1. Comparison of Fish Ageing Techniques: Using Scales and Otoliths from Largemouth Bass in Old City Lake. Joey Dyer Undergraduate, Department of Biology Tennessee Technological University Cookeville, TN 38505

2. Project Summary The objective of this study is to compare the two most common aging techniques of bass. The techniques are using the scale and otolith method. The scale method is the easiest of the two but not as precise as the otolith method. The problem with using the otolith method is that the fish is sacrificed in the process.

3. Scale Method Otolith Method

4. Introduction The use of hard parts is based on the appearance of annuli rings (Kruse et la 1995). Historically, scales have been most often used (Weisberg 1993b). Otolith samples are more accurate ( Eveson et la 2004).

5. Hypothesis Statement Although the fish will be sacrificed, the otolith sample will give a better estimate of the fishes age, due to the regeneration of scales that have been lost prior to capture.

6. Methods and Materials 14 bass were collected from Old City Lake by electro-fishing Scale samples and otoliths were removed Annuli rings on both scales and otoliths were recorded Rings pressed and counted under a projector for scales Rings counted under a microscope for otoliths

7. Data Form

8. Results/Discussion The results of my studies were: 4 out of 14 were the same age 28.6% Otolith age greater in 7 out of 14 50% Scale age greater in 3 out of 14 21.4%

9. Results/Discussion The reasons results may vary Crichton effect ( Simkiss 1974) re- absorption of scales in severe stress Scales may not form annuli in times of food scarcity The otoliths continue to form annuli in any condition

10. Conclusion One person needs to do the readings on the scales and otoliths The otolith samples were more exact The scale method would work in areas were the bass need not to be harmed

11. Literature Cited Caldow, C., G. M. Wellington. 2003. Patterns of annual increment formation in Otoliths of pomacentrids in the tropical western Atlantic: Implications for population age structure examination. Marine Ecology Progress Series 265: 185-195. Campana, S. E., M. C. Annand, and J. I. McMillan. 1995. Graphical and statistical methods for determining the consistency of age determinations. Transactions of the American Fisheries Society 124: 131-138. Eckmayer, W. J., J. F. Margraf. 2001. Ageing early age – 0 white bass (Morone chrysops) by daily otolith increment analysis. Journal of Freshwater Ecology 16: 653- 654. Eveson, J. P., G. M. Laslett, and T. Polacheck. 2004. An integrated model for growth incorporating tag-recapture, length frequency, and direct aging data. Canadian Journal of Fisheries and Aquatic Science 61: 292-306. Kruse, C. G., C. S. Guy, and D. W. Willis. 1993. Comparison of otolith and scale age characteristics for black crappies collected from South Dakota waters. North American Journal of Fisheries Management 13: 856-858. Simkiss, K. 1974. Calcium metabolism of fish in relation to ageing. Canadian Journal of fisheries and Aquatic Sciences 26: 256-267 Weisberg, S. 1993b. Using hard-part increment data to estimate age and environmental effects. Canadian Journal of fisheries and Aquatic Sciences 50: 1229-1237.