Worldwide decline in tonal frequencies of blue whale songs

evidence

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).

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