is possible that researchers have completed aging validation studies for that species and have recommendations on the best approach. Aging with the opercular bone is not always the preferred approach, but it is a method that can be done without special equipment- making it an attractive approach for “at home aging”.
How to age perch & walleye article
How to age with the Cleithrum: Works for Pike & Muskie
The preferred way to age pike and muskie is with the cleithrum bone unless non-lethal sampling is preferred. Aging pike and muskie with scales works reasonably well so see the link above if you want to age a pike or muskie during catch and release. Counting the bands on the cleithra is just like counting the bands on the opercular bone except that the bone looks quite different. Below is a picture outlining how the bands look on the cleithra. Just like perch and walleye I have included a link to a video which will show you how to extract and prepare the cleithra for examination.