System and collection settings
It is essential to document all initial echosounder parameter settings and any changes made to them during data collection. Record the old and new values, date, and time of modification so that the data collected prior to the modification can be reprocessed using a post-processing software package. A datasheet (example Fig. 17) should also include information on personnel and environmental conditions. The number of settings that can be changed in the field vary between Simrad and Biosonics units. Both units have collection settings that cannot be modified during analysis, and a number of other settings that can be modified if raw data is collected. If multiple surface units and/or transducers are available, the serial number of the unit(s) being used should be recorded.