As concern grows about the health of the world’s oceans, threatened by rising temperatures, acidification and overfishing, a new report has claimed there is at least one reason to be optimistic about the future of the depths: the return of whale populations.
Scientists have previously suggested that whales are too rare and nomadic to have much of an impact on the wider marine ecosystem. However, a new study published in the journal Frontiers in Ecology and the Environment casts whales as “engineers” of the seas.
In the paper, researchers from the University of Vermont suggest that the 13 species of great whale have an important and positive influence on the function of oceans, on carbon storage, and on the state of fisheries around the world.
An ocean repopulated with whales would therefore be an ocean better prepared for the challenge of climate change.
“As humpbacks, grey whales, sperm whales and other cetaceans recover from centuries of overhunting, we are beginning to see that they also play an important role in the ocean”, said study author Joe Roman.
They do this, the paper suggests, primarily by spreading nutrients across the seas in their faeces.
In a slightly grim process known as “whale pump“, the huge mammals feed in the depths and releasing faecal plumes near the surface, providing food for plankton and boosting the productivity of threatened ecosystems. Due to the vast distances whales travel, these benefits are spread far and wide.
Though historically, fishermen have seen whales as competition, this means that bigger whale populations “could lead to higher rates of productivity in locations where whales aggregate to feed and give birth,” supporting stronger fisheries.
Even after death, whales continue to play an important role, the study suggests, as their carcasses store carbon on the bed of the deep-sea.
Though industrial-scale whaling left some whale species on the brink of extinction before the international 1986 ban, there are now encouraging signs that populations are recovering.
However, six species of great whale remain at risk of extinction, and some nations have been accused of using loopholes in the law to continue whaling operations.
Photo: Denis Hawkins via Flickr