Broadbill swordfish

Scientific name: Xiphias gladius

Family: Xiphiidae

Other names: Swordfish, broadbill

Description: Broadbill swordfish have long, cylindrical bodies that fade from blackish-brown on the back and sides to light brown on the underside. The membrane of the first dorsal fin is usually black. Adults lack scales, teeth and pelvic fins. Broadbill swordfish have a long bill that they use to stun or kill prey.

Size (length and weight): Up to 4.5 metres in length and 500 kg. Commonly found at 1.5‑3 metres in length and 70‑150 kg. Females grow faster than males.

Life span: Up to 15 years. Females live longer than males.

Habitat: Broadbill swordfish are highly migratory and are found throughout the Atlantic, Indian and Pacific Oceans. They are primarily a warm-water species that moves into cooler, temperate waters for feeding during the Australian summer months and returns to warmer tropical waters for spawning and over-wintering. They are usually found to depths of about 550 metres. Adults are generally solitary.

Prey: Other fish (e.g. silver hake, redfish, herring and lanternfishes), crustaceans, squid and cuttlefish.

Predators: Adult broadbill swordfish are sometimes preyed on by orcas and large sharks. Juveniles are preyed on by a wide range of predators including tunas, marlin, sailfish and sharks.

Reproduction: Broadbill swordfish reach reproductive maturity at 5-6 years old (although research in 2004 suggested that maturity may not occur until 10 years of age). Spawning appears to occur throughout the year in tropical waters, but is restricted to spring and summer at higher latitudes. Females are serial spawners and release eggs up to 90 times at intervals of about 2.5 days during the spawning season. Females produce 1.2‑2.5 million eggs per spawning event depending on their body size.

Other notes: The colour of the flesh can range from white to orange to pink depending on the diet of the fish.

AFMA manages catches of broadbill swordfish with a total allowable catch limit. This restricts the weight of fish that can be caught by each commercial fisher. To further manage the Australian catches of broadbill swordfish, commercial fishers are required to fill in records of their catches, during each fishing trip and when they land their catch in a port. AFMA also restricts the type of gear that can be used to fish for broadbill swordfish.

As broadbill swordfish is caught by many other countries in the western and central Pacific Ocean and the Indian Ocean, this species is also managed internationally. The Western and Central Pacific Fisheries Commission and the Indian Ocean Tuna Commission are the international bodies responsible for managing the world’s tropical tuna and billfish catch in the Western Pacific Ocean and the Indian Ocean. Australia is a participating member of both Commissions and AFMA has to follow the decisions made by both these Commissions when managing the Australian catch of broadbill swordfish.

Broadbill swordfish is an oceanic species and is caught worldwide throughout tropical, temperate and occasionally cold waters. They are commonly found in eastern Australian waters, but they are also found in the waters of other countries within the Pacific and Indian Oceans.

In Australia, broadbill swordfish are caught anywhere along both the east and west coasts and it is a targeted species by fishers in both the Eastern Tuna and Billfish Fishery and the Western Tuna and Billfish Fishery.

Fishers use pelagic longline gear to catch Broadbill swordfish. These longlines hang in the water column and do not touch the seafloor. There are low levels of bycatch when fishing for Broadbill swordfish, but some sharks, seabirds and other species may be caught when using longline fishing gear.

Ecological risk assessments are done for the Eastern Tuna and Billfish Fishery and all other fisheries to find out if the fishing of broadbill swordfish is harming other species. The most recent assessment was done in 2009 and the risk to other species was assessed as low.

Gear

• Pelagic longline
• Minor line