Gray whale acoustic recordings and visual sightings. The top plot shows the modelled number of southbound gray whales that passed Granite Canyon each day based on visual sightings (circles, left axis) and the proportion of gray whales that were travelling south (dots, right axis). Yellow circles indicate days when visual observers were on-effort. Error bars show the 95% Credibility Interval of the modelled abundance estimates. The middle plot shows the corrected M3 call count in blue triangles (corrected based on probability of localization). The bottom plot shows the daily calling rate based on the number of M3 calls and the number of estimated whales for days when visual observers were on-effort. The solid line is the two-term power model with the dashed line showing the 95% non-simultaneous prediction interval for the calling rate function. The coefficients of the two-term power model are a = 1.22 × 1.0−6, b = 3.79, and c = 3.39. The error bars show the uncertainty in the calling rate based on the 95% Credibility Interval of daily gray whale abundance estimates.