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

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.

Scale Method

Otolith Method

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).

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.

Methods and Materials

• 17 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

Bass

Age b

y Oto

lith In

Yea

rs

Age b

y Sca

le M

ethod

In Y

ears

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101112131415161718

Data Form

Expected Results

• Otolith samples will be more precise but the fish will have to be sacrificed in the process

• The scale method will give a good estimate of the fishes age

Project Timeline

       Research Topic/Title (Research title was developed) Week(s) 1-2

• Library Literature Search (Searched for relevant literature) Week(s) 2-4

• Scientific Method Objective/Hypothesis (Developed matrix, objective and hypothesis) Week(s) 3-6

• Research Proposal Key Words (determined good keywords) Week(s) 4-6

• Web Page (began development of the webpage) Week(s) 5-9

• Data Form / Format / Midterm Outline (developed a data form, learned the format for the research proposal outline and drafted the outline) Week(s) 5-6

• Research (compiled and analyzed data, completed research) Week 5-6

• Abstract (began writing the abstract, summary and conclusion Week 5-6

• Midterm (gave research proposal presentation) Week 7

• Spring Break Week 8

• Platform presentation (started developing presentation) Week 9

• Developed a resume and Ethics statement Week 10

• Designed poster and had the manuscript evaluated. Week11

       Wrote a research progress report Week 12

      Rewrote the research proposal as a research proposal application Week 13

       Time for the platform presentation Week 14

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.

 • Weisberg, S. 1993b. Using hard-part increment data to estimate age and environmental effects.

Canadian Journal of fisheries and Aquatic Sciences 50: 1229-1237.

Budget

 • Salaries & Wages 10,000• First Year• Professional• Technician• Secretarial• Graduate Student• Student Hourl• Subtotal• Benefits• Travel• Non-Expendables 2,000• Expendables 1,000• Computer • Supplies & Expenses 2,000• Copying & Telephon• Tuition & Fees• Subtotal 15,000• Total Direct Costs• Indirect Costs• Total Costs 15,000