Theses and Dissertations

Title: The estimation of channel catfish (Ictalurus punctatus Rafinesque) populations in farm ponds from catch statistics

Name: Hatcher, Robert Marlin

Degree: MS

Chair: Dr. E.W. Shell

Resides: FAA Library

University: Auburn

Location: Auburn, Alabama

Date: 1962

Pages: 104

Keywords: Estimation,Channel Catfish,Populations,Farm Ponds,Catch Statistics.


The Delury Method was used to estimate the number of channel catfish (Ictalurus punctatus Rafinesque) present at the beginning of the fishing season in 3 separate ponds from the catch records of 20,790 anglers at the Farm Pond Project, Auburn, Alabama. The ponds were drained, and the accuracy of the estimates was determined. Estimates were made using average number of channel catfish caught per hour (catch per unit of effort) for intervals of 1 day, 500 angling hours, 800 angling hours, 1,000 angling hours, and 1 week. Within the same fishing season these estimates were not significantly different from each other. Estimates were made using each of the above intervals of effort, with which the catch per unit of effort was calculated for all anglers and for only the successful anglers. The mean error of the estimates from the true number of channel catfish (total accumulated catch plus the number recovered at draining) from catch records from all and from only successful anglers were respectively -2.9% (range of -10.3% to +6.2%) and +32.76% (range of +10.5% to +60.6%). The assumptions of the method were investigated. The assumptions of nonrecruitment, constant catchability, and of taking a significant proportion of the population had to be satisfied to achieve acceptable estimates of population size. The assumption of non-competing units of fishing gear and of constant fishing pressure did not have to be fully satisfied to achieve reasonably accurate estimates. Factors affecting fishing success and the estimates were investigated from the catch records of 24,298 anglers from 5 fishing seasons. Fishing success was poorer on Saturday than on other days of the week during the first two years of estimation but was not different during the last year that an estimate was made. However, there was no difference in population estimates when Saturday's catch per unit of effort was omitted from or included in the estimate. The use of more than 2 units of fishing gear per angler resulted in little or no increase in fishing success (based on investigation of 5,536 catch records from one fishing season). Fishing success was positively correlated with water temperature during the intervals when there had been little effect of population depletion. The ratio of boat-to-shore anglers, barometric pressure, wind direction, and the degree of cloudiness or amount of precipitation had little or no relationship with fishing success.

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