PMC6802580_01
Correlations among simulated delta13C from the top 10% best fitting migratory movement models (grey lines, right hand y-axis) and delta13C from baleen (black line, left hand y-axis; see Fig. 2).. Simulated delta13C values are six month moving average values for the time series of simulated plankton delta13C values in that location, reflecting temporal integration of phytoplankton delta13C values within the food chain before ingestion by the whale as krill. The end points of the simulations and empirical data have been aligned to coincide.
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fig-1
We then compared the simulated stable isotope profiles (Fig. 1) to the profile measured in the blue whale baleen (Fig. 2) with simple linear regressions.
Variation in stable isotope values in the NHM blue whale, expressed as delta13C (black circles, left y-axis) and delta15N (grey circles, right y-axis).. Samples were taken longitudinally through the baleen plate (n = 97 samples from a single baleen plate for both isotopes). There is strong annual periodicity and cross-correlation (Figs. S2 and S5) in both isotopes. The approximate relationship to years assuming a growth rate of 13.5 cm y-1 is shown on the upper x-axis, and year boundaries are indicated by vertical dotted grey lines. Phases are the three behavioural phases defined in the text.
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fig-2
Simulated locations of the whale taken from the top 10% best fitting migratory movement models.. Colours reflect the behavioural phase. Phase one is early 1884 to spring 1886, phase two is summer 1886 to spring 1890, and phase three is spring 1890 to spring 1891.
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fig-3
S1 and Fig. S3).
Simulated locations by month taken from the top 10% best fitting migratory movement models for behavioural phase two (summer 1886-spring 1890) only.
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fig-4
West Ireland, Canaries/Azores and Mid Atlantic Ridge, and the Cape Verde/Mauritanian upwelling area; Fig. S4); and (b) seasonal migration between high latitudes and subtropical latitudes. Within each movement hypothesis simulation, individual whales were parameterized with random variation in their maximum daily movement, providing a range of behaviours; a larger range of maximum daily movement was introduced in migratory whales.