Diplodus argenteus

Diplodus argenteus, the silver porgy, is an ocean-going species of sparid fish (seabream/porgies). It is also called the South American silver porgy and the white bream in Uruguay, plus the silver seabream and the sargo, though the latter three names are also used for other fish species as well.

Diplodus argenteus
Diplodus argenteus photographed on a reef near Cabo Frio, Brazil
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Spariformes
Family:	Sparidae
Genus:	Diplodus
Species:	D. argenteus
Binomial name
Diplodus argenteus (Valenciennes, 1830)
Synonyms
Sargus argenteus Valenciennes, 1830 Sparus sargo Larrañaga, 1923

Taxonomy and naming

The silver porgy was originally described in 1830 by the French zoologist Achille Valenciennes as Sargus argenteus, but it was later moved from the genus Sargus into Diplodus. Another binomial name, Sparus sargo, was erected by Dámaso Antonio Larrañaga in 1923 to describe fishes that are now considered to be silver porgies as well, meaning that Sparus sargo is considered a junior synonym for D. argenteus.

Etymology

The genus name, Diplodus, means "double toothed", a description which was not well-explained, but may have been done in reference to the species' two types of teeth: incisor-like and molar-like, or to the double incisor-like tooth shape common to this genus. The species name argenteus comes from the Latin word for silver, which is a reference to the fish's coloration, rather than its origin near Argentina. Coincidentally, Argentina's name is also derived from the Latin word for silver.

Description

As its name suggests, this D. argenteus' silvery coloration (often with a yellowish tint on the scales and fins) is a significant characteristic of its appearance. In addition to its main coloring, there are nine dark, narrow bars that can be faintly visible on the anterior portion of its body (especially in younger individuals, as they fade with age), there is also a large, black blotch on the caudal peduncle, and the opercular membrane is also very dark in color. The silver porgy's dorsal fin is made up of 12 spines, and 13–15 soft rays; it's anal fin is consists of only 3 spines, but 12–14 soft rays. Mature silver porgies achieve about 20–23 cm (7.9–9.1 in) in length, while the maximum known length for this species is 37.8 cm (1.24 ft) in length.

Distribution and habitat

The silver porgy is known primarily from the western Atlantic Ocean, where it can be found in the waters of southern Florida as well as the Antilles and Bahamas. Along the coast of South America, it is known from coasts of Colombia and Venezuela to Argentina – as far south as the coast of northern Patagonia. They are also found in the Bay of Campeche, which is part of the Gulf of Mexico.

Seagrass beds such as this one in the Caribbean Sea often inhabited by subadult silver porgies.

Adult silver porgies usually inhabit clear but turbulent waters over rocky or coral bottoms, especially on unsheltered coasts that are heavily affected by surf. Juveniles, on the other hand, can be found in much shallower water, such as in pools between rocks, though mid-sized individuals up to 10 cm (3.9 in) can be also found in beds of seagrass from the genus Thalassia.

Biology

Silver porgies eat mostly shellfish especially crustaceans and mollusks, however the remains of algae and polychaete worms have also been found in the stomachs of specimens collected from the Brazilian coast. Variation in diet does occur as the fish grows, mostly in relation to mouth size, as different prey species can only be consumed by individuals large enough to catch them.

Relationship with humans

The silver porgy is fished commercially, but only traded locally. Able to be caught via angling or through trapping, it makes up a major portion of the catch in the Cabo Frio region of Brazil, but is generally caught incidentally, and is even reported rare from fisheries in other parts of its range such as Cuba. Catches are generally very small and come from Argentina, Brazil, and Uruguay, though fishing for this species off the United States East Coast and Brazil once dominated the silver porgy catch for most of the late-20th century.

Because of its habitat and distribution, this species is often encountered by recreational SCUBA divers and snorklers. Despite its fairly high probability of being encountered in certain ecosystems, the silver porgy seldom approaches divers and generally moves away from them when approached.

