#Greater Farallones National Marine Sanctuary

[montereybayaquarium]

Happy National Marine Sanctuary Day! 🌊🎉

Today, we celebrate our protected waters throughout the U.S., including the ocean and the Great Lakes.

We have even more to sea-lebrate this year as we look forward to the official designation of the Chumash Heritage National Marine Sanctuary on California’s Central Coast. 

Once final, 4,500 square miles of coastal waters from Morro Bay to the Channel Islands will receive important protections to help safeguard its ecological, historical, and cultural ocean resources. It will become California’s fifth national marine sanctuary, joining Monterey Bay, Cordell Bank, Greater Farallones, and Channel Islands national marine sanctuaries.

Learn more about this historic designation.

📸 Photo courtesy of @noaasanctuaries

[noaasanctuaries]

Meet Dr. Nancy Foster Scholar, Serina Moheed! Serina is a PhD student at the University of California, Davis studying host-pathogen relationships in marine coastal ecosystems. Join Serina as she brings us through a day in her life in Greater Farallones National Marine Sanctuary.

[bowsonmyblunts]

Mercenary

The dimly lit ceiling light burned a soft pink through your eyelids. You didn't want to wake up, not yet,

Your whole body bolted forward to the ice cold water that trickled down your body. You blinked at the shadow in front of you. Your handed down dark army green tactical vest drenched in water. "talk about rude awakening..." You grunted out squinting at the person in front of you; or more specifically people. "Whatever it is no. I'm not interested." You spit in a raspy voice looking down at your ashy black boots. Your hands shuffled against the burning ropes on your wrist.

"Come on Oliveria you haven't even heard what we had to say." Your eyes shot up venomously at the blue eyed women.

"Don't you fucking call me that Jill." Your voice was small but dangerous. Your eyes darted around the room: Rebecca Chamber, Chris Redfield, Claire Redfield. Jill opened her mouth to spit an insult at you but any irritation in her body left as she saw the gilt of Carlos in your eyes. You saw the way her eyes softened. You sighed and rested your arms on the top of your vest.

"Whaddaya want?" Chris's eyes widened and he swiftly brought his hand to his gun. Claire quickly grabbed at him and shook her head.

"We need help," She hands you a folder.

Twelve cases wherein people had died after being mysteriously infected by an advanced strain of the T-virus and were found with needle marks on their bodies.

Claire followed your eyes interrupting as you had gotten the gist of the operation.

"I discovered an orca infected with the same T-virus strain as the victims from Chris's case swimming near the Greater Farallones National Marine Sanctuary, which there had also happened to have been several missing whales." She handed you another folder; this containing photographs. Your face remained still as you looked over the grotesque imagery. Your eyes caught the name of an island.

"The victims had visited Alcatraz Island before they died..." You finally concluded. Jill nodded slowly and cautiously. She knew that if you refused they'd barely be a chance they would make it out alive without a serious amount of casualties. The tension around was thick. You stood up and dusted off your clothes.

"Alright let's do this, and maybe next time you could just tap me on the shoulder, thought I was gonna get tortured or something." You grinned walking through them and out the door.

SORRY I HAVEN'T POSTED just wanted to write down this idea sorry i know the beginning is a little shitty, I changed my idea

Another short story cos I have no motivation to write a full one. maybe part 2 with leon.

[rjzimmerman]

A Warning From a California Marine Heat Wave. (New York Times)

Excerpt from this New York Times story:

They call it “the Blob.”

A decade ago, sea surface temperatures in the Pacific shot up to 11 degrees Fahrenheit hotter than normal. A high pressure system parked over the ocean, and winds that churn cold, nutrient-rich water from the depths to the surface died down. Stagnant, warm water spread across the Northeast Pacific, in a marine heat wave that lasted for three years.

Under the surface, the food web broke down and ecosystems convulsed, at first unseen to humans on shore. But soon, clues washed up.

Dead Cassin’s auklets — small, dark gray seabirds — piled up on West Coast beaches. The auklets were followed by common murres, a slightly bigger black-and-white seabird. The carcasses were knee-deep in places, impossible to miss.

