Table 2.
Comparison of our results to other works.
| Song type | Period studied | Frequency (Hz) | Decrease in % of 2000’s value/year |
|---|---|---|---|
| Northeast Pacific (a) | 1963–2008 | 21.9 to 15.2 | 0.91 |
| Southwest Pacific (a,d) | 1964–2013 | 25.3 to 17.5 | 0.81 |
| Northwest Pacific (a) | 1968–2001 | 23.0 to 17.9 | 0.86 |
| North Atlantic (a) | 1959–2004 | 23.0 to 17.6 | 0.66 |
| Southern Ocean (a,c,e,f) | 1995–2014 | 28.5 to 25.8 | 0.50 |
| North Indian (unit 2) (g) | 2002–2012 | 61.5 to 59.8 | 0.27 |
| North Indian (unit 3) (a,f,g) | 1984–2013 | 116 to 99.5 | 0.51 |
| Southeast Indian (unit 2) (b) | 2002–2010 | 72.5 to 69.5 | 0.51 |
| Southeast Indian (unit 3) (a) | 1993–2000 | 19.5 to 19.0 | 0.38 |
| West Indian (f) | 2007–2015 | 34.7 to 33.7 | 0.35 |
| Southeast Pacific 1 (unit B) | 1970–2014 | 23.1 to 19.3 | 0.43 |
| Southeast Pacific 1 (unit C) | 1970–2014 | 30.8 to 24.3 | 0.58 |
| Southeast Pacific 2 (unit C) | 1996–2017 | 25.8 to 23.6 | 0.44 |
| Southeast Pacific 2 (unit D) | 1996–2017 | 25.8 to 23.5 | 0.45 |