Data shows white sharks leave hunting grounds when orcas show up

Shane McGlaun - Apr 19, 2019, 8:40 am CDT
0
Data shows white sharks leave hunting grounds when orcas show up

White sharks and orcas favorite prey is the same, both like to eat the elephant seal. Researchers from the Monterey Bay Aquarium and partner institutions have found that great white sharks may not be the most formidable predators in the ocean. The scientists found that when orcas confront white sharks, the sharks immediately leave the preferred hunting ground and may not return to the hunting ground for an entire year.

The scientists found that this vacating of hunting grounds by the sharks occurs even if the orcas are only passing through the area. The researchers documented four encounters between oracs and white sharks at marine sanctuaries off the coast of California. The encounters were taken from data on interactions using 165 white sharks tagged between 2006 and 2013 and 27 years of seal, orca, and shark surveys.

In all the cases the scientists examined, the white sharks fled the sanctuary when orcas arrived and didn’t return until the following season. When the orcas pushed the white sharks from the hunting grounds, the seal colonies in the area indirectly benefitted from the interaction. The researchers say that on average there are 40 elephant seal predation events by white sharks each year, but after orcas show up there are no more sharks and no more seal kills.

Data shows that in years where the white sharks left there are four to seven times fewer predation events on elephant seals. White sharks gather in the area the researchers were investigating each fall between September and December to hunt for young elephant seals. Transient orcas feed on the same seals but only show up occasionally at the sanctuary.

The team determined when white sharks and orcas were in the area at the same time using the tags on the sharks and records of orca sightings during the same time span. The team notes that the white sharks are enormous with some over 18-feet long.


Topics
Must Read Bits & Bytes