Researchers are still untangling the threads of what happened, and they caution against drawing universal conclusions from a single regional event. But the Blob fundamentally changed many scientists’ understanding of what climate change could do to life in the ocean; 10 years later, the disaster is one of our richest sources of information on what happens to marine life as the temperature rises.

And it is more relevant than ever. Last year, multiple “super-marine heat waves” blanketed parts of the ocean. Averaged together, global sea surface temperatures broke records, often by wide margins, for months in 2023 and 2024. As the climate warms, scientists expect extreme marine heat waves to become more frequent.

The Blob “was a window into what we might see in the future,” said Julia Parrish, a marine ecologist at the University of Washington who runs the Coastal Observation and Seabird Survey Team, a network of volunteers who survey beaches from Northern California to Alaska.

In a study published last year, Dr. Parrish and her colleagues estimate that the Blob eventually killed millions of seabirds, in waves of starvation.

More recently, researchers undertook a thorough post-mortem of the Blob in the Greater Farallones National Marine Sanctuary, off the California coast.

The sanctuary is one of 17 pockets of U.S. waters protected to varying degrees from development and industry. They are becoming test beds for ways people can try and help marine life — and the human livelihoods that depend on the ocean — adapt to climate change.

This summer, the National Oceanic and Atmospheric Administration published a “condition report” for the Greater Farallones, along with an accompanying climate vulnerability assessment that reveals just how shocking the Blob was for scientists.

The foundation species that creates habitat for everything else in the Greater Farallones is bull kelp, a seaweed that grows from the seafloor to the surface in dense forests. Before the Blob, Ms. Lipski and her colleagues hadn’t thought bull kelp would be particularly vulnerable to climate change.

By the time the Blob dissipated, more than 90 percent of Northern California’s kelp forests were gone.

Historically, kelp has had booms and busts, Ms. Lipski said. “We just thought that’s the pattern for kelp — it’ll recover,” she said. “And it hasn’t.”

Kelp is eaten by sea urchins, which are eaten by sea stars. During the Blob, a deadly disease spread among sea stars, causing urchin populations to explode. Urchins devoured the kelp, leaving behind a much more barren seascape to this day.

“Back in 2014, I think there was this feeling amongst our experts that relative to land ecosystems, the ocean is really resilient,” said Sara Hutto, the climate change coordinator for the Greater Farallones and Cordell Bank sanctuaries.

[nj-stone]

There's a whale in the San Francisco Bay right now, something never before seen in March https://www.sfgate.com/local/article/whale-is-in-the-San-Francisco-Bay-right-now-photos-16029835.php via @SFGate

[sciencespies]

Turns out there's another ocean creature that scares the hell out of great white sharks

https://sciencespies.com/nature/turns-out-theres-another-ocean-creature-that-scares-the-hell-out-of-great-white-sharks/

Turns out there's another ocean creature that scares the hell out of great white sharks

Just when you think orcas couldn’t possible be any more awesome, they get even better. A study in 2019 showed these whales are really good at scaring off the most feared beast in the sea. Yep. Orcas have toppled the great white shark off their ‘apex predator’ throne.

A team of marine scientists found that great white sharks (Carcharodon carcharias) will make themselves extremely scarce whenever they detect the presence of orcas (Orcinus orca).

“When confronted by orcas, white sharks will immediately vacate their preferred hunting ground and will not return for up to a year, even though the orcas are only passing through,” said marine ecologist Salvador Jorgensen of Monterey Bay Aquarium.

The team collected data from two sources: the comings and goings of 165 great white sharks GPS tagged between 2006 and 2013; and 27 years of population data of orcas, sharks and seals collected by Point Blue Conservation Science at Southeast Farallon Island off the coast of San Francisco.

The team also documented four encounters between great white sharks and orcas in the Greater Farallones National Marine Sanctuary, which they could then analyse against the other data.

The data revealed that whenever orcas showed up in the region – as in, every single time – the sharks made a swift exit, stage left, and stayed away until the next season. They would choof off within minutes, even when the orcas only hung around for less than an hour.

