Site fidelity to feeding grounds in southern right whales (Eubalaena australis) revealed by combined isotopic and genetic evidence

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

Quebec

Conferencia; 18th Biennial Conference on the Biology of Marine Mammals; 2009

Ocean warming will certainly affect the migratory patterns of many marinespecies, but specific changes can be predicted only where behavioralmechanisms guiding migration are understood. Southern right whales showmaternally inherited site fidelity to near-shore winter nursery grounds, butexactly where they go to feed in summer remains mysterious. They consumehuge quantities of copepods and krill, and their reproductive rates respond tofluctuations in krill abundance linked to El Niño-Southern Oscillation. Herewe show that isotopic and genetic data, analyzed together, indicatematernally directed site fidelity to diverse summer feeding grounds for rightwhales calving at Península Valdés, Argentina. Isotope values from 131 skinsamples span a broad range (δ13C = -23.1 to -17.2 , δ15N = 6.0 to 13.8 )and overlap with isotope values of krill and copepods from a largegeographic range, indicating a wide array of putative feeding locations; fromwaters north of the Polar Front, to the southern Patagonian shelf, to offshoreUruguay. The isotope values of skin samples are more similar than expectedamong individuals sharing the same mitochondrial haplotype, indicating thatwhales learn summer feeding locations from their mothers, and that the timescale of culturally inherited site fidelity to feeding grounds is at least severalgenerations. Such fidelity would be expected to limit the exploration of newfeeding opportunities, and might explain why this population showsincreased rates of reproductive failure in years following sea surfacetemperature anomalies in the south-western South Atlantic, the richest knownfeeding ground for baleen whales.