Depletion sampling in stream ecosystems: assumptions and techniques

Reliable fish and invertebrate population estimates depend on meeting the assumptions of the methods used for organism capture and data analysis. A review of several population estimation studies has indicated that assumptions of the removal method for population estimation are often violated. This paper outlines (1) procedures to assist in meeting the removal method assumptions (2) an economical procedure to obtain reliable invertebrate population estimates by the removal method and (3) a computer program (CAPTURE) designed to test the adequacy of study design and to analyze capture data where variable probability of removal exists.