Warning: El Niño forces sharks and snakes to land

 

Boel Holm/TT

 

Published 07.30

 

The number of young great white sharks off the coast of California is increasing dramatically. Archive photo. Photo: AP/TT

Lots of young great white sharks are expected to arrive on the California coast as the weather phenomenon El Niño grows stronger, and scientists warn of a “shark summer”. The sharks are not coming alone – the warm water from the south also brings rays and poisonous sea snakes with them.

Normally, colder, nutrient-rich water flows from the depths up into the California Current. It supplies nutrients that fish, kelp forests and other marine life depend on. But the process can be reversed by El Niño and the supply of zooplankton, small fish and other prey is cut off.

“We are getting a completely different ocean,” says Chris Lowe, professor of marine biology and director of the Shark Lab at Long Beach State University, to USA Today.

Must Adapt

Shark Lab is now warning fishermen, surfers and others that they may have to share the ocean with animals they are not used to. And that they may have to adapt for their own safety.

Both tiger sharks and bull sharks have been caught off the coast of California during previous El Niño events. Hammerheads that follow goldfish can be more aggressive when hunting, Lowe says.

During the 2015-2016 El Niño, two hammerhead shark bites were reported offshore. This year, with the marine heat wave and the rapidly growing El Niño phenomenon, scientists expect to see more such incidents.

One of the most dramatic changes off the coast of California involves great white sharks, mainly large numbers of juveniles, who follow the warmer waters. The phenomenon has been known for a long time. In 2015, when El Niño was also strong, there was a buildup of warm water offshore and the number of juvenile great whites doubled.

Stingray injuries

But the increase in great white sharks is not necessarily a danger to swimmers. A bigger concern is the stingrays – a favorite food of young sharks. Today, lifeguards in California already treat around 10,000 such injuries a year, and Chris Lowe fears that the number of injuries will skyrocket.

Another unwelcome guest is the extremely poisonous yellow-bellied sea snake, which only appears during unusually warm periods.

Now, scientists are growing concerned about the long-term effects of the warming waters associated with the El Niño phenomenon. Douglas McCauley, director of the Benioff Ocean Initiative, speaks of a double whammy as El Niño adds additional heat to the already existing heat wave and climate change.

“It’s going to be a strange and interesting fall and winter. I can tell you it’s not going to be normal. We’re following all aspects of the ocean with great interest, including the sharks.”

Facts

El Niño

El Niño and La Niña are phases of the El Niño-Southern Oscillation (ENSO) weather cycle. El Niño warms the surface waters of the eastern Pacific Ocean, while La Niña cools them.

El Niño occurs on average every two to seven years and usually lasts nine to twelve months. It often peaks around Christmas, hence the name El Niño (the boy child).

El Niño effects such as increased precipitation typically affect parts of southern South America, the southern United States, the Horn of Africa, and Central Asia, while severe drought can occur over Australia, Indonesia, and parts of southern Asia.

The 2023–2024 El Niño is reported to be one of the five strongest ever recorded.

Source: WMO, SMHI, NOAA