And there was a surprising beneficiary: the elephant seals (Mirounga angustirostrous) that inhabit the coastline and are preyed upon by the great white sharks.

“On average we document around 40 elephant seal predation events by white sharks at Southeast Farallon Island each season,” said marine biologist Scot Anderson of the Monterey Bay Aquarium. “After orcas show up, we don’t see a single shark and there are no more kills.”

Transient orcas have also been known to eat the elephant seals, but these visiting whales only show up infrequently. Resident killer whales feed on fish.

The sharks didn’t always go far. Sometimes they would only move a safe distance along the coast, where they were close to different elephant seal colonies. Sometimes, though, they would head out to the middle of the Pacific Ocean, the region dubbed the White Shark Café.

These are not tiny sharks, either. Some of them measure over 5.5 metres (18 feet) from nose to tail, and are probably pretty used to getting their own way wherever they go. But 5.5 metres is on the small side for orcas, which can prey on whales much larger than that, so they’re unlikely to be pushed around easily.

In addition, orcas have been observed preying on great white sharks around the world, including near the Farallon Islands. It’s still a little unclear why, but the orca-killed sharks that wash ashore (one is pictured at the top of the page) are missing their livers – their delicious, oil-rich, full-of-vitamins livers.

Whether the sharks are instinctively avoiding the predators that can so handily eviscerate them, however, or whether transients in the past have bullied the sharks away from the elephant seal food source is still an unknown.

“I think this demonstrates how food chains are not always linear,” Jorgensen said.

“So-called lateral interactions between top predators are fairly well known on land but are much harder to document in the ocean. And because this one happens so infrequently, it may take us a while longer to fully understand the dynamics.”

The research was published in the journal Scientific Reports.

A version of this article was first published in April 2019.

#Nature

[hudsonespie]

Clean Marine Program Awards Shipping Companies for Slowing Speeds

The Protecting Blue Whales and Blue Skies program recognized 16 global shipping companies for reducing speeds to 10 knots or less in the San Francisco Bay Area and the Southern California Region in 2020. 

The voluntary program is an initiative to cut air pollution, protect endangered whales, and reduce underwater noise. The 2020 program ran from May 15, 2020 through November 15, 2020. 

Awards

Three award tiers and financial incentives recognize participating companies, based on the percent of distance their fleet traveled through the Vessel Speed Reduction (VSR) zones at speeds of 10 knots or less. Credit was only given if the average speed of a transit through an entire VSR Zone did not exceed 12 knots.

“We are delighted to be able to set an industry example by voluntarily reducing vessel speeds in areas where endangered whale species regularly feed, helping us improve the way we do business, while continuing to deeply care for our environment,” said Stanley Kwiaton, MSC General Manager of Port Operations - West Coast.

MSC, Hapag-Lloyd, Yang Ming, and MOL ACE notably achieved the Sapphire tier in the large company category (greater than 30 transits) by slowing down more than 800 transits, combined. Swire Shipping achieved the Sapphire tier in the small company category (less than 30 transits). For their outstanding commitment, all five of these companies earned the Protecting Blue Whales and Blue Skies Whale Tail award. 

“Biodiversity is an integral part of our sustainability strategy,” said Wolfram Guntermann, Director Regulatory Affairs & Sustainability at Hapag-Lloyd, calling the program a “remarkable initiative.” 

Seven companies – COSCO Shipping Lines, Evergreen, GALI, “K” Line, Maersk, Wallenius Wilhelmsen, and Swire Shipping – generously declined their financial incentive payment. Those funds will be reinvested in the 2021 program.

The 10-knot target follows the National Oceanic and Atmospheric Administration’s (NOAA) and the United States Coast Guard’s request for all vessels (300 gross tons or larger) to slow down during the months of peak blue, humpback, and fin whale abundance to protect these endangered whales from deadly ship strikes.

Ship strikes continue to be a global threat to all large whale populations. Reducing fatal ship strikes is a major priority of NOAA’s, especially in NOAA’s West Coast national marine sanctuaries.

