A Modified Folsom Plankton Splitter For Analysis Of Meter Net Samples

The large number of meter net samples needed to determine the spawning success of various species of fish in Canton Reservoir, Oklahoma, made subsampling advantageous. The basic Folsom plankton splitter was enlarged and modified so that meter net samples with volumes up,to 4,000 m\\. could be split into IO approximately equal subsamples. The splitter was constructed from a 12 inch diameter Plexiglas2 cylinder. Construction was accomplished using common shop tools. Chi-square tests (0.05 level) showed that there were no significant differences between the observed subsample counts and the expected counts. A nonparametric sign test showed that each chamber did not consistently have higher or lower counts than any other chamber. The minimum total number of organisms per sample that could be subsampled yielding estimates of the total sample number with less than a IO percent error 95 percent of the time were determined for larval gizzard shad and larval Chaoborinae. Determination of the minimum number of organisms per sample needed for subsampling other organisms can be completed as necessary.

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