Regalecus glesne
Oarfish
Collection Details
Specimens
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Records
Taxonomic Hierarchy
Actinopterygii (Ray-finned Fishes)
Lampridiformes
Regalecidae (Oarfishes)
Regalecus
Regalecus glesne (Oarfish)
Description
This species account was compiled from
Composite (multiple sources) (McEachran, J.D. and J.D. Fechhelm. Fishes of the Gulf of Mexico. University of Texas Press, Austin.)
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Characters
Very elongate and compressed body; very protrusible jaws; long dorsal fin; reduced or rudimentary caudal fin; short head; strongly concave dorsal profile anterior to dorsal fin; single nostril on each side of snout; toothless or small teeth at front of lower jaw; 7 gill rakers on epibranch and 36 on lower limb; short pectoral fin with 14 rays; dorsal fin originates anterior to center of eye with 10 to 12 elongated rays and 400 succeeding shorter rays; pelvic fin in adults consists of single elongate ray; caudal fin of juveniles has 4 free rays
Silvery with oblique dusky bars; head bluish; fins deep red
Distribution
Bermuda to Florida and the Gulf of Mexico
Habitat Associations
Tropical to warm temperate seas at lower epipelagic and mesopelagic depths
Biology
Squids, euphausid crustaceans, and fishes
About 8 m SL, with unconfirmed reports of specimens over twice this length
Cool-water, anti-tropical distribution, at latitudes greater than 15° (Ref. 92949). Oceanic and can live at great depths (Ref. 2850), but occasionally cast up on beaches (Ref. 9563). Large adults sometimes kill themselves by swimming out of the water onto beaches; occurrence of such strandings may be linked to certain areas, seasons or months and often in spates. With a unique adaptation of self-amputation (autotomy) of the posterior part of the body past the vent which may involve only the caudal fin (or one to a few small adjacent vertebrae) or as far anterior as just before the abdomen; apparently occurs several times during its lifetime (serial autotomy) but do not damage any vital organs and are usually survived except in strandings. All records over 1.5 m long have bodies shortened by autotomy and may exhibit a healed-over stump or "terminus"; still, many specimens found with fresh (with a ragged appearance very different from a healed termini) incomplete self-amputations of the posterior part of the body, notably not consistent with shark bites; the lost part is never regenerated. Species of this Regalecus attain lengths of 7-8 meters and this is well established by documented specimens. Oftentimes vertically suspended head-up in clear oceanic or inshore waters with the rays of the two dorsal fin crests usually extended vertically upwards while the pelvic fin rays may be horizontally spread outward and away from the body (Ref. 92949). This is hypothesized to be a feeding stance that visually allows the fish to spot the silhouette of its potential prey against the skylight (Ref. 49905). Feed on euphausiid crustaceans, small fishes and squid (Ref. 6738). Toothless protrusile jaws work to suction krill-laden water into its oro-branchial cavity and retained in the gullet by the long, spiny and bristly gill rakers (Ref. 92949). Occassionally associate in pairs (gender undocumented) but no record of group larger than three or of schooling behavior (Ref. 92949). Spawning occurs between July and December and larvae are encountered near the surface (Ref. 9337). Mature individuals spawn in the North Atlantic along the west coast of Florida and off the northern coast of America; in or near the Straits of Messina in the Mediterranean; in the South Pacific in the Catham Rise area of New Zealand and somewhere off the west coast of southern Australia (Ref. 92949). In Guinness Book of Records as longest bony fish (Ref. 6472). Also caught with encircling nets and marketed fresh (Ref. 9337). Reputed to be unpalatable because the flesh is tasteless or otherwise unappetizing (Ref. 92949). Underwater footage shows them slowly swimming vertically, head up, with a stiff body, only undulating the dorsal fin, and with photophores on their appendages. The mouth can be protruded for capturing prey (RF, pers. comm. 2013).
Reproductive mode: dioecism; fertilization: external; nonguarders (open water/substratum egg scatterers); parental care: none. Are broadcast spawners with no parental care for the young (Ref. 92949).
IUCN Red List Status: Least Concern (LC), assessed 2013-05-07. Resilience: Very low (Assuming tm>10; Fec = 139,000).
Phylogeny and Morphologically Similar Fishes
Distinguished from other species of the family by the combination of characters described
Commercial or Environmental Importance
Fisheries: minor commercial; gamefish.
References
Trunov 1982
Heemstra 1986c
Palmer 1986b
C. R. Robins et al. 1986
Breder, C.M. and D.E. Rosen (1966) Modes of reproduction in fishes. T.F.H. Publications, Neptune City, New Jersey. 941 p.
Bauchot, M.-L. (1987) Poissons osseux. p. 891-1421. In W. Fischer, M.L. Bauchot and M. Schneider (eds.) Fiches FAO d'identification pour les besoins de la pêche. (rev. 1). Méditerranée et mer Noire. Zone de pêche 37. Vol. II. Commission des Communautés Européennes and FAO, Rome.
Heemstra, P.C. (1986) Regalecidae. p. 403. In M.M. Smith and P.C. Heemstra (eds.) Smiths' sea fishes. Springer-Verlag, Berlin.
Quiniou, L. and J.-C. Quéro (1990) Regalecidae. p. 650-651. In J.C. Quero, J.C. Hureau, C. Karrer, A. Post and L. Saldanha (eds.) Check-list of the fishes of the eastern tropical Atlantic (CLOFETA). JNICT, Lisbon; SEI, Paris; and UNESCO, Paris. Vol. 2.
Fitch, J.E. and R.J. Lavenberg (1968) Deep-water teleostean fishes of California. California Natural History Guides:25. University of California Press, Berkeley and Los Angeles, California. 115 p.
Bauchot, M.-L. (1995) Regalecidae. Reyes de arenque. p. 1418. In W. Fischer, F. Krupp, W. Schneider, C. Sommer, K.E. Carpenter and V. Niem (eds.) Guia FAO para Identification de Especies para lo Fines de la Pesca. Pacifico Centro-Oriental. 3 Vols. FAO, Rome.
Pauly, D. and V. Christensen (1995) Primary production required to sustain global fisheries. Nature 374(6519):255-257.
Roberts, T.R. (2012) Systematics, biology, and distribution of the species of the oceanic oarfish genus Regalecus (Teleostei, Lampridiformes, Regalecidae). Paris: Mémoires du Muséum national d'histoire naturelle Tome 202, 268 p.
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