Orcas - Apex Predator of the Oceans

Great white sharks have a reputation for being one of the most intimidating apex predators in the ocean, but recent studies indicate that even great whites are afraid of killer whales!

In 2009, Salvador Jorgensen and his colleagues at the Monterey Bay Aquarium tagged 17 great whites off the coast of California. Great white sharks typically feed on young elephant seals in the area. When a pod of orcas entered the surrounding waters the sharks disappeared, and within 8 hours all had vanished. Most of them did not return for the rest of the elephant seal season (September-December). If the orcas are just passing through the area and not stopping to hunt, the number of seals hunted can drop nearly 62%, allowing a larger population of young seals to survive the season.

This seemed strange so the researchers extended their search to look at data from 165 great whites tagged between 2006 and 2013. They discovered a pattern – when orcas entered the area, all of the sharks immediately fled. Some return after a few months and others will not return for up to 1 year, even when the orcas are just passing through the area. It is thought that the sharks can smell the approaching orcas, even if they are never close enough to actually see them.

Why are great white sharks so afraid of orcas? Interactions between the two typically do not end well for the shark. In 1997 the first recorded interaction between a great white and orcas was documented. Two orcas killed a great white shark and ate its liver. Removing the liver and leaving the rest of the body is quite consistent behavior for orcas. In 2017, 5 great whites washed ashore in South Africa with similar signs. The livers had been removed with incredible precision and orcas are believed the most likely culprit.

Orcas are highly intelligent and work in groups when they hunt. Their very presence, even when brief, can have a huge impact on the surrounding ecosystem. When the great white sharks flee and do not hunt in an area for up to a year, the numbers of their prey do not decline as they normally would, which affects other areas of the ecosystem in turn. It is always exciting and fascinating to learn more about the oceans and their inhabitants. It seems that orca whales can be considered the true apex predator of the ocean now!

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