References

1. Carpenter, K.E.; Russell, B. (2014). "Diplodus argenteus". IUCN Red List of Threatened Species. 2014: e.T170154A1283454. doi:10.2305/IUCN.UK.2014-3.RLTS.T170154A1283454.en. Retrieved 5 October 2024.
2. Chute, W. 1953. Guide to the John G. Shedd Aquarium. 4th edition, 4th printing. Pg. 114–115
3. Nión, H., C. Ríos and P. Meneses, 2002. Peces del Uruguay: Lista sistemática y nombres comunes. Montevideo, DINARA, Infopesca.
4. Fricke, Ronald; Golani, Daniel & Appelbaum-Golani, Brenda (2016). "Diplodus levantinus (Teleostei: Sparidae), a new species of sea bream from the southeastern Mediterranean Sea of Israel, with a checklist and a key to the species of the Diplodus sargus species group". Scientia Marina. 80 (3): 305–320. doi:10.3989/scimar.04414.22B.
5. Cuvier, G. and A. Valenciennes 1830 (Sept.) Histoire naturelle des poissons. Tome Sixième. Livre sixième. Partie I. Des Sparoïdes; Partie II. Des Ménides. v. 6: i–xxiv + 6 pp. + 1–559, Pls. 141–169. [Valenciennes is author of pp. 1–425, 493–559; Cuvier 426–491. i–xviii + 1–470 in Strasbourg ed.]
6. Larrañaga, D. A. 1923 Escritos de Don Dámaso Antonio Larrañaga. Los Publica el Instituto Histórico y Geográphico del Uruguay. Edición Nacional. v. 2: 1–512 [Atlas published in 1930. See also Devincenzi 1925
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10. Smith, C.L., 1997. National Audubon Society field guide to tropical marine fishes of the Caribbean, the Gulf of Mexico, Florida, the Bahamas, and Bermuda. Alfred A. Knopf, Inc., New York. 720 p.
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12. David, G.S.; Coutinho, R.; Quagio-Grassiotto, I. & Verani, J.R. (2005). "The reproductive biology of Diplodus argenteus (Sparidae) in the coastal upwelling system of Cabo Frio, Rio de Janeiro, Brazil". African Journal of Marine Science. 27 (2): 439–447. Bibcode:2005AfJMS..27..439D. doi:10.2989/18142320509504102.
13. Galvan, D. E.; Venerus, L. A.; Irigoyen, A. J.; Parma, A. M. & Gosztonyi, A. E. (2005). "Extension of the distributional range of the silver porgy, Diplodus argenteus (Valenciennes 1830), and the red porgy, Pagrus pagrus (Linnaeus 1758) (Sparidae) in northern Patagonia, south-western Atlantic". Journal of Applied Ichthyology. 21 (5): 444–447. Bibcode:2005JApIc..21..444G. doi:10.1111/j.1439-0426.2005.00621.x.
14. Randall, J.E. and R. Vergara, 1978. Sparidae. In W. Fischer (ed.) FAO species identification sheets for fishery purposes. Western Central Atlantic (Fishing Area 31). FAO, Rome. Vol. 5. pag.var.
15. Cervigón, F., 1993. Los peces marinos de Venezuela. Volume 2. Fundación Científica Los Roques, Caracas,Venezuela. 497 p.
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17. Dubiaski-Silva, J. & Masunari, S. (2006). "Ontogenetic and seasonal variation in the diet of marimbá, Diplodus argenteus (Valenciennes, 1830) (Pisces, Sparidae) associated with the beds of Sargassum cymosum C. Agardh, 1820 (Phaeophyta) at Ponta das Garoupas, Bombinhas, Santa Catarina". Journal of Coastal Research: 1190–1192. JSTOR 25741773.
18. Marques, Simone & Barreiros, João P. (2015). "Opportunistic feeding behavior of Diplodus argenteus (Perciformes, Sparidae): human-fish interaction in two rocky reefs from SE and S Brazil" (PDF). Pan-American Journal of Aquatic Sciences. 10 (1): 80–83. hdl:10400.3/3450.
19. "Global catches of South American silver porgy (Diplodus argenteus argenteus) by EEZ". www.seaaroundus.org. Sea Around Us. Retrieved September 14, 2024.
20. Humann, Paul & Deloach, Ned (2006). Reef Fish Identification Florida Caribbean Bahamas. New World Publications Inc. ISBN 1-878348-30-2.