“One of Yang Ming’s priorities has been promoting the sustainability of the ocean and coastal environments,” said Leo Chiang, Vice President of Marine Operations. “That is why we take immense pride in being a volunteer in the Blue Whales and Blue Skies Program.”

Ocean-going vessels transiting the California coast generate nitrogen oxides (NOx, a precursor to smog), sulfur oxides (SOx), particle pollution, and greenhouse gases. These vessels account for more than 200 tons of NOx per day emitted off the coast of California, which affects ozone levels onshore in many regions of the state. 

The VSR incentive program has expanded in scope and environmental benefits each year, including 2020, which marked the sixth year. The 2021 program began on May 15, 2021, and runs through November 15, 2021. Eighteen companies are currently enrolled in the 2021 program.

The Protecting Blue Whales and Blue Skies program is a collaborative effort by Santa Barbara County Air Pollution Control District; Ventura County Air Pollution Control District; Bay Area Air Quality Management District; Channel Islands, Greater Farallones, and Cordell Bank national marine sanctuaries; The Volgenau Foundation; California Marine Sanctuary Foundation; Greater Farallones Association; National Marine Sanctuary Foundation; and Environmental Defense Center.

from Storage Containers https://maritime-executive.com/article/clean-marine-program-awards-shipping-companies-for-slowing-speeds via http://www.rssmix.com/

[sharkstewards]

Celebrating and saving sharks at Virtual Sharktoberfest 2020 with Shark Stewards, the Greater Farallones National Marine Sanctuary #whiteshark, #savesharks

[noaasanctuaries]

🥁 Drum roll, please! 🥁

We would like to introduce you to the winners of the 2023 Get Into Your Sanctuary Photo Contest.

Sanctuary Life

1st: Douglas Hoffman in Hawaiian Islands Humpback Whale National Marine Sanctuary

2nd: Jean Zuo in Monterey Bay National Marine Sanctuary

3rd: Douglas Croft in Greater Farallones National Marine Sanctuary

Sanctuary Recreation

1st: Chuck Graham in Channel Islands National Marine Sanctuary

2nd: Daniel Eidsmoe in Florida Keys National Marine Sanctuary

3rd: Bryan Dort in Thunder Bay National Marine Sanctuary

Sanctuary Views

1st: Bruce Sudweeks in Monterey Bay National Marine Sanctuary

2nd: Martin McClure in Greater Farallones National Marine Sanctuary

3rd: Courtney Stanford in Olympic Coast National Marine Sanctuary

Sanctuaries at Home

1st: Laurie Santoro

2nd: Tina Morrison

3rd: Jenn Fletcher

Sanctuaries Around the World

1st: María Rodríguez-Salinas

2nd: Lawrence Alex Wu

3rd: Kayvon Malek

Congratulations to all the outstanding photographers who entered our 2023 Get Into Your Sanctuary Photo Contest. Don’t forget to check out the winners and honorable mentions on our results page:

Stay tuned over the next few weeks as we feature each winner in our #EarthIsBlue campaign!

[dayapart]

Rewatering

Mono Lake is being rewatered. Saline lakes are on the decline globally because of water diversions. https://en.wikipedia.org/wiki/Mono_Lake

From the 30-year example of rewatering Mono Lake, it is clear that the rivers and aquifers of the Central Valley (California) can be rewatered. https://en.wikipedia.org/wiki/Central_Valley_%28California%29

Rewatering the Central Valley rivers and aquifers will increase the water flow through the Sacramento-San Joaquin Delta, San Francisco Bay and to offshore marine sancturaries such as Greater Farallones National Marine Sanctuary and managed fisheries such as at Cordell Bank National Marine Sanctuary. https://farallones.noaa.gov/ https://en.wikipedia.org/wiki/Cordell_Bank_National_Marine_Sanctuary https://cordellbank.noaa.gov/visit/fishing.html

(via California_Terrain_Map.jpg (JPEG Image, 3000 × 2765 pixels) - Scaled (26%)) http://www.gelib.com/page/3

See also pinned map of selected locations. https://goo.gl/maps/Ga4egG4sMHSHPJiq8

[davitydave]

