Family XIPHIIDAE


Common name: Swordfish

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Summary:

Swordfish can maintain body temperatures higher than the surrounding water while hunting for prey. Even more remarkably, they have a 'brain heater' and can selectively heat their eyes and brains up to 15 °C above the water temperature. This greatly improves their ability to see and catch prey in deep, cold water, making them very successful hunters.

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Cite this page as:
Swordfish, XIPHIIDAE in Fishes of Australia, accessed 26 Apr 2017, http://fishesofaustralia.net.au/Home/family/271

More Info


Family Taxonomy

A monotypic family comprising a single species, the Swordfish, Xiphias gladius.

Family Distribution

Worldwide in oceanic regions, throughout tropical, temperate and, occasionally, cold waters, between approximately 60°N to 45°S. Pelagic, chiefly found in surface waters, to a depth of 650 m. This highly migratory species overwinters and breeds in warmer waters, migrating to cooler waters during summer months. Swordfish often live around seamounts and boundary current zones, where productivity is high. 

Family Description

Characterised by a long flattened, sword-like bill, a single cadual keel and no pelvic fins or scales in adults. Two widely-separated dorsal fins are present, the first short-based, the second small and set far back on the body. Two anal fins are present, the first much larger than the second. The lateral line is absent in larger individuals.

Family Size

Females reach a length of 4.55 m, and a weight of 650 kg, whereas the smaller males reach a maximum size of about 3 m.

Family Colour

Body brownish-black above, becoming lighter below. The fins are brown or dark brown.

Family Feeding

This voracious oceanic predator feeds mostly on a variety of pelagic fishes, squids and cuttlefishes captured over a wide depth range. Like the related billfishes, the Swordfish thrashes its bill to injure or kill prey, before consuming it. Studies have shown that most larger prey items have been 'slashed', whereas smaller prey is swallowed whole. Juveniles feed on squid, fishes and pelagic crustaceans.

Family Reproduction

Sexes are separate, and Swordfish mature at about 5-6 years of age. Fertilization is external, and Swordfish are batch spawners in tropical waters during spring and summer months; eggs and larvae are pelagic.

Family Commercial

Of high commercial importance in tropical and temperate waters worldwide and usually taken on commerical longlines. Also a very popular and highly prized sport fish. Major fishing areas for this species are off the eastern United States, western-central America, and off eastern Australia and New Zealand.

Swordfish meat is primarily sold as fillets or steaks, and is valued in Asia as an ingredient in sashimi or sushi. The flesh may contain high mercury levels. 

Family Conservation

International: The North-Pacific Stock is listed as Data Deficient on the 2010 IUCN Red List of Threatened Species. IUCN Red List - Swordfish

Family Remarks

Similar families include the Istiophoridae (Marlins and Spearfishes) which can be distinguished by the presence of pelvics fins and two caudal keels.

Xiphiidae is from the Greek xiphos meaning sword, in reference to the long sword-like bill.