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Almaco Jacks, Seriola rivoliana

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Description & Behavior

Almaco jacks, Seriola rivoliana (Valenciennes, 1833), aka almaco amberjacks, ambers, amberjacks, crevalles, deep-water amberjacks, European amberjacks, falcate amberjacks, greater amberjacks, highfin amberjacks, jacks, longfin kingfishes, longfin yellowtails, rock salmons, silvercoat jacks, and yellow kingfishes, are a dusky-colored amberjack with a faint amber or olive stripe running down their sides. Their body and lower fins are generally dark brown or dark blueish green, and their lighter-colored belly may look brassy or even lavender. Almaco jack's dorsal and anal fins are high and elongated, with deeply sickle-shaped outer edges. The nuchal (back of the neck or back) bar in adults is dark-colored, as are their fins, excepting their pelvic fins, which are white on their ventral (under) side. Almaco jacks typically have less elongated, more flattened bodies than other species of jacks (140 species of jack have been identified to date). Adults can reach 1.6 m and usually weigh 6.8-14 kg, though they may exceed 59 kg. Almaco jacks are known for their stamina and strength, making them a prized target of deep-sea sport fishermen. Like other jacks, Almaco jacks like to remove parasites from their skin by rubbing themselves on the rough skin of passing sharks—and occasionally, human divers they mistake for sharks.

World Range & Habitat

Almaco jacks, Seriola rivoliana, are a wide-ranging pelagic species that usually lives in small schools on outer reef slopes or offshore banks at depths ranging from 5-160 m. Adults are largely nomadic. Almaco jacks are more oceanic than most other species of jacks, though they do tend to frequent rocks, wrecks and offshore oil and gas platforms. The species inhabits both tropical and subtropical waters. In the Indian Ocean and West Pacific, the Almaco jack can be found off the coast of Africa from Kenya to South Africa. The species has also been spotted off the Mariana, Wake, Ryuku, and Kermadee Islands, as well as New Caledonia. In the Eastern Pacific, the almaco jack covers an area stretching from southern California to Peru, including the Galapagos Islands. The species can also be found in the Atlantic, particularly from Cape Cod in the United States to northern Argentina, though it is rarely seen north of the Carolinas. Its presence has not been fully documented in the eastern Atlantic, though some Almaco jacks have been seen at Lampedusa Island in the Mediterranean and, rarely, off the coast of England. Young Almaco jacks sometimes live in the branching algae beds known as Sargassum or around other floating objects.

Feeding Behavior (Ecology)

Almaco jacks, Seriola rivoliana, are fast-swimming predators that feed both day and night. They eat mainly fishes, particularly small bony fishes (baitfish), but also invertebrates such as small squid.

Life History

Little is known about the reproductive habits of Almaco jacks, though scientists expect that its behavior is similar to that of greater amberjacks. Spawning occurs offshore at various times throughout the spring, summer and fall, depending on latitude and water temperature.

Conservation Status & Comments

Almaco jacks caught near coral reefs may cause ciguatera poisoning, a stomach irritation that is sometimes fatal.

Resilience to fishing pressure: Low, minimum population doubling time 4.5 - 14 years
Extinction vulnerability to fishing: High to very high vulnerability (72 of 100)

References & Further Research

Florida Fish and Wildlife Conservation Commission - Marine Fisheries

Research Seriola rivoliana » Barcode of Life ~ BioOne ~ Biodiversity Heritage Library ~ CITES ~ Cornell Macaulay Library [audio / video] ~ Encyclopedia of Life (EOL) ~ ESA Online Journals ~ FishBase ~ Florida Museum of Natural History Ichthyology Department ~ GBIF ