Fig 1.
Photo Credit: D. Krause/NOAA.
Table 1.
Photogrammetric (P) and manual (M) measurements used in regression models.
Table 2.
Measurement accuracy comparisons.
Fig 2.
Example photos of leopard seal body positions and substrates.
A) A dorsal-straight body position on sand substrate. The ground reference scale is marked by two red crosses. B) A lateral-straight body position, C) a dorsal-curved body position, and D) a lateral-curved body position.
Fig 3.
An example measured leopard seal with labeled photogrammetric measurements.
Fig 4.
Photogrammetrically-derived measurements of leopard seal overall length (n = 50) compared between three independent observers (ANOVA F2,147 = 2.009, p = 0.138).
Fig 5.
Aerial versus ground precision.
Observer-derived variances compared between ground-based SL (n = 9) and aerial PSL (n = 9) measurements. Residuals were calculated by summing the absolute difference between each measurement and the mean value for a given animal. Leven’s Test F1,9 = 2.439, p = 0.14.
Table 3.
Comparison table of the most informative model from each model family.
Fig 6.
Linear mass estimation models per observer.
Linear regressions of overall length (POL) times umbilicus width (PUW) to leopard seal mass with 95% confidence intervals (gray ribbon) for each observer. For all models n = 15, R2 > 0.85, and P << 0.0001.
Table 4.
A summary of pinniped mass estimation studies.