**Fig. (1)**
Errors in the estimation of the day (peak day) when annual abundance of soft shell crabs is the highest by the SCPUE model (1), the Hierarchical model (2), and the Generalized additive model (3). Five hundred data sets are obtained for each of the seven survey schemes with four different number of survey years. The red dot denotes the median over the five hundred estimates, and the two red bars and two blue dots indicate 5th and 95th percentiles and 25th and 75th percentiles, respectively.