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4 - Crappie Population Assessment


Developing appropriate objectives for population parameters combined with standardized sampling procedures are vital to achieving effective fisheries management (Anderson, 1975). In the last few years, considerable attention has been given to the use of structural indices to describe and classify population structure.

Colvin and Vasey (1986) developed a method of assessing white crappiei populations in Missouri based on fall trap netting. Their system is based on standard point values assigned to estimates of density, growth (length-at-age), age structure, size structure, and recruitment calculated from fall trap net samples. A 0-10 rating is assigned to each of the five population parameters. The five scores are then summed to give an overall index of population condition. This assessment is currently used to evaluate crappie population structures in Missouri (M. Colvin, Missouri Department of Conservation, personnel communication).

A primary objective of the Crappie Management Plan was to develop a stock assessment index to evaluate crappie populations in Arkansas (Table 2). Missouri’s Stock Assessment Index was selected as a model from which to begin. The Missouri index, however, was developed for large reservoirs and white crappie populations only.
Arkansas has both species of crappie existing in large impoundments as well as small lakes. Therefore, the Missouri Stock Assessment Index was adjusted to accommodate
for these differences. Trap net data collected between 1989-1993 from fifteen Arkansas lakes, which varied from oxbows to large Corps of Engineer impoundments, were used to generate the model.

Arkansas’ lakes contain mixed populations of white and black crappie that must be managed as a group for regulatory simplification and so are combined for stock
assessment. Values (1-10) are assigned for ranges of five population parameters (density, growth, age structure, size structure and recruitment) calculated from fall trap
net samples. Highest point values are assigned to optimum measurements of each parameter. Because crappie density values varied greatly among the fifteen lakes sampled, and recruitment values are sometimes a poor indicator of actual Age-0 abundance, these two parameters have been weighted disproportionally in the assessment. Pointi values assigned to each population parameter are summed to give an overall rating for the crappie population condition. However, the values of the individual parameters are more useful for management purposes than the final assessment value.

The Crappie Population Assessment (Table 2) should provide a standardized means for fisheries managers to make objective evaluations of population structure and population trends over time in specific lakes. The assessment can also be used to compare indices between similar lake types such as Bull Shoals and Norfork.

Information Provided by Arkansas Game and Fish Commission<

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A sudden increase in depth, often created by washes, small creek channels, canyons, pinnacles, and other submerged topographic features.

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