Marine Explorers Summer Camp (at NOAA's Greater Farallones National Marine Sanctuary) https://www.instagram.com/p/BzyDIrFBQLy/?igshid=1c1xqx6kx8365

[typhlonectes]

Tufted Puffin (Fratercula cirrhata), Greater Farallones National Marine Sanctuary, 30 miles off the coast of California, USA

photograph by Elizabeth Labunski / USFWS

[walksanfrancisco]

Walking San Francisco & Thinking Out Loud As I was heading to the Crissy Field parking lot behind the Warming Hut I noticed all the sailboats and had to stop. The star of this pic is Alcatraz but the terra cotta rooftop of the Greater Farallones National Marine Sanctuary Visitor Center on the Crissy Field Airfield adds a bunch of bright orange. The faded white building picks up the boat sails and the silver grey bay water but the big story in this picture is the "Blue Whale" statue on loan from the Monterey Bay Aquarium. Made from recycled plastic collected in California, the sculpture seeks to address the serious issue of plastic pollution threatening our oceans. #pollution #bluewhale #walksanfrancisco #walkingtours #seriouswalkers #tourguide #recycle #alwayssf #sanfrancitizens #sanfranciscosightseeing #sanfranciscotour #picoftheday https://www.instagram.com/p/BtKveWeA3NZ/?utm_source=ig_tumblr_share&igshid=bj8v4a8j9ga

[csnews]

Why gray whales may be starving to death along the California coast

Juan Carlos Guerrero - April 18, 2019

Even before three dead whales showed up in the Bay Area this week, whale watching organizers knew something was wrong during a recent trip to Baja California, Mexico. 

"When we got down there the entire story was the whales are late, the whales are late," said Chris Biertuempfel, California's Programs Manager for the Oceanic Society. Biertuempfel said scientists noticed whales were giving birth outside the San Ignacio Lagoon, the spot they usually go to breed. 

"Their journey this year seems to be taking them longer. The fact that they would get down to Baja and give birth outside of the lagoon, shows that they mistimed the migration.," said Biertuempfel, who has several theories of why that may be happening.

He speculates the receding Arctic ice cap may be forcing gray whales to go farther north find food. That means they must travel farther on their migration south to Baja, and if they did not eat enough, they may be simply running out of fatty energy reserves.  That view is shared by Mary Jane Schramm of the NOAA Greater Farallones National Marine Sanctuary. 

"Ordinarily we would see this healthy, very linear migration, not really stopping. Going all the way up to the Arctic," said Schramm as she points to a map of the Pacific Ocean to show the typical migration of gray whales once they give birth in Mexico. Schramm said gray whales don't usually come into the San Francisco Bay. If they do, that means something is wrong. 

"It's a desperate move. And it has us alarmed because we've seen this play out before and in 1999 and 2000 when we lost 30 percent of their population," said Schramm. Thousands of gray whales died in that period. They had recovered, but Schramm fears something similar may be happening again. The culprit could be climate change. Unlike humpback whales that eat fish along their migration, gray whales are bottom feeders. They eat mudbugs that feed on algae under the Arctic ice to build up their fat reserves and then use that energy for their long migration.

Gray whales have the longest migration of any mammal, between 8,500 to 12,000 miles. They rely on their fat reserves for energy, but if they had to travel farther north for food or did not eat enough for an extended journey, they could starve along the way. It's as if they are simply running out of gas. 

"They are really carefully budgeting their energy, but this trip is longer than they anticipated and so we are starting to see these malnourished individuals," said Biertuempfel. According to the National Oceanic Atmospheric Administration, 30 whales have turned up dead along the western United States, including two that washed up the same day in Pacifica and Richmond. Scientists from the Marine Mammal Center and California Academy of Sciences are performing a necropsy on the whales to find out the cause of death. The Oceanic Society offers gray whale watching trips from Half Moon Bay from January through April and then whale watching trips to the Farallon Islands from May to November. On every trip, the group has a photographer who will take pictures of the whales so that they can be identified and scientists can map their journey. The whales are not tagged with GPS devices. Instead, the photographs are run through a program that looks distinguishing features to identify a whale, similar to face recognition technology. 

