Pacific Chub Mackerel
Scomber japonicus

Physical Description

• A medium-sized, slender, football-shaped fish with a pointed head and a large mouth.
• Dark blue coloration on back and head, silver coloration on the belly, with mottling and small dusky blotches on the top.
• Have a pointed dorsal (back) fin resembling that of related species.
• They can be up to 25 inches long and up to 6 pounds.

Range

• Southeastern Alaska to Mexico.
• Most common south of Point Conception, California.

Habitat

• Lives in the open ocean within twenty miles of shore.
• Juveniles live off of sandy beaches, in open bays, and around kelp forests.
• Adults live near shallow banks, from depths of 0 to 1000 feet.

Reproduction

• They reproduce by age 4, though some as early as 1.
• Spawning is at different times of year, based on location. It is year-round off of central Baja California, from late April-September off of California, and from late fall-early spring off Cabo San Lucas.
• They spawn several times a year, releasing ~70,000 eggs each time.
• The eggs hatch in 4-5 days.

Diet

• As juveniles, they feed mainly on copepods and rotifers and larval anchovies and sardines.
• Sometimes even eat smaller larvae of their own kind.
• As adults, they feed on mysids and euphausiids (krill).

Predators

• Large fish, sharks, tunas, marine mammals, seabirds.
• Humans.

Interesting Facts

• Fossils of this fish have been found in the Pliocene of Italy (meaning they were around 2.2 to 3 million years ago)!
• Chub mackerel larvae can consume up to 87% of their dry body weight a day!
• They often school in large schools for defense, including with sardines and jack mackerel.

Sources: Diet of Larvae(n.d.). ulpgc.es. Retrieved April 21, 2013, from acceda.ulpgc.es/bitstream/10553/327/1/551.pdf; Paleobiology Database; NOAA Fisheries; NOAA Fishwatch

Photo: Kevin Lee