A new hydroacoustic data processor using a PDP 11/45 computer was developed and applied to some herring studies in southeastern Alaska. The new processor allows for analysis of up to 50 different depth intervals, has a threshold to eliminate noise, and has greater dynamic range than any previous hydroacoustic data processor. The new system was used to analyze some data previously recorded on analog magnetic tape, including a series of 20 replicate hydroacoustic surveys over a 4-day period in Carroll Inlet. Comparisons were made with an earlier model digital integrator and with results of oscilloscope (CRT) measurements. Results of replicate surveys and comparisons between different areas demonstrated that the distributional characteristics of the herring can greatly affect the results of hydroacoustic surveys. Key words: hydroacoustic, herring, Alaska, echo integration, digital processor, fish assessment