Purpose:

The purpose of this study was to estimate the population of small mouth bass in "The Beauerle Pond" in Bardstown, Kentucky using a mark and recapture procedure. Common techniques and methods used in executing such studies were also demonstrated. In addition to being tagged, captured fish were also measured for approximate length and their capture location was recorded for estimation of population distribution.

The "Beauerle" Pond

The pond is located in Bardstown, Kentucky, approximately 45 minutes from the greater Louisville area. The pond was created in 1981 for irrigational purposes and was stocked three years later. The stocked species include bluegill, ,channel catfish, and small mouth bass-the focus of this study. The average depth of the pond ranges from 14-20 feet and is currently 6 feet below the average water level.

Facts about Small Mouth Bass

The average length of small mouth bass ranges from 10-20 inches and they usually weigh anywhere between 1-5 pounds. Bass in general are a cold-blooded schooling fish that usually reside near the bottom of their respective body of water. Small mouth bass generally spawn in early summer months and choose gravely areas to make their nests. They are often found in clear, rocky waters with little vegetation, and feed on a variety of organisms including minnows, crayfish, and insects.

Fundamental Assumptions of Mark and Recapture Models

• The population is closed (geographically and demographically)
• All animals are equally likely to be captured in each sample
• Capture and marking techniques do not affect catchability
• Each sample is random
• Marks are not lost between sampling occasions

* A closed population is a population in which there is an absence of both recruitment (birth or immigration) and losses (death or emigration) during the period of study.

Methods:

This study utilized the Schnabel Estimator model for closed population mark and recapture experiments. The equation for this model can be seen below:

Three sample collections were performed on three separate dates. The initial collection took place on October 23^rd with the subsequent collections taken on November 11^th and November 23^rd respectively. All fish were caught using artificial night crawlers. Each fish was marked with a clothespin-like tag inserted into the flesh of the lower lip. All captured fish were marked for each sample and also measured for approximate length. The location of each capture was also recorded for later analysis of population distribution.

Results:

The table below illustrates the results of each sample collection. Recaptured fish are shown in red, and the average length of captured fish for each sample collection is also noted.

The figure on the left is a graphical illustration of the pond and its appropriate division into segments for fish distribution analysis. The pie chart on the right displays a statistical analysis of this distribution relative to each section. The results indicate an increased capture rate in sections three and four.

Conclusions:

Results of fish length analysis gave an average of the length of captured fish to be ~10.44 inches. The size range varied from 8 inches to 15 inches, indicating a stable mixture of adolescent and adult small mouth bass.

By using the Schnabel Estimator, the approximate population of small mouth bass was calculated to be ~90. It must be noted that this calculation is a very rough estimate at best. Mark and recapture studies such as this can be influenced by a variety of factors including, but not limited to, number of samples analyzed, number of animals caught in each sample, variations in weather as well as fluctuations in water temperature.