Sardines are small, schooling fish. Pacific sardines (Scientific name: Sardinops sagax caerulea) are blue-green on the back, with a white underbelly and white flanks with one to three sets of dark spots along the middle. Also known as pilchard, California sardine, California pilchard, sardina, sardine, they are fast growing and can grow to more than 12 inches long and can live up to 13 years, but usually not past five. [Source: NOAA]
Pacific sardines form large, dense schools near the ocean surface. They feed on plankton (tiny floating plants and animals). They are prey for many fish, marine mammals, and seabirds. Pacific sardines move seasonally along the coast. Spawning multiple times per season, they begin reproducing at age 1 or 2, depending on conditions. Females release eggs that are fertilized externally and hatch in about 3 days.
In North America, Pacific sardines are found along the west coast from Southeastern Alaska to Baja California, Mexico. Pacific sardines live in the water column in nearshore and offshore areas along the coast. They are sometimes found in estuaries. Older adults may move from spawning grounds in southern California and northern Baja California to feeding/spawning grounds off the Pacific Northwest and Canada. Younger adults appear to migrate to feeding grounds primarily in central and northern California..
Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se ; Encyclopedia of Life eol.org ; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems
Threatened Pacific Sardines and the Ban on Fishing Them
schooling Pacific sardines The Pacific sardines fishery in the U.S. was closed in 2015, and has not reopened. In 2014, more than 23,000 metric tons were harvested and were valued at $8.85 million. Round haul nets are used to catch Pacific sardines. Habitat and bycatch impacts are minimal because the gear is used at the surface around dense schools of fish, which usually contain only one species. [Source: NOAA]
Commercial fishing for Pacific sardines is prohibited because the population is estimated to be below a precautionary level set by managers and significantly below target population levels. A rebuilding plan is in place. The gear used to catch Pacific sardines is used at the surface and has little impact on habitat. Bycatch is low because gear used is selective.
According to the 2020 stock assessment, Pacific sardine is overfished, but is not subject to overfishing based on 2020 catch data. The population size varies naturally, which can lead to large fluctuations (boom-bust cycles) in abundance and catch. A precautionary measure is built into sardine management to stop directed fishing when the population falls below 150,000 metric tons. The latest population estimate is below that level, and managers have closed the fishery.
NOAA Fisheries and the Pacific Fishery Management Council manage the Pacific sardine fishery under the Coastal Pelagic Species Fishery Management Plan: It states: 1) Catch limits are in place to prevent overfishing; 2) Catch limit is allocated among three fishing seasons throughout the year; 3) Permits are needed to harvest Pacific sardines; 4) Gear restrictions are in place to reduce bycatch; 5) Catch is monitored through logbooks and observers.
The Pacific sardine fishery was at one time the largest fishery in North America. During the 1930s and ‘40s, peak sardine catches were as high as 700,000 metric tons, fueling the booming fishing and canning industry immortalized in John Steinbeck’s Cannery Row. But then the sardines vanished. natural population fluctuations. Harvest fell to an average of about 24,000 tons in the final years of the fishery, and a moratorium eventually shut down commercial fishing from 1967–1986. [Source: Fishbio, Monday June 11, 2018]
Tony Barboza wrote in the Los Angeles Times: The Pacific sardine is the ocean’s quintessential boom-bust fish. It is short-lived and prolific, and its numbers are wildly unpredictable, surging up and down in decades-long cycles in response to natural shifts in the ocean environment. When conditions are poor, sardine populations plunge. When seas are favorable, they flourish in massive schools. It was one of those seemingly inexhaustible swells that propelled California’s sardine fishery to a zenith in the 1940s. Aggressive pursuit of the species transformed Monterey into one of the world’s top fishing ports.[Source: Tony Barboza, Los Angeles Times, January 5, 2014]
West Coast Sardine Crash
And then it collapsed. By mid-century sardines had practically vanished, and in the 1960s California established a moratorium on sardine fishing that lasted 18 years. The population rebounded in the 1980s and fishing resumed, but never at the level of its heyday.
Since the 1940s scientists have debated how much of the collapse was caused by ocean conditions and how much by overfishing. Now, researchers are posing the same question. “It’s a terribly difficult scientific problem,” said Russ Vetter, director of the Fisheries Resources Division at NOAA’s Southwest Fisheries Science Center.