The public can also upload their own whale photos at the website Happy Whale.

[kathleenseiber]

Seabird die-off ‘has no precedent’

Why did nearly one million common murres wash ashore dead from California to Alaska in 2015 and 2016? “The blob,” caused this seabird die-off, say researchers.

Although the common murre must eat about half of its body weight in prey each day, common murres are experts at catching the small “forage fish” they need to survive. Herring, sardines, anchovies, and even juvenile salmon are no match for a hungry murre.

“The magnitude and scale of this failure has no precedent.”

So the die-off was unprecedented—both for murres, and across all bird species worldwide. Scientists blame an unexpected squeeze on the ecosystem’s food supply, brought on by a severe and long-lasting marine heat wave known as “the blob.”

Their findings appear in the journal PLOS ONE.

“Think of it as a run on the grocery stores at the same time that the delivery trucks to the stores stopped coming so often,” explains second author Julia Parrish, professor in the University of Washington School of Aquatic and Fishery Sciences. “We believe that the smoking gun for common murres—beyond the marine heat wave itself—was an ecosystem squeeze: fewer forage fish and smaller prey in general, at the same time that competition from big fish predators like walleye, pollock, and Pacific cod greatly increased.”

Common murres washing onto beaches in the Homer, Alaska area were so abundant in early 2016 that COASST beach surveyors were forced to collect and photograph them in batches. (Credit: COASST via U. Washington)

Seabird die-off

Common murres nest in colonies along cliffs and rocky ledges overlooking the ocean. The adult birds, about one foot in length, are mostly black with white bellies, and can dive more than two football fields below the ocean’s surface in search of prey.

Warmer surface water temperatures off the Pacific coast—a phenomenon known as “the blob”—first occurred in the fall and winter of 2013, and persisted through 2014 and 2015. Warming increased with the arrival of a powerful El Niño in 2015-2016. A number of other species experienced mass die-offs during this period, including tufted puffins, Cassin’s auklets, sea lions, and baleen whales. But the common murre die-off was by far the largest any way you measure it.

From May 2015 to April 2016, about 62,000 murre carcasses were found on beaches from central California north through Alaska. Citizen scientists in Alaska monitoring long-term sites counted numbers that reached 1,000 times more than normal for their beaches. Scientists estimate that the actual number of deaths was likely close to one million, since only a fraction of birds that die will wash to shore, and only a fraction of those will be in places that people can access.

Many of the birds that died were breeding-age adults. With massive shifts in food availability, murre breeding colonies across the entire region failed to produce chicks for the years during and after the marine heat wave event, the researchers find.

“The magnitude and scale of this failure has no precedent,” says lead author John Piatt, a research biologist at the US Geological Survey’s Alaska Science Center and an affiliate professor in the University of Washington School of Aquatic and Fishery Sciences. “It was astonishing and alarming, and a red-flag warning about the tremendous impact sustained ocean warming can have on the marine ecosystem.”

Trouble in the food chain

From a review of fisheries studies conducted during the heat wave period, the research team concluded that persistent warm ocean temperatures associated with “the blob” increased the metabolism of cold-blooded organisms from zooplankton and small forage fish up through larger predatory fish like salmon and pollock. With predatory fish eating more than usual, the demand for food at the top of the food chain was unsustainable. As a result, the once-plentiful schools of forage fish that murres rely on became harder to find.

“Food demands of large commercial groundfish like cod, pollock, halibut, and hake were predicted to increase dramatically with the level of warming observed with the blob, and since they eat many of the same prey as murres, this competition likely compounded the food supply problem for murres, leading to mass mortality events from starvation,” Piatt says.

As the largest mass die-off of seabirds in recorded history, the common murre event may help explain the other die-offs that occurred during the northeast Pacific marine heat wave, and also serve as a warning for what could happen during future marine heat waves, the researchers say.

University of Washington scientists recently identified another marine heatwave forming off the Washington coast and up into the Gulf of Alaska.

