A Prototype Device for Subdividing Large Catches of Small Fish

When time and financial constraints do not permit counting of large catches of small fish, it is often necessary to divide the sample and estimate the total catch from a subsample.  Subsamples that are representative of the entire sample can be difficult to obtain due to human bias or rough field conditions.  We present a prototype for subdividing large catches of small (between 30 mm and 110 mm) fish that is inexpensive, easy to build, and provides unbiased and representative subsamples.  The device features a hopper that is tapered to a removable bottom that allows the researcher to control the speed and timing of the division.   Unbiased samples may be obtained under rough field conditions as the platform of the device is comparatively stable.  The device can easily be modified to accommodate different fish sizes and volumes of sample.  We provide an example of the performance of the device using a sample containing a known number of four species of fish.  Use of this apparatus, or one similar, in large-scale fish surveys would provide a convenient, objective, and more standard methodology.