Graduate Program

Environmental Biology

Degree Name

Master of Science (MS)

Semester of Degree Completion


Thesis Director

Michael Goodrich


One hundred largemouth bass, ranging in size from 148mm to 385mm, were equally divided into four treatment groups (control, tag only, tag and left pectoral fin clip, and tag and all paired fins clipped) , and placed into a 5.56 hectare pond on 22 May and 25 May 1979. Upon recovery on 28 September 1979, the increase in length from the time of most recent annulus formation was found to be significantly greater in Age I control fish (x̄ = 125mm) than in fish of the same age in the other three treatment groups (x̄ = 110mm, 103mm, and 106mm, respectively). Lengths at time of recovery were also greater for Age I control fish (x̄ = 264mm as compared to 256mm, 246mm, and 244mm), as well as for the controls in the combined Age III and IV class (x̄ = 387mm, 354mm, 343mm, 336mm, respectively). A mean weight gain of 229g for the Age II tag only fish was found to be significantly greater than the mean gains of 180g and 177g reported for the Age II tag and left pectoral clipped and the tag and all paired fins clipped fish, respectively, while the weights reported for the time of recovery showed that the Age I control fish were heavier (x̄ = 260g) than the other three treatment groups (x̄ = 241g, 222g, and 204g).

Observations of largemouth bass in laboratory aquaria revealed that fin clipping does not offset the advantage of greater size in determining social position. Dominant bass consistently captured more food and there was little evidence that fin clipping impaired the predatory abilities of the bass under observation.

The fact that a significant reduction in length and weight gains is possible due to fish marking techniques indicates that caution should be exercised when dealing with data on marked populations of fish.