Fig 4. Movement tracks of a yellowfin tuna by different geolocation methods.

(a) Geolocation estimates from light data (white x and line); light-based Kalman filtered track (yellow triangles and green line); UKF-SST track (red line). The white dot indicates the tag deployment location and the green dot indicates the tag pop-off location. (b) GA-OHC filtered track of the same fish. (c), The root-mean-square (RMS) error of OHC between the observed OHC _T and predicted OHC _M as a function of generation time. (d), Comparison of OHC values between UKF-SST and GA-OHC filtered tracks (black line is the OHC _T estimates from PSAT depth and temperature data; red line is OHC _M values at the location determined by the UKF-SST filtered track; and, purple dots are the OHC _M values at the location determined by the GA-OHC filtered track.