Taxonomy

Rarity

Abundance rates how many are in suitable habitat. Find difficulty rates how hard it is to locate one on a daylight snorkel or freedive through 50 ft. A higher find score means a harder search. The rarity category also reflects the kind of encounter; it is not an average of the 2 scores.

Seasonality

Location

Pacific sardine are a coastal open-water fish. They form large schools between the surface and about 660 feet, in water between roughly 48 and 70 degrees Fahrenheit. Adults hold between 61 and 73 degrees in summer and between 50 and 64 degrees in winter. Along California the schools migrate north in early summer and back south in autumn, and there is a detail in that pattern worth knowing: the older a sardine gets, the farther it travels. Each year of life extends the migration.

Diet changes as the fish grows. Young sardine eat zooplankton, the drifting animals of the open sea, particularly the tiny shrimp-like crustaceans called copepods. Adults shift toward phytoplankton, the drifting plants. A fish that eats plants is unusual among ocean fishes and is the reason sardine sit so low in the food web and so high in numbers. They are prey for many fish, marine mammals and seabirds, and common thresher sharks hunt them directly.

The identification feature is on the gill cover. A sardine has a set of clean bony ridges radiating downward across the lower part of the gill cover, and no other herring-family fish on this coast has them. The rest of the fish is a blue-green back, white flanks, and 1 to 3 rows of dark spots along the side.

Deep Dive

The story of the Pacific sardine is the story of the largest fishery the west coast ever had, and of what happened to it twice.

Through the 1930s and 1940s the fishery pulled as much as 700,000 metric tons a year out of the California Current. That catch built Cannery Row in Monterey, and John Steinbeck wrote the street into a novel while the boats were still running. Then it ended. Landings fell through the late 1940s and 1950s to roughly 24,000 tons a year, and in 1967 California shut commercial sardine fishing altogether. The closure lasted until 1986. The cause was not a single villain. Fisheries scientists attribute the collapse to overfishing acting on top of a natural population swing, and the swing part matters, because Pacific sardine populations rise and fall on their own over decades regardless of what boats do.

The stock rebuilt through the 1990s and supported a fishery worth $10 to $20 million a year in the 2000s. It peaked in 2006. Then it fell again, faster than management responded, and in 2012 a published assessment warned that a second collapse was under way. The fishery closed in 2015 and has stayed closed for 11 years.

Underneath the fishery history is an animal built for exactly this kind of swing. Sardine mature at 1 to 2 years old and most spawn first in their second year. They release floating eggs into open water and the larvae drift. Australian work on the same species measured batch sizes from about 10,000 eggs in a 5 inch female to about 45,000 in a 7 inch female, which is a useful order of magnitude even though the measurement was not made in California. A fish that reproduces that fast can rebuild a population in a decade, and a fish whose whole life strategy depends on numbers can also lose one just as fast when ocean conditions turn.

The longevity figures deserve a note because they disagree. FishBase records a maximum reported age of 25 years for the species worldwide. NOAA says Pacific sardine typically live up to 13 years and most do not exceed 5. Both numbers are in print. The practical one for a California fish is NOAA's: most sardine in this ocean are dead before their sixth birthday, eaten by something bigger.

The name carries a small piece of history. The genus is built from the Latin word for sardine, which traces back to the island of Sardinia, plus the Greek word for appearance. The species name is Latin for quick-perceiving or alert, which is a reasonable thing to call a fish whose entire defense is noticing a predator at the same instant as 10,000 of its neighbors.

Where to Find Them

Researched habitat and range candidates

These locations have suitable habitat within the species range. An assignment is a possible encounter, not a confirmed sighting at every beach. Season, depth, and local conditions still matter. Historical habitat without present-day evidence is excluded.