By comparing it with other grey whale populations, they found that this individual, a male, was probably born to the endangered western North Pacific population, found along the coast of eastern Asia. This means it travelled at least 20,000 kilometres to get to the southern Atlantic. Earth’s circumference is slightly over 40,000 kilometres. “This is the record really for an in-water migration, if you’re assuming that this individual started its life in the north-west Pacific and it found its way to Namibia,” says Hoelzel. “That’s as far as any vertebrate has ever gone in water, as far as we know.” Land dwelling mammals fall far short of this feat — the record is a grey wolf that roamed more than 7000 kilometres in a year.
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