Estimation of Bass Numbers in a Farm Pond Prior to Draining with Electro-Shocking and Angling

The number of largemouth bass (Micropterus salmoides) in a 3.5-acre experimenbal pond located at Auburn University Agricultural Experiment Station was estimated by mark and recovery techniques using both Schnabel and Peterson methods. Sampling was done wirth both electric shocker and angling. Estimates were made during two periods in 1962. Various estimates of the number of bass made in this study were fairly uniform. However, on draining the estimates were found to be in error by approximately 50 percent. Based on number of bass recovered at draining and the computed percentage of survival, the value of N for the first period (May 23, to December 20, 1962), was computed to be 604 bass, whereas the Schnabel and Peterson methods gave N values of 304 bass and 469 bass with percent errors of -49.7 and -22.4, respectively. The theoretical requirements of both methods seemed to be met for the first period. The value of N for the second period (August 1 to December 20, 1962) was computed to be 500 bass, whereas the Schnabel and Peterson methods gave N values of 381 bass and 313 bass with percent errors of -23.8 and 37.4, respectively. The requirements of no mortality for the Schnabel method was violated without any apparent loss of accuracy. Only with the Peterson method during the first period were the criteria of Robson and Regier (1964) satisfied for censuses with management applications. None of the censuses met their criteria for censuses with research applications.

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