New Genetic Analysis of Antarctic Minke Whales Challenges “Krill Surplus Hypothesis”
20.01.2010 - Water & Oceans, Flora & Fauna, Antarctic
A new genetic analysis of Antarctic minke whales published this week in the journal Molecular Ecology suggests that these smaller whales have not benefited from excessive hunting of other larger whale species during the beginning and mid 20th century.
With large whale species such as blue, fin and humpback whales the over-hunted to the point of near extinction, a huge surplus of krill accrued, benefiting the remaining predators such as the minke whale. According to some scientists under what is known as the “Krill Surplus Hypothesis”, this allowed the numbers of minke whales to increase three to eight-fold, ultimately making it difficult for whale species hunter to near extinction to recover. This has led commercial whaling advocates arguing in favour culling minke whales to help other whale species’ numbers recover.
However the new study, which was conducted using 52 samples of whale meat taken from Japanese seafood markets, shows that this may not be the case. By amplifying and sequencing a large number of genes from the samples of whale meat, the researchers where able to estimate the historic range of population sizes necessary to produce and maintain the levels of genetic diversity found in the whales they tested.
They determined that the long-term Antarctic minke whales population to be about 670,000 individuals, a number close to the current estimate derived from sighting surveys. This led them to conclude that minke whales today have “a great deal of genetic diversity, which reflects a long history of large and relatively stable population size,” according to Scott Baker of Oregon State University, meaning that there has historically been enough krill to support large minke populations, thus refuting the ”Krill Surplus Hypothesis”.
