[en] The SURPH program is a valuable tool for estimating survivals and capture probabilities of fish outmigrations on the Snake and Columbia Rivers. Using special data files, SURPH computes reach to reach statistics for any release group passing a system of detection sites. Because the data must be recorded for individual fish, PIT tag data is best suited for use as input. However, PIT tag data as available from PTAGIS comes in a form that is not ready for use as SURPH input. SURPH requires a capture history for each fish. A capture history consists of a series of fields, one for each detection site, that has a code for whether the fish was detected and returned to the river, detected and removed, or not detected. For the PTAGIS data to be usable by SURPH it must be pre-processed. The data must be condensed down to one line per fish with the relevant detection information from the PTAGIS file represented compactly on each line. In addition, the PTAGIS data file coil information must be passed through a series of logic algorithms to determine whether or not a fish is returned to the river after detection. Program CaptHist was developed to properly pre-process the PTAGIS data files for input to program SURPH. This utility takes PTAGIS data files as input and creates a SURPH data file as well as other output including travel time records, detection date records, and a data error file. CaptHist allows a user to download PTAGIS files and easily process the data for use with SURPH