American Oceans

Chub Mackerel

The Chub Mackerel, or scomber japonicus, is a species of fish in the tuna and mackerel family. Martinus Houttuyn is attributed to giving the Chub Mackerel its scientific name.

Chub Mackerel Scomber japonicus found in Indo-Pacific

The Chub Mackerel closely resembles the Atlantic Chub Mackerel, however, this species is found in the Indo-Pacific.

Other common names for the Chub Mackerel include the Pacific Mackerel, Pacific Chub Mackerel, and Striped Mackerel.

Fossils of this species have been found in the Pliocene of Italy that are as old as 2.2 million years. The Chub Mackerel is a popular dish in Sicilian and Korean cuisines.

Characteristics & Appearance

While the Chub Mackerel and Atlantic Chub Mackerel are similar species, they can be distinguished from each other by their appearances.

Weight & Length

The Chub Mackerel can grow between 8 and 14 inches long (20 and 36 centimeters) and weigh between 2 to 4 pounds (0.9 to 1.8 kilograms).

They are smaller than many other ocean fish species. Due to their small size, it can be hard to distinguish the species until caught.

Physical Characteristics & Color

Chub Mackerel are primarily a silver color and have bright green scales with vertical stripes down their bodies. These stripes start from the top of the fish and run almost halfway down their sides.

They have large eyes positioned on either side of their head and a pronounced lower jaw. Their scales are small and become more prominent around their pectoral fins. They use their reflective scales as a defense mechanism against predators.

Chub Mackerel have two main fins on either side of their body and two dorsal fins on the top and bottom.

The dorsal fin on its back has 9 to 10 spines. Their tail is deeply forked, allowing them to cut through the water quickly.

The Chub Mackerel’s body is designed to help it move through the water quickly. It has a well-developed swim bladder attached to its esophagus, allowing it to control its buoyancy in any water depth.

Lifespan & Reproduction

Chub Mackerel can live up to 18 years in the wild. On average, they live for between 13 to 15 years. They grow and mature quickly and can reproduce by age 4. Some Chub Mackerel grow quicker and can reproduce as early as age 1.

These fish migrate constantly during their lifecycle. In summer weather they migrate north, and in winter they migrate south.

They will also travel inshore and offshore – they’re more common inshore from July to November and more common offshore from March to May.

These mackerel spawn from late April to September near California, year-round off central Baja California with a peak from June to October, and late fall to early spring off Cabo San Lucas.

One Chub Mackerel can produce 70,000 eggs at once. These eggs typically hatch within 4 to 5 days.

Chub Mackerel start as larvae when newly hatched, becoming juveniles after a few months, and then fully grown adults.


Chub Mackerel live in both temperate and tropical seas. On average they are found in waters within temperatures ranging 50 to 70 degrees F. They tend to stay within 20 miles (37 kilometers) of coastal waters.

Generally, the Pacific Chub Mackerel lives in Indo-Pacific waters. They can be found from southeastern Alaska to Mexico, but are most commonly found south of Point Conception, California.

This differs from the Atlantic Chub Mackerel, which is found in the Mediterranean Sea, the Black Sea, and the Atlantic Ocean.

Where Do Chub Mackerel Live?

Adults will stay in deep waters of 1,000 feet (300 meters) during the day. At night, they will come up to open water when threats from the sky are minimal.

Chub Mackerel migrate in large schools for long distances across the ocean. They may school with other types of mackerel and pelagic (oceanic) species as well.

Chub Mackerel spend their entire day swimming in search of food. They have good social behavior, which is why they travel and hunt in groups. Larger fish school together, and smaller fish form separate shoals.

Food & Diet

Chub Mackerel are in constant competition for food with other fish in their ecosystem. They are carnivores in the middle of the food chain, and they love to eat. This species will travel to open waters at night to feed rather than hunt during the day.

What Do Chub Mackerel Eat?

When Chub Mackerel first hatch, they feed on copepods and rotifers (microscopic organisms). As they grow, they will start eating zooplankton (plankton consisting of small animals and the immature stages of larger animals).

Once they mature fully, they feast on small shrimps, amphipods, salps, larvacea, and krill. It has even been known to feed on its own young and that of other fish (anchovies, sardines, and small herring).

Chub Mackerel, like other mackerel species, hunt via ram feeding. Not only do they migrate in schools, but they hunt in these shoals as well.

Ram feeding is when all of the fish in the school swim with their mouths open, engulfing prey as the school swims by.

Some Chub Mackerel may also break away from the group to feed on their own. Regardless of water temperatures, a Chub Mackerel’s metabolism does not change.

It will continue to eat as much food as it can daily for its entire lifespan. In colder water, the Chub Mackerel may be idler throughout the day and not hunt as often.

Threats & Predators

Chub Mackerel are located in the middle of the oceanic food chain and are also a popular commercialized fish across the globe.

Human Threats

Chub Mackerel are a common species for fishermen to capture, but at this time they are not in danger of overfishing.

They naturally experience “boom and bust” cycles of abundance, which is normal for small ocean fish.

Pollution poses a threat to all ocean organisms. If a Chub Mackerel tries to eat trash like plastic, it will certainly die.

This pollution also affects the Chub Mackerel’s living space, creating a dangerous environment that can harm them.

Climate Change & Global Warming

As global warming continues to affect our planet, average temperatures in the oceans are slowly rising. This can change migration patterns for Chub Mackerel as well as breeding locations.

It has been noted that since the 2000s, the spawning ground for Chub Mackerel has moved north as those waters warmed to their liking.


Larger fish like sharks and tuna prey on Chub Mackerel, as well as marine mammals and seabirds.

Chub Mackerel travel in schools to confuse predators by moving together to simulate waves, making it hard for predators to distinguish where they are.

They also hide from seabirds by moving closer to the surfacing, allowing their scales to reflect the sun’s light.

Other Threats

Historically, the Chub Mackerel population remains at a relatively low abundance level. This is primarily due to oceanographic concerns like pollution, overexploitation of fishing resources, unsustainable aquaculture, and oil drilling.

If for any reason their population drastically decreases, they would be susceptible to overfishing as well.

Conservation Status

The Chub Mackerel’s conservation status is currently “Least Concern”. Their population is above target population levels, which means they are not at risk of overfishing or endangerment.

Although the population has been decreasing historically, the Chub Mackerel is one of the oldest known species of fish, so this is not concerning.

Fun Facts About Chub Mackerel

  • Chub Mackerel communicate through sounds, motions, smell, color, and bioluminescence to alert their school of predators
  • Chub Mackerel are sustained swimmers
  • Chub Mackerel swim an average of 2.05 mph with a burst speed of 5.13 mph
  • Atlantic Chub Mackerel can swim faster than Pacific Chub Mackerel at 2.19 mph with a bust speed of 12/3 mph
  • Chub Mackerel are rich in omega-3 and unsaturated fatty acids
  • Chub Mackerel are often used as pet food, but should not be kept as pets because they live in large schools and constantly move in ocean waters
  • Chub Mackerel are primarily differentiated from other mackerel by their number of finlets

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