Blue mackerel

Scientific name: Scomber australasicus

Family: Scombridae

Other names: Pacific mackerel, common mackerel, English mackerel, school mackerel, spotted chub mackerel, spotted mackerel, chub mackerel, Japanese mackerel, southern mackerel, slimy mackerel, slimies

Description: Blue mackerel have a fusiform (‘spindle-like’) body covered in small scales. They have bluish to greenish backs and pale spotted bellies, with dark bars on the upper sides. Both the second dorsal fin and anal fin are followed by five to six finlets. The eyes have adipose (fatty tissue) eyelids that leave a vertical slit over the pupils.

Size (length and weight): Up to 65 cm in length and 1.5 kg. Commonly found at 20‑35 cm in length and 0.2‑0.7 kg.

Life span: Up to 7 years, but more commonly 1‑3 years.

Habitat: Blue mackerel are a schooling pelagic species that occurs in tropical and temperate waters of the Pacific Ocean. They can be found to depths of 200 metres over the continental shelf, although juveniles inhabit inshore waters and shallower waters. Blue mackerel tend to school by size, as well as with other fish such as jack mackerels. Feeding is thought to occur during the day.

Prey: Small fish, squid and plankton.

Predators: Seabirds and marine mammals such as seals and dolphins, and larger fish such as tuna and billfish.

Reproduction: Blue mackerel reach reproductive maturity at about 3 years of age. Spawning occurs in spring and summer in outer continental shelf waters off northern New South Wales and southern Queensland. Blue mackerel are serial spawners, with spawning events occurring over several months. Females produce about 70 000 eggs per spawning event depending on their body size

The Commonwealth catch of blue mackerel around the south of Australia is managed by quota. Which means the catch of this fish by commercial fishers is restricted by weight. AFMA also restricts the type of fishing gear that can be used to fish blue mackerel to prevent other non-target species being caught incidentally.

Commercial fishermen are required to fill in records of their catches, during each fishing trip and when they land their catch in a port. This helps us keep records of how much is being caught.

AFMA decide on the amount that can be caught each year from expert advice and recommendations from fisheries managers, industry members, scientist and researchers.v

Blue mackerel, are usually found in inshore waters and larger adults form schools in depths of 40-200 metres across the continental shelf.

In Australia, blue mackerel are found mainly in southern, temperate and subtropical waters between southern Queensland and Western Australia. Blue mackerel are also found throughout the Pacific Ocean, Northern Indian Ocean and Red Sea.

Fishing for Blue mackerel in the Small Pelagic Fishery has historically been focused off south east NSW, eastern Tasmania and South Australia.

Assessments indicate that fishing for blue mackerel is highly selective and has low rates of bycatch. However there are measures in place to minimise impacts on threatened endangered and protected species including:

• compulsory seal excluder devices for midwater trawl nets
• vessel management plans, outlining measures specific to the individual boats to minimise interactions with seabirds and threatened, endangered and protected species, such as seals and dolphins.

Gear

• Demersel (bottom) trawl
• Midwater trawl
• Purse seine