Robert F. Illyes

Measuring Fish and Recording Data in the Field and Laboratory: A Microcomputer Application

Abstract A portable microcomputer-based system is described that allows rapid measuring and recording on diskette of fish lengths and weights in the field or laboratory. A simple, rugged, electronic caliper utilizing a precision potentiometer permits lengths to be measured with the same accuracy as a measuring board marked in millimeters. Software was developed to control information from the caliper and from an electronic balance supplying individual weights via a serial port. The package, based on an Apple IIc, optionally runs on batteries for use in the field. No significant difference (P = 0.05) was observed between variances of fish length using the electronic caliper and a measuring board. Precisionof a 9.2-cm caliper, based on independent measurements of 36 fish by three persons, was ± 1.3 mm with 99% confidence, compared with ± 1.1 mm using a measuring board. The mean difference between fish measurements using the measuring board and electronic caliper was only 0.36 mm. Measurements of fish using ...