All The Missing Whales

Indications that there used to be a lot more of them:

Human pressure on whale stocks "was much earlier, much larger and much more significant than previously thought", environmental historian Poul Holm of the University of Dublin, Ireland, told a meeting of the Census on Marine Life (CML) project in 2009.

...So far, genetic evidence has received the most attention, in particular the publication of a controversial study in 2003 by Stephen Palumbi and Joe Roman of Stanford University's Hopkins Marine Station. This study's high numbers appeared to blow IWC historical estimates out of the water, particularly for humpback whales (Science, vol 301, p 508).

The pair had investigated whales for signs of genetic variation. Geneticists claim to be able to use this to estimate the size of the population in the past since large populations tend to accumulate diversity through random DNA mutations and breeding, while small populations lose it through inbreeding. The results were dramatic.

The IWC believed that before large-scale whaling began, the North Atlantic was home to about 20,000 humpback whales. With a current population of about 10,000 and rising, this meant that under the 54-per-cent rule hunting could soon resume. But Roman and Palumbi estimated the pre-exploitation population was more than 20 times as great, at 240,000. Globally, they suggested, there may have once been 1.5 million humpbacks, rather than the 100,000 estimated by the IWC.

...Palumbi and Roman are not alone, however. Charles Scott Baker, a conservation geneticist at Oregon State University in Newport, has used DNA analysis to investigate minke whales. IWC estimates put their number today near their historical levels of around 600,000 globally. But Scott Baker reckons that as recently as 300 years ago there were probably close to 1.5 million of them. That suggests its recovery is still at an early stage.

Can these conflicting numbers be reconciled? Historical abundance is estimated using a combination of the current population and the total historical catch. The problem is that nobody can be sure how many whales were taken in the past. Some estimate that the total catch for the 20th century was about 4 million. But official whaling records are incomplete, especially post-war logs.

The most dramatic revelations have come from the archives of the former Soviet Union, which carried out massive illegal harvesting of whales - especially in the 1950s and 1960s - while sending false logbook records to the IWC. Memoirs of Russian whaling inspectors published in the past two years reveal that from 1959 to 1961, Soviet whaling fleets killed 25,000 humpback whales in the Southern Ocean, while reporting a catch of just 2710. This continued well into the 1970s according to new revelations at an IWC conference in 2009 by one of the original whistle-blowers, Yuri Mikhalev of the South Ukrainian Pedagogical University in Odessa, Ukraine.

...There is also growing evidence of massive damage to whale populations inflicted by humans long before the industrial era of explosive harpoons and factory ships. Some 70,000 records of whale catches and sightings assembled by the History of Marine Animal Populations project, part of the CML, suggest the impact of pre-industrialised hunting on whale stocks was much greater than previously assumed.

Basque and Japanese fishermen were catching right whales 1000 years ago. And for centuries, many other island and coastal communities have harvested the creatures. Whaling was the first global industry, says marine biologist Callum Roberts of York University in the UK. Whalers were hunting deep in Arctic waters long before explorers showed up. When Darwin reached the Galapagos Islands in 1835, they were already overrun with American vessels pursuing sperm whales.

According to Robert Allen of the University of Oxford, it now appears that many whale populations in the northern hemisphere were ravaged in the 17th and 18th centuries by whalers employing hand-held harpoons and sheer manpower. Back then, whales were essentially "floating oil wells", providing oil for candles, street lamps and machinery, as well as ingredients for perfumes, plus bones for everything from corsets to fishing rods.

The downfall of the Arctic bowhead whale is the best documented. Thousands of Dutch whaling ships headed into the Arctic in the 17th and 18th centuries to catch bowheads off Spitsbergen, until the population collapsed. Whaling then moved to the waters off Greenland where a frenzied hunt soon wiped out what had been the biggest whaling ground in the world. Today there are only about 1000 bowheads swimming west of Greenland - and none at all between Greenland and Spitsbergen, says Allen.

The emerging history of pre-industrial whaling, and what it suggests about past whale numbers, raises some important questions. Not just about the wisdom of a return to commercial whaling, but also about ocean life in general. Jeremy Jackson of the Scripps Institution of Oceanography in San Diego says the hunting of whales has fundamentally reorganised ocean ecosystems. Today, ocean biomass is dominated by small creatures. But he says this "trophic pyramid", with only a tiny tip of large creatures, may not be natural. Before we intervened, he says, the pyramid was probably the other way up, with large beasts dominating the biomass.

Keeping these big beasts fed would be possible if the turnover of their smaller prey species was fast enough to ensure that fresh food was constantly being produced. And rather than devouring an ecosystem, a greater number of whales might help feed it: when a whale dies, its carcass sinks to the seabed where it could feed a local population of scavenging species for up to 80 years. Peter Karieva, chief scientist at conservation charity The Nature Conservancy in Seattle, Washington, says there is evidence that the decline of sperm whales in the tropical Pacific has moved the entire ecosystem towards domination by species like squid. We don't know what was lost with the whales - or what else might reappear if their numbers soared.

...Until now, says Jeremy Jackson, the widespread anecdotal evidence of huge numbers of whales and other large animals on the planet has been systematically downgraded by scientists simply because it cannot be proved. He calls the process "scary, unbridled anti-historical determinism". The result, he says, is that "we deny the once-great existence of anything we killed more than a century ago".