Separate sardine populations off Japan, Peru and Chile fluctuate in the same 50- to 70-year climate cycle but have been more heavily exploited, Vetter said. West Coast sardines are considered one of the most cautiously fished stocks in the world, a practice that could explain why their latest rebound lasted as long as it did. The West Coast’s last sardine decline began in 1999, but the population shot back up by the mid-2000s then went down again in the early 2010s.
.The reason for the drop is unclear. One factor is a naturally occurring climate cycle known as the Pacific Decadal Oscillation, which in recent years has brought cold, nutrient-rich water to the West Coast. While those conditions have brought a boom in some species, such as market squid, they have repelled sardines.
Impact of Sardine Crashes
Some ocean predators starve or at least have their lives seriously disrupted without sardines. Tony Barboza wrote in the Los Angeles Times: Scarcity of prey is the leading theory behind the 1,600 malnourished sea lion pups that washed up along beaches from Santa Barbara to San Diego in early 2013, said Sharon Melin, a wildlife biologist at the National Marine Fisheries Service. Melin’s research indicates that nursing sea lion mothers could not find fatty sardines, so they fed on less nutritious market squid, rockfish and hake and produced less milk for their young in 2012. The following year their pups showed up on the coast in overwhelming numbers, stranded and emaciated. “We are likely to see more local events like this if sardines disappear or redistribute along the coast and into deeper water,” said Selina Heppell, a fisheries ecologist at Oregon State University. [Source: Tony Barboza, Los Angeles Times, January 5, 2014]
Biologists also suspect the drop is hurting brown pelicans that breed on California’s northern Channel Islands. The seabirds, which scoop up sardines close to the ocean surface, have shown signs of starvation and have largely failed to breed or rear chicks there since 2010. Though pelicans have had more success recently in Mexico, where about 90 percent of the population breeds, environmental groups think the lack of food at the northern end of their range could threaten the species’ recovery. Normally, pelicans and sea lions would adapt by instead gobbling up anchovies. But aside from an unusual boom in Monterey Bay, anchovy numbers are depressed too.“That does not bode well for everything in the ocean that relies on sardines to get big and fat and healthy,” said Steve Marx, policy analyst for the Pew Charitable Trusts, a nonprofit that advocates for ecosystem-based management of fisheries.
Fishermen also attest to the scarcity. The West Coast sardine catch oscillates with the market and was valued at about $14.5 million in 2013, according to the National Marine Fisheries Service. But California fishermen pulled in just $1.5 million worth of sardines last year, preliminary data from state Department of Fish and Wildlife show. Just a few years ago, Hanson, the sardine captain, didn’t have to travel far from port to pull in nets bulging with sardines. Not anymore. If his crew catches sardines these days, they are larger, older fish that are mostly shipped overseas and ground up for pet or fish food. Largely absent are the small and valuable young fish that can be sold for bait or canned and eaten.
Great Sardine Run Off South Africa
Once a year during the Southern Hemisphere’s winter in the waters off east coast of South Africa billions of sardines gather in massive schools and migrate north with dolphins, shark, tuna, seals, seabirds and other predators in hot pursuit. The “sardine run” begins in deep, cold water off Cape Agulhas, Africa’s southernmost pont, and swim north past the beaches of Kwa-Zulu-Natal province and the port city of Durban. The schools are tracked by spotter planes, Some of them are seven kilometers long, 1.5 kilometers wide and 30 meters deep.
Upwelling caused by currents drives the “sardine run” but any aspects of it puzzle scientists. Why, for example, do the sardines first leave nutrient-rich feeding grounds for warmer waters that have far less nutrients in them. Evidence gathered using thermal imaging from satellites seems to suggest currents that carry cools water up the coast and trigger plankton growth are the driving force behind the run. In years when warm water invades the coast the run doesn’t occur.
