We predict that Antarctic blue, southern right and fin whales will be at less than half their pre-exploitation numbers by 2100 because of slow growth rates and heavy historical whaling.
Blue whales are currently at around 1% of pre-whaling numbers.
Vågane whaling station in the Early 19th century. Photo: Wikipedia Commons.
One species that has bounced back relatively well after whaling stopped in the late 20th century is the humpback. More than 200,000 humpback whales were harvested from Southern Hemisphere waters since the late 18th century. Today their population is estimated to be about a third of the size it was prior to the days of industrial-scale whale harvests. While that might seem low, by 2050 we could expect the population to have recovered completely, which is good news for whale watchers along the Australian coastline.
The story is not so positive for the southern right whale (so named because this species was easy to catch with high commercial potential so was regarded as the ‘right’ whale to hunt).
We estimate that southern right whales globally remain at less than 11% of their pre-whaling numbers. This species was heavily whaled in the 1800s to the point where there were only 300 left in the world by the 1920s. Then they were hit again in the 1960s and 70s by illegal Soviet whaling. Combine this with their slower reproductive rates and the outcome is for a slower recovery.
This is the first time a complex ecosystem model that includes ocean physics and climate change has been used to predict future whale numbers, and this research helps answer some of the uncertainties regarding their recovery. Population estimates and plausible future predicted trajectories for Southern Hemisphere baleen whales are basic requirements for management and conservation.
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Reference: Tulloch VJD, ÉE Plagányi, R Matear, CJ Brown & AJ Richardson (2017). Ecosystem modelling to quantify the impact of historical whaling on Southern Hemisphere baleen whales. Fish Fish 00:1–21. https://doi.org/10.1111/faf.12241