This record represents fin whale sound production detected from raw passive acoustic data. The Low Frequency Detection and Classification System (LFDCS) call library for fin whale 20-Hz pulses was built for the data sampled at 120 Hz. All fin whale detections with a Mahalanobis distance of 3.0 or less were manually verified for true detections. A logistic regression was applied to these results to facilitate reducing the size of the dataset that ultimately needed to be manually verified for confident species detection. This analysis revealed that a minimum number of 29 detections per time window used (hour or day) need to be detected to ensure that a fin whale was truly detected with a confidence of 90%. All days with at least 29 detections were manually verified for daily presence of fin whale 20-Hz pulses. From days with 29 or more detections, fin whales were considered present for that day if a true detection was found within a regular inter-pulse interval pattern of at least three other 20-Hz pulses. These data were recorded at SanctSound site SB01_02 between January 28, 2019 and April 2, 2019.