Historical baleen plates indicate that once abundant Antarctic blue and fin whales demonstrated distinct migratory and foraging strategies

Southern hemisphere blue (Balaenoptera musculus intermedia) and fin (Balaenoptera physalus) whales are the largest predators in the Southern Ocean, with similarities in morphology and distribution. Yet, understanding of their life history and foraging is limited due to current low abundances and limited ecological data. To address these gaps, historic Antarctic blue (n = 5) and fin (n = 5) whale baleen plates, collected in 1947–1948 and recently rediscovered in the Smithsonian National Museum of Natural History, were analyzed for bulk (δ13C and δ15N) stable isotopes. Regular oscillations in isotopic ratios, interpreted as annual cycles, revealed that baleen plates contain approximately six years (14.35 ± 1.20 cm yr–1) of life history data in blue whales and four years (16.52 ± 1.86 cm yr–1) in fin whales. Isotopic results suggest that: 1) in the 1940s, blue and fin whales fed at the same trophic level but in slightly different habitats, 2) fin whales appear to have had more regular annu..., , , # Historical baleen plates indicate that once abundant Antarctic blue and fin whales demonstrated distinct migratory and foraging strategies

[https://doi.org/10.5061/dryad.905qfttrt](https://doi.org/10.5061/dryad.905qfttrt)

## Description of the data and file structure

### Table 1.

Antarctic blue (*Balaenoptera musculus intermedia*) and fin (*Balaenoptera physalus*) whale baleen data. Metadata for each individual (museum record number, species, sex, reproductive status at time of death (pregnant or not), fetus sex and length (cm), body length (cm), capture location (latitude and longitude), capture date, whaling vessel) was derived from ship's logs from expeditions in the Southern Ocean. Laboratory data include lab ID, measurement lengths along the baleen plate (cm), and ẟ13C and ẟ15N values.

Location data has been adjusted to 0.1 decimal places for the safety of the animals.

## Access information

Metadata from whaling logs was derived from the Smithsonian National Museum of Natu...