Kennedy Warne wrote in National Geographic: Sardines are winter's gift to South Africa's east coast waters: an all-you-can-eat seafood buffet that attracts diners by the tens of thousands. Sharks, seals, seabirds, dolphins, and game fish converge on vast schools of Sardinops sagax, the South African pilchard, or sardine, which migrates northward along the coasts of the Eastern Cape and KwaZulu-Natal between May and August. On shore the fever can be almost as great as in the shoals. People flock to the coast, where beach seiners haul in bulging netfuls of sardines. Sometimes nets are superfluous. Forced inshore by predators, shoals simply wash up in the surf-glittering sardine waves that dump fish knee-deep on the sand. [Source:Kennedy Warne, National Geographic, August 2002]
Although there are three other major upwellings in the world — off the coasts of California, Peru, and northwest Africa — only in South Africa is the cold, productive west coast upwelling influenced by a warm, fast-flowing east coast current. The sardine run is an indirect result of that interplay. By rights sardines shouldn't be on the eastern coast at all. They are cold-water fish, and their stronghold is the southern and western coasts, where the Benguela holds sway. There they are harvested in their billions by purse seiners and turned into fish meal or cooked, sauced, tinned, and sold under a dozen different brands (one describes the product as "brainpower food"). Together with their close relatives the anchovies and herrings, sardines make up about a quarter of the world's fish catch.
For most of the year inshore water temperatures on the east coast are warmer than 68 degrees Fahrenheit (20 degrees Celsius) and outside the sardines' comfort zone. But in winter a combination of cooling land breezes and a mild upwelling of Agulhas Current waters onto the continental shelf creates a narrow, cool-water corridor that sardines can exploit. It is as if the eastern potentate had turned his back for a moment. The sardines, seizing their opportunity, move northward, find the corridor, and stream up the coast like lemmings. Once they reach Durban, those that haven't been caught, eaten, or beached spread out onto the continental shelf to feed and spawn. As the surface waters are warmed by the growing heat of the spring sun, the sardines descend to cooler depths, but eventually rising temperatures drive them back south to rejoin the parent population off the Eastern Cape.
Chasing Great Sardine Run off South Africa
Not many of South Africa's sardines choose the travel option — perhaps 30,000 tons (27,215 metric tons) of fish in all — but enough do for the KwaZulu-Natal sardine run to be considered one of the marine wonders of the world...The front-runners of the sardine migration: pilot shoals of perhaps half a million fish start to appear about the first week of June. The main shoals come some weeks later. These mother ships of the sardine fleet can cover several square miles and contain hundreds of millions of fish.
Kennedy Warne wrote in National Geographic: We based ourselves at Mkambati Nature Reserve, just south of the KwaZulu-Natal border with the Eastern Cape. Mkambati is one of the few places along this cliffbound stretch of coast where a boat can be launched During our weeks at Mkambati we dived on dozens of shoals, and every one was different. Some shimmered like blue carpets that suddenly turned silver as the fish caught the sun on their sides. Some were so solid and dense right down to the seafloor that swimming underneath them was like crawling under a mattress — and just as dark. Others were on the move, specks of light streaming ceaselessly toward us as mesmerizing as a computer screen saver. Sinking down into one shoal, I found myself in the hole of a sardine doughnut, being watched by innumerable unblinking yellow-rimmed eyes.
We found schools with just a few seals in attendance, not feeding so much as playing with the shoal — treating it as a living beach ball. Watching sardines part and re-form around a seal is like watching some super — organism reshaping itself with effortless mathematical precision. Occasionally our inflatable brought us upon the scene of a bait ball that had dissipated — or been consumed — nothing remaining but a few scales and a lingering smell of sardine oil.
Predators and Great Sardine Run off South Africa
Where warm and cold waters meet and Atlantic and Indian Oceans merge, huge schools of sardines form that attracts a menagerie of predators. Copper sharks force sardines into huge doughnuts and then move in for a bite. Common dolphins work together to drive the sardines towards the surface where they feast on the cornered fish. “David Doubilet wrote: “The dolphins shriek as they slash through the bait like people screaming on a roller coaster. I’ve never heard anything quite like it.” [Source: National Geographic, August 2002]
An estimated 18,000 dolphins and sharks and thousands of other fish consume the sardines. Many of them attack from below, while thousands of seabird such as gannets attack from above. Tourist can go out in boats and watch the phenomena and see 2,500 dolphins, covering the sea, swim past. The dolphins hunt by forcing the sardines into balls and attacking their edges (See Dolphins). How the slower sharks hunt is still unknown. In many cases it seems like they just hang around outside the fray and pick up stragglers.
