Analysis of the Petersen Mark and Recapture Method for Estimation of Fish Population Size

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Date

1977

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Abstract

The effect of random mixing of marked and unmarked fish on the accuracy of a Petersen population size estmate was investigated. By comparing the ratio of marked and unmarked fish in a sample catch at different points in time, the effect of random mixing was observed. Three species of Centrarchids, Micropterus salmoides, Lepomis macrochirus, and Lepomis gulosus in a small central Texas pond were studied. The ratios for all three fish, called the R/C ratio, had a characteristic pattern. From an initially high value, the ratio dropped off through time to a more stable position indicating that the accuracy of the population size estimates was very subject to the amount of time from initial marking to recapture or the amount of time allowed for random mixing of marked fish to take place. With short time intervals such as 10 days, the population size of fish in the pond was seriously underestimated. One hundred- twenty days was shown to be sufficient time to ensure total mixing of marked and unmarked fish and therefore not seriously affect the accuracy of the estimate. These results are applicable only to a fall census when growth is at a minimum.

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Program year: 1976-1977
Digitized from print original stored in HDR

Keywords

population size estimate, Centrarchids, Micropterus salmoides, Lepomis macrochirus, Lepomis gulosus, marked fish

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