Isotopic and genetic evidence for site fidelity to feeding grounds in southern right whales (Eubalaena australis)

VALENZUELA, LUCIANO O; SIRONI, MARIANO; ROWNTREE, VICTORIA; CALLIARI, DANILO; SEGER, JON

Conferencia; The 6th International Conference on Applications of Stable Isotope Techniques to Ecological Studies; 2008

Premio a la mejor presentación oral.  Ocean warming will certainly affect the migratory patterns of many marine species, but specific changes can be predicted only where behavioural mechanisms guiding migration are understood. Southern right whales show maternally inherited site fidelity to near-shore winter nursery grounds, but exactly where they go to feed in summer remains mysterious. They consume huge quantities of copepods and krill, and their reproductive rates respond to fluctuations in krill abundance linked to El Niño-Southern Oscillation (Leaper et al., 2006, Biol. Lett. 2:289 292). Here we show that genetic and isotopic data, analysed together, indicate maternally directed site fidelity to diverse summer feeding grounds for female right whales calving at Península Valdés, Argentina. Isotope values from 131 skin samples span a broad range (δ13C = -23.1 to -17.2 , δ15N = 6.0 to 13.8 ) and overlap with isotope values (from the literature and unpublished) of krill and copepods from a large geographic range; from waters north of the Polar Front, to the southern Patagonian shelf, to offshore Uruguay. The isotope values of skin samples are more similar than expected among individuals sharing the same mitochondrial haplotype, indicating that whales learn summer feeding locations from their mothers, and that the time scale of culturally inherited site fidelity to feeding grounds is at least several generations. Such fidelity would be expected to limit the exploration of new feeding opportunities, and might explain why this population shows increased rates of reproductive failure in years following sea surface temperature anomalies in the southwestern South Atlantic, the richest known feeding ground for baleen whales.