Natures wonders: massive sardine migration (Introduction)

by David Turell , Monday, September 20, 2021, 20:47 (947 days ago) @ David Turell

New studies:

https://www.sciencedaily.com/releases/2021/09/210915161346.htm

"Scientists have discovered how the Sardine Run, one of the world's biggest migration events, works. This spectacular event, considered the 'Greatest Shoal on Earth', involves the movement of hundreds of millions of sardines from their cool-temperate core range into the warmer subtropical waters of the Indian Ocean, on South Africa's east coast.

***

"This spectacular event, considered the "Greatest Shoal on Earth," involves the movement of hundreds of millions of sardines from their cool-temperate core range into the warmer subtropical waters of the Indian Ocean, on South Africa's east coast.

The sardine run is triggered by the upwelling of cold water on the southeast coast and as they swarm north they get sandwiched between the coast and a southward-flowing hot current that exceeds the sardines physiological capacity. They are then predated by huge numbers of dolphins, sharks, seabirds and even whales, an event that has featured in many nature documentaries. (my bold)

***

"'Surprisingly, we also discovered that sardines participating in the migration run are primarily of Atlantic origin and prefer colder water," says Professor Luciano Beheregaray at the Flinders University Molecular Ecology Lab, one of the study authors.

"'The cold water of the brief upwelling periods attracts the west coast sardines, which are not adapted to the warmer Indian Ocean habitat," says author Professor Peter Teske from Johannesburg.

"'This is a rare finding in nature, since there are no obvious fitness benefits for the migration, so why do they do it? "We think the sardine migration might be a relic of spawning behaviour dating back to the glacial period. What is now subtropical Indian Ocean habitat was then an important sardine nursery area with cold waters," says Professor Teske.

"This visually breathtaking migration run attracts tourists from around the world who are keen to get a glimpse of the underwater spectacle...."

Comment: Another instinctual event that helps feed many other organisms. Note my bold. Evolution is not just about new forms but creating a food supply for all.