Northern anchovy (Engraulis mordax): the filter-feeding forage fish behind seabirds, salmon and sea lions all along the Pacific kelp coast.
If the Pacific kelp coast ran a food drive, the northern anchovy (Engraulis mordax) would be the tinned goods: small, ubiquitous, calorie-dense, and essential beyond its modest profile. At twelve to fifteen centimetres long, an anchovy is about the least impressive fish you will ever see wall-to-wall — and the biomass of a big anchovy year can dwarf that of its better-known cousin, the Pacific sardine.
Almost everything with fins, wings or flippers between Baja California and British Columbia eats anchovies when it can. Salmon grow fat on them. Brown pelicans time their nesting to them. Humpback whales will abandon krill to lunge through them. This is a profile of the small fish at the bottom of everything — including the reason seabirds starve in an apparently full ocean.
The northern anchovy is the eastern Pacific member of the anchovy family (Engraulidae), a group of small, silvery schoolers instantly recognisable by the undershot jaw: the snout projects a stubby nose over a mouth that opens huge relative to the fish. They are built like art sent through a fax machine — a silver smear of a sardine, a head mostly mouth.
The species ranges from the Queen Charlotte Sound in British Columbia to Baja California and the Gulf of California, but it is not one continuous horde. Biologists recognise several subpopulations or stocks — a small northern group off the Pacific Northwest, a vast central subpopulation centred off Southern California and northern Baja, and a southern group further down the Baja peninsula. The central subpopulation is the giant: when conditions go its way, it can account for millions of tonnes and is arguably, in a good year, one of the largest fish biomasses in any temperate sea. (The Peruvian anchoveta, a close relative Engraulis ringens, still holds the volume records — see our guide to Paracas and the Peruvian upwelling.)
Like sardines, anchovies feed at the bottom of the food web — but they lean slightly more on zooplankton (copepods, krill, fish larvae) while retaining the unusual ability among fishes to strain tiny phytoplankton directly. They spawn for the first time at about a year old, release pelagic eggs in coastal waters almost year-round with a winter–spring peak, and live fast: three or four years is a good anchovy age, seven is geriatric.
That short fuse is a strategy. An anchovy cannot wait out a bad decade; it must multiply through the good ones. A year-class of anchovies born into a cold, plankton-rich spring — when coastal upwelling has turned the whole shelf green — can swell the population several-fold. The crash, when the warm years starve the plankton, is equally fast. Anchovies live on fast-forward.
One of the most satisfying patterns in oceanography is that sardines and anchovies almost never peak together. Warm, slow years favour sardines; cool, sharply upwelled years favour anchovies. The proxy records in anoxic seafloor sediment — annual layers of fish scales laid down off Southern California — show the two species oscillating against each other like pendulums out of phase for nearly two millennia.
The reasons are debated, but the pattern is robust: anchovies seem to thrive where cool water and strong upwelling pack the surface ocean with large, fatty plankton in a small, coastal area — what oceanographers sometimes call a "compressed habitat" — while sardines orbit the warmer, more stratified offshore ocean. Where the two overlap, they are kept at one another's throats by the physics of the coast. You can read a surprising amount of climate history just by counting which species' scales fell in which year.
For predators that live on both — common murres, sea lions, pelicans — the see-saw is insurance: usually at least one of the two is in season. The dangerous years are the rare ones when both decline together, which is precisely what happened across parts of the California Current in the mid-2010s, when warm-anomaly years broke up the cold coastal plankton the anchovies needed while sardines were already down. California sea lion pups stranded by the thousands along Southern California beaches; seabird breeding failed on the Farallones and the Channel Islands within a season of one another.
On the actual kelp bed, anchovies are the weather — the moving sky of fish above the reef. Divers on Monterey Bay or the Southern California Bight know the look: a low ceiling of silver just off the kelp canopy, dimming and brightening as the school passes, while kelp bass and yellowtail work the underside like sheepdogs. At the reef edge, kelp forest predators hunt anchovies the way coyotes hunt a field edge — using the forest's structure as a wall against which to press the school.
The anchovy schools themselves are a piece of infrastructure for seabirds. Common murres, auklets, terns and pelicans are pursuit- and plunge-divers that cannot chase fish across open ocean; they need dense, surface-schooling prey. Anchovies obligingly hold in tight, predictable patches close to shore, so almost every murre colony on the California coast is effectively an anchovy colony in disguise. When the schools fail, the birds have nothing to absent-mindedly walk down to.
Juvenile anchovies use bays, sloughs and the quiet shallows beneath kelp fringes as nursery grounds. Those fringe habitats are increasingly where the elbow room is disappearing — filled, dredged or armoured against the sea — and they are exactly the sites coastal councils are being asked to think harder about (see our work with coastal councils).
For such an enormous biomass, the northern anchovy supports an oddly small directed fishery on the American west coast — chiefly live bait for recreational fisheries, plus dead bait and a little human food. The reasons are history and economics more than biology: the reduction fishery of the sardine era passed the anchovy by, international fleets did not industrialise the California stock the way they did the Peruvian anchoveta, and American fishmeal demand was met by imports.
That light direct pressure does not make the stock safe. Forage fish are mostly threatened by what we are not doing to them: warming seas, shifting upwelling timing, and the vast, unmeasured take by all the predators the management plans do not count. A harvest rule that treats an anchovy stock like a cod stock mis-serves the whole coast; the modern trend — as with the sardine — is to model the predators' share in explicitly and set quotas for whatever is left once the ecosystem has eaten first.
Not currently. Unlike the sardine, the northern anchovy's central subpopulation rarely supports a large directed US fishery and is watched as much for climate signals as for catch limits. Managing authorities still track biomass carefully because so many protected predators depend on it; the greater risk is a run of poor ocean years, not nets.
Different families and different filters of the same job. Anchovies (Engraulidae) are smaller, mouth-forward filter feeders, shorter-lived and more coastal; sardines are herrings (Clupeidae), larger-bodied, longer-lived and broader-ranging offshore. They eat much the same plankton and take turns dominating the California Current on decade-long timescales.
No. The classic tinned Mediterranean anchovy is Engraulis encrasicolus, a close relative. Northern anchovies are eaten locally and are excellent prepared the same ways — salt-cured, pickled or grilled — but little of the regional catch goes to cans, and most is used as bait.
A sequence of cool, strongly upwelled years followed by rich coastal productivity concentrated anchovies in a narrow band close to shore; the schools in 2014 and 2015 were big enough to draw humpback whales into Monterey Bay and huge rafts of shearwaters to the beaches. That's the anchovy's nature: extreme responses to short windows of good ocean.
Often, yes. Scan for wheeling bird aggregations, sudden "hot water" patches where pelicans plunge, or a dim band of silver just off the kelp canopy on a calm day. A pier or headwork above a bay in summer can put you right over the top of a school — watch it ripple, and watch everything else arrive.
Pacific sardine: the ecology of Sardinops sagax, its great twentieth-century collapse and recovery, and why this small fish feeds the whole kelp coast.
Dr. Mara Ellison ·
Pacific herring (Clupea pallasii): the life cycle behind the spawn that whitens beaches, the predators it feeds, and why kelp beds still matter.
Tom Okafor ·
Meet the common murre, the foot-propelled pursuit diver of kelp-coast upwellings — a flying auk that hunts 100 metres down and raises chicks on bare cliffs.
Dr. Mara Ellison ·