Billfish
| Billfish | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
 Striped marlin, Tetrapturus audax
| ||||||||||
| Scientific classification | ||||||||||
| ||||||||||
|
Istiophorus (sailfishes) |
Billfish is the common name for any of the large, predatory marine fish comprising the families Istiophoridae and Xiphiidae of the Perciformes order, characterized by large size, elongate premxillary bill, two anal fins, and pectoral fins low on the body. The Xiphiidae family has one extant member, Xiphias gladius, known as the swordfish. The Istiophoriidae has about 11 species placed in three genera: the sailfishes comprising genus Istiophorus, the spearfishes of genus Tetrapturus, and the marlins of genus Makaira.
They are important apex predators feeding on a wide variety of smaller fish and cephalopods. While billfish are most common in tropical and subtropical waters, swordfish in particular are sometimes found in temperate waters as well.
Overview and description
Suborder and family placement and characteristics
The term billfish generally refers to any of the members of the families Istiophoridae and Xiphiidae (Collette et al. 2006). However, at times the term billfish is reserved for members of the family Istiophoridae (Nelson 2006; Hebrank et al. 1990). In this article, the more inclusive terminology will be used.
Nelson (2006) places the two families of billfishes, Istiophoridae and Xiphiidae, as part of the suborder Scombroidei within the family Perciformes. Perciformes ("perch-like") is the most diverse order of ray-finned fish and includes such familiar members as perches, basses, sunfishes, bluefishes, cichlids, mackerels, and tunas. The Scombroidei suborder includes fish that have an upper jaw that is not protrusible, with the premaxilla fixed (an adaptation to feeding on larger prey). The suborder includes species that likely are the fastest swimming fish in the world, including bluefin tuna, swordfish, and sailfish (Nelson 2006). Other members of the suborder include barracudas, mackerels, and snake mackerels.
However, Collette et al. (2006) maintain that billfish are morphologically and genetically distinct from scombroids to be placed together in a separate suborder, Xiphioidei. Nelson (2006) also notes that the two families, Xiphiidae and Istiophoridae, share enough characters that they should be considered sister groups. He notes the following more visible shared characteristics: elongate premaxillary bill (rostrum) in adults; dorsal fin origin over back of head; first dorsal fin lacking true spines and with 37-55 rays; two anal fins; mouth inferior; pectorals low on body; reduced pelvic fins with one spine and two rays or absent; gill membranes free from the istmus; and 24 or 26 vertebrate.
The various billfishes (sailfishes, swordfish, marlins, and spearfishes) are generally separated into two families, the Xiphidae and Istiophoridae, with the swordfish (Xiphias gladius) the only extant member of Xiphiidae, and the other billfishes placed within three genera within Istiophoridae (ITIS 2004; Agbayani 2008). The three genera placed in Istiophoridae are Istiophorus (sailfishes), Tetrapturus (spearfishes), and Makaira (marlins) (Nelson 2006; ITIS 2004).
In some classifications, swordfish are placed together with the sailfishes, marlins, and spearfishes in the family Xiphiidae (Nelson 1994). That is, all the fish known as billfishes are placed together in this one family, with four extant genera with 12 species in the family. Nelson (1994) follows this procedure because "there is abundant evidence that the formerly recognized Xiphiidae and Istiophoridae are sister groups" and that as terminal groups in Scombroidei "they should be placed in the same family." As a comprehensive billfish family, Nelson (1994) characterizes Xiphiidae by adults having an elongate, premaxillary bill (or rostum), as well as an inferior mouth, the dorsal fin beginning over the back of the head, and the dorsal fin lacking any true spines and from 37 to 55 rays (Nelson 1994, p. 428). The billfishes also lack finlets behind the dorsal and anal fins, have two anal rays, the pectoral fins are inserted low on the body, the pelvic fins are reduced (one spine and two rays or absent), and the gill membranes are free from the isthmus (Nelson 1994, p. 428).
A notable characteristic of the billfishes is the remarkable ability to practice a form of endothermy, a type of warm-bloodedness where an elevated body temperature is maintained through internal means. Billfish exhibit a type of endothermy known as cranial endothermy whereby only the brain and eyes are warmed (Nelson 1994; Block et al. 1993). They remain "cold-blooded" (specifically poikilothermic) in that they do not maintain constant internal temperatures and the temperature often mirrors the ambient temperature. But by being able to raise the temperature of their brains and eyes, they can have faster eye movements when hunting, which is valued when diving deep into the ocean where the water is very cold.
applied to a number of different large, predatory fish characterised by their large size (swordfish can be over 4 metres long) and their long, sword-like bill. Billfish include the sailfish and marlin, which make up the family Istiophoridae, and the swordfish, sole member of the family Xiphiidae.
Taxonomy
Family Istiophoridae
- Genus Istiophorus
- Istiophorus albicans - Atlantic Sailfish
- Istiophorus platypterus - Indo-Pacific Sailfish
- Genus Makaira
- Makaira indica - Black Marlin
- Makaira mazara - Indo-Pacific Blue Marlin
- Makaira nigricans - Atlantic Blue Marlin
- Genus Tetrapturus
- Tetrapturus albidus - Atlantic White Marlin
- Tetrapturus angustirostris - Shortbill Spearfish
- Tetrapturus audax - Striped Marlin
- Tetrapturus belone - Mediterranean Spearfish
- Tetrapturus georgii - Roundscale Spearfish
- Tetrapturus pfluegeri - Longbill Spearfish
Exploitation and conservation
Billfish are exploited both as food and as game fish. Marlin and sailfish are eaten in many parts of the world, and important sport fisheries target these species, for example off the Atlantic coast of Florida. Because of worries about declining populations, sport fishermen and conservationists now work together to gather information on billfish stocks and implement programs such as catch and release, whereby fish are returned to the sea after they have been caught.
Swordfish are large and have meat that is firm and tasty, and are subject to intense fisheries pressure, and in many places where they were formerly abundant they are now comparatively rare.
marlin are part of the swordfish family.
ReferencesISBN links support NWE through referral fees
- Agbayani, E. 2008. Istiophorus albicans, Atlantic sailfish FishBase. Retrieved May 22, 2008.
- Integrated Taxonomic Information System (ITIS). 2004. Istiophoridae ITIS Taxonomic Serial No.: 172486. Retrieved June 1, 2008.
http://jeb.biologists.org/cgi/reprint/148/1/449.pdf Hebrank et al. 1990
ISTIOPHORID BILLFISHES
http://web.vims.edu/fish/faculty/pdfs/jeg_Collette_et_al_%202006.pdf?svr=www Collette et al. 2006
External links
- Family Istiophoridae at Fishbase.org
- Family Xiphiidae at Fishbase.org
- The Billfish Foundation
- PBS/BBC/NHK Documentary Superfish
- Billfishes of the World - FAO
Template:Meat-stub
Template:Fish-stub
Credits
New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:
The history of this article since it was imported to New World Encyclopedia:
Note: Some restrictions may apply to use of individual images which are separately licensed.