Kennedy Warne wrote in National Geographic: In our search for shoals, it was the gannets we saw first in the distance, looking like swirling flecks of ash. If lucky, we would arrive to find the glorious chaos of a fully developed bait ball. These aggregations of ultimate frenzy are created when common dolphins ("common" both in name and number) work together to shear off a section of a shoal, corral it into a scrum the size of a tennis court, and force it to the surface. Only then do other predators appear, making the whole thing, as Addison says, "go ballistic." [Source: Kennedy Warne, National Geographic, August 2002]
The result is an eruption of fin and flesh. Dolphins squeal like sirens as they make strafing runs at the edges. Eight-foot (2.4-meter) copper sharks thresh their way through the shoal, biting and gulping. Cape fur seals, elastic underwater acrobats, corkscrew up through the middle then flip backward, snapping up fish on the way over. And all the while gannets rain from the sky, so fast and so many that it looks as if they are being sucked into the ocean by a vacuum cleaner.
Wings folded to their sides, they plummeted into the sea like feathered missiles, leaving green bubble trails in their wakes... The water boiled with fish. It was as if this patch of sea off the eastern coast of South Africa had been turned into a pot of bouillabaisse — and everyone was falling to the feast. Scores of circling dolphins harried the sardine shoal into an ever tightening mass. Panicked sardines threw themselves into the air and splashed back into the melee. A pale pink dorsal fin sliced through the midst. Then another. "Copper sharks!" said Mark Addison, our boat skipper. "Fantastic! Look — three, four, five of them." Tails lashing, they lunged and rolled in an orgy of feeding.
The presence of sardines must be a powerful drawcard for predators, for they come a long way to dine at the potluck. The nearest seal and gannet colonies are at Port Elizabeth, 300 miles (482.8 kilometers) south of Mkambati. Both species rest on the sea surface between feeding binges — gannets in large flocks, seals in rafts of a dozen or so, lying on their sides with a flipper raised in the air for cooling. On calm days we spotted dozens of seal rafts, each animal giving its one-flipper salute as we passed.
Dolphins and Sharks at Great Sardine Run off South Africa
Kennedy Warne wrote in National Geographic: Dolphins — bottlenose and common — are residents of this coast, but they are never here in such large numbers as they are during the sardine season. On one occasion Addison took Doubilet and me 10 miles (16.1 kilometers) offshore to dive with a thousand-strong herd of common dolphins traveling northward against the current. Addison dropped us in the water a mile (1.6 kilometers) ahead of the herd and retreated. We were in the heart of Agulhas country: over one shoulder the land a distant smudge, over the other a tanker crawling along the horizon toward the Cape, ahead a phalanx of dolphins advancing.
What is the sound of a thousand dolphins? It is like river rapids, or a sudden cloudburst. Close to the herd you can make out the individual pffffts of blowholes opening, stale air being expelled and fresh breaths sucked in. And, faintly through the puffs and splashes, the high-pitched squeaks and whistles of dolphin communication. Underwater, where those unearthly sounds are heard at full volume, it's like being serenaded by a chorus of dentist's drills.
The dolphins came on in a rush, wavefuls of them leaping out of the face of the ocean swells as if jet-propelled, the sunlight gleaming off their cornmeal-colored flanks. Streamlined and athletic, Olympians of their kind, they had a focused intensity about them. "Places to be, things to do," they seemed to be saying as they sped past.
Sharks, those legendary "swimming noses," were never far from the sardine supply. They had a knack for materializing out of seemingly empty ocean. You would think you were alone — and then there would be a shark only a few feet away. The main species associated with the sardine run is the copper shark (also known as the bronze whaler), but spotted ragged-tooth sharks also take the occasional sardine meal. Like other migrants along this coast, ragged tooths — known elsewhere in the world as gray nurse or sand tiger sharks — move north during sardine season from the cool southern waters to the tropics to breed.
Image Sources: Wikimedia Commons, NOAA
Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.
Last Updated April 2023