In a study recently published in
Science magazine, "Whales Before Whaling in the North Atlantic," authors Joe Roman of Harvard University and Stephen Palumbi of Stanford University, both geneticists, suggest that some whale populations in the North Atlantic were once ten times greater than previously estimated.
The authors' genetic analysis of current populations of three species in the North Atlantic suggest that the historical records used to estimate whale populations, including whalers' logbooks, dramatically underestimate the original size of these populations. Palumbi and his former graduate student Roman determined that 240,000 humpback, 265,000 minke, and 360,000 fin whales once roamed the North Atlantic. Although some of the numbers are contested, it's estimated that there are now 10,000 humpback, 149,000 minke, and 56,000 fin in the North Atlantic.
This is relevant because historical records-based estimates have been used by the International Whaling Commission (IWC), the body that regulates whaling, to set recovery goals for depleted whale stocks. One of the recommendations that the IWC has proposed for the resumption of commercial whaling is that a species must be 54% of its historic population.
"If you believe the logbook numbers, then the populations of some whales will be up to exploitable levels before the next presidential election," Palumbi told The Los Angeles Times in late July. "If these genetic numbers are correct, we are far from succeeding at bringing them back close to the status of what they were in the past. It will take another 50 to 100 years of protection."
It is well known that, historically, whales were killed at alarming rates. However, it was not until the 1970s that IWC member governments were forced to confront the devastating effect that the whaling industry had had, and was having, on whale populations. By the 1980s, eight out of the ten targeted species of great whales had become commercially extinct. As a result of this decimation, the IWC adopted a commercial whaling moratorium in 1982 with the goal of restoring and conserving these whale populations.
Prior to the Roman-Palumbi study, whaling logbooks dating back to the mid-1800s were used as the basis for determining pre-industrial whaling numbers. These logbooks have never been viewed as completely accurate, yet they were the best source of information available at the time.
Logbooks are not fully reliable for a variety of reasons, including missed entries, lost logbooks, and deliberate under-reporting to avoid taxes. In addition, this methodology presumes that whaling was the sole source of massive removals from a whale population; yet, there may have been significant whale losses during the two World Wars and from other human-caused impacts. This new study marks the first attempt to use genetics, rather than written historical records, to confirm the number of whales that used to roam the seas before industrialized commercial whaling.
The study's results have generated much debate, from a wide variety of sources, from pro-whaling nations to scientists who question whether logbook-based numbers could be off by such wide margins. What's more, the study's analysis examined only one small unit of genetic material rather than several. The technique also depends on assuming a certain genetic mutation rate, which may or may not be accurate, and does not take into account any level of genetic contributions from distant populations. These limitations to the analysis may have resulted in an overestimation of original population numbers.
The researchers intend to take these critiques into account and continue to refine the methodology and its conclusions, but the debate they have generated with their initial results can only encourage improvement in historic population estimates.
The study could significantly impact the future of certain whale populations. For instance, using the old estimates, North Atlantic humpback whales have essentially reached the 54% threshold, which could potentially allow the IWC (subject to the adoption of a Revised Management Scheme) to declare the population open to hunting. (The historic population is estimated from logbooks at about 20,000 animals, or about twice the current population estimates.)
If Roman and Palumbi are correct, however, North Atlantic humpbacks are at barely 5% of their historic levels. At a minimum, this study demonstrates that our traditional understanding of "historic levels" is highly uncertain.
The truth of the matter is that no one knows for certain just how many whales existed prior to commercial whaling. What's more, we are not even sure how many whales exist now. Reason and logic dictate that in the face of such overwhelming uncertainty, any resumption of commercial whaling based upon traditional notions of "historic levels" would be irresponsible and detrimental to whale populations around the world.