“All of this—as with the Cassin’s auklet mass mortality and the tufted puffin mass mortality—demonstrates that a warmer ocean world is a very different environment and a very different coastal ecosystem for many marine species,” says Parrish, who is also the executive director of the Coastal Observation and Seabird Survey Team, known as COASST. “Seabirds, as highly visible members of that system, are bellwethers of that change.”

Additional coauthors are from the University of Washington, the US Geological Survey, the US Fish and Wildlife Service, Farallon Institute, International Bird Rescue, Humboldt State University, the National Park Service, NOAA Fisheries, Moss Landing Marine Laboratories, NOAA Greater Farallones National Marine Sanctuary, and Point Blue Conservation Science.

Funding for the work came from the USGS Ecosystems Mission Area, the North Pacific Research Board, the National Science Foundation, and the Washington Department of Fish and Wildlife.

Source: University of Washington

The post Seabird die-off ‘has no precedent’ appeared first on Futurity.

Seabird die-off ‘has no precedent’ published first on https://triviaqaweb.weebly.com/

[sciencespies]

There's one other ocean creature that scares the hell out of great white sharks

https://sciencespies.com/nature/theres-one-other-ocean-creature-that-scares-the-hell-out-of-great-white-sharks/

There's one other ocean creature that scares the hell out of great white sharks

Just when you think orcas couldn’t possible be any more awesome, they get even better. New evidence shows these whales are really good at scaring off the most feared beast in the sea. Yep. Orcas have toppled the great white shark off their ‘apex predator’ throne.

A team of marine scientists has found that great white sharks (Carcharodon carcharias) will make themselves extremely scarce whenever they detect the presence of orcas (Orcinus orca).

“When confronted by orcas, white sharks will immediately vacate their preferred hunting ground and will not return for up to a year, even though the orcas are only passing through,” said marine ecologist Salvador Jorgensen of Monterey Bay Aquarium.

The team collected data from two sources: the comings and goings of 165 great white sharks GPS tagged between 2006 and 2013; and 27 years of population data of orcas, sharks and seals collected by Point Blue Conservation Science at Southeast Farallon Island off the coast of San Francisco.

The team also documented four encounters between great white sharks and orcas in the Greater Farallones National Marine Sanctuary, which they could then analyse against the other data.

The data revealed that whenever orcas showed up in the region – as in, every single time – the sharks made a swift exit, stage left, and stayed away until the next season. They would choof off within minutes, even when the orcas only hung around for less than an hour.

And there was a surprising beneficiary: the elephant seals (Mirounga angustirostrous) that inhabit the coastline and are preyed upon by the great white sharks.

“On average we document around 40 elephant seal predation events by white sharks at Southeast Farallon Island each season,” said marine biologist Scot Anderson of the Monterey Bay Aquarium. “After orcas show up, we don’t see a single shark and there are no more kills.”

Transient orcas have also been known to eat the elephant seals, but these visiting whales only show up infrequently. Resident killer whales feed on fish.

The sharks didn’t always go far. Sometimes they would only move a safe distance along the coast, where they were close to different elephant seal colonies. Sometimes, though, they would head out to the middle of the Pacific Ocean, the region dubbed the White Shark Café.

These are not tiny sharks, either. Some of them measure over 5.5 metres (18 feet) from nose to tail, and are probably pretty used to getting their own way wherever they go. But 5.5 metres is on the small side for orcas, which can prey on whales much larger than that, so they’re unlikely to be pushed around easily.

In addition, orcas have been observed preying on great white sharks around the world, including near the Farallon Islands. It’s still a little unclear why, but the orca-killed sharks that wash ashore (one is pictured at the top of the page) are missing their livers – their delicious, oil-rich, full-of-vitamins livers.

Whether the sharks are instinctively avoiding the predators that can so handily eviscerate them, however, or whether transients in the past have bullied the sharks away from the elephant seal food source is still an unknown.

“I think this demonstrates how food chains are not always linear,” Jorgensen said.

“So-called lateral interactions between top predators are fairly well known on land but are much harder to document in the ocean. And because this one happens so infrequently, it may take us a while longer to fully understand the dynamics.”

The research has been published in the journal Scientific Reports.

A version of this article was first published in April 2019.

#Nature