The humpback whale

Twice a year the best conservation news on the coast swims past in plain sight. The humpbacks of eastern Australia spend the southern summer feeding in the cold, krill-rich waters near Antarctica, then in winter migrate thousands of kilometres north along the Queensland coast to breed and calve in the warm tropics, streaming south again in spring — often with calves in tow — on one of the longest and most reliable animal migrations anywhere. Off the Sunshine Coast the procession runs close inshore. The land's gradient does not stop at the beach; it carries on down a relatively narrow continental shelf, and the coast's headlands push the migratory lane near enough to the rock that the "humpback highway" can be watched from a clifftop — one reason this stretch has become one of the region's finest wildlife spectacles.

What the humpback depends on is not a single food or a single place but a journey — a corridor connecting two worlds spread across a hemisphere: the Southern Ocean feeding grounds where it fattens, the tropical breeding grounds where it calves, and unbroken, unharried passage along the coast between them. That kind of dependence is the mirror image of the koala's or the acid frog's: where the specialist is undone by the loss of one narrow thing, the migrant is exposed along the whole length of its route, to entanglement, vessel strike, noise and a warming ocean. And within living memory it was undone by the simplest thing of all — being killed. The whaling station at Tangalooma, on nearby Moreton Island, took 6,277 humpbacks between 1952 and 1962 before the whales ran out and it closed, by which time the entire eastern-Australian population had been driven to a few hundred animals clinging on (Tangalooma records, 1952–1962).

Then it turned around. Protected from whaling from 1963, the population climbed decade on decade, back into the tens of thousands — recent assessments put it at roughly forty thousand, at or above its estimated pre-whaling level — and the highway off this coast is once again one of the densest gatherings of great whales on Earth (regional marine syntheses, e.g. McPhee 2017). Read as a dependence, the lesson is unusually clean. This animal did not need a clever intervention or a delicate habitat repair. It needed the one thing removed that had been removing it. A few hundred to forty thousand: you cannot argue with a graph like that, and it is worth remembering, on a coast where most of the news runs the other way, that recovery on this scale is possible when the single fatal pressure is simply lifted.