Blue whale song frequencies are observed falling worldwide

Assembled from 32 blocks · 1 evidence · 38 related

1. Story
2. Analysis of acoustic recordings reaching back to the 1960s finds that blue whale song is being sung at steadily lower frequencies. The best-documented song type, off California, is reported as being sung 31 percent lower than in the 1960s, and seven of the ten known song types for which data exist are shifting downward, at different rates. Several explanations were floated in the 2009 paper that described it - changes in ocean acidity, whaling-driven shifts in average body size and population density, rising ambient noise - and none satisfied the authors. It is one of the few well-measured, long-running, genuinely unexplained observations in large-whale biology.
3. Knowledge
4. Blue Whale (Balaenoptera musculus)
5. Passive Acoustic Monitoring Arrays
6. Blue whale song frequencies are observed falling worldwide
7. Connections
8. Blue Whale (Balaenoptera musculus)
9. Passive Acoustic Monitoring Arrays
10. Antarctic Krill (Euphausia superba)
11. Rorqual Lunge Feeding
12. Antarctic Blue Whale (B. m. intermedia)
13. Pygmy Blue Whale (B. m. brevicauda)
14. Northern Indian Ocean Blue Whale (putative B. m. indica)
15. Fin Whale (Balaenoptera physalus)
16. Whale-Mediated Iron Recycling
17. Vessel Collision with Large Whales
18. The longest blue whale on record is measured at South Georgia
19. The heaviest blue whale on record is weighed
20. The IWC protects blue whales from commercial hunting
21. The commercial whaling moratorium takes effect
22. Blue whale song frequencies are observed falling worldwide
23. The energetics of blue whale lunge feeding are modelled
24. Baleen whale consumption is re-measured, and the krill paradox sharpens
25. Antarctic Summer Feeding Migration
26. IWC Southern Ocean Research Partnership
27. The 52 Hz call is identified in Navy hydrophone data
28. The SOSUS mission is declassified
29. Blue whale song frequencies are observed falling worldwide
30. Blue whales are found back at South Georgia
31. Evidence
32. Blue whale song tonal frequencies have declined worldwide since at least the 1960s; the best-documented type, off California, is now sung about 31 percent lower than in the 1960s, and seven of the ten known song types for which data exist are shifting downward at differing rates. Hypotheses considered by the authors - ocean acidity change, whaling-related shifts in body size and density, rising ocean noise - did not satisfy them. V55 verification basis: the substance was retrieved from secondary accounts describing this paper; the paper itself could not be fetched (int-res.com is blocked by this environment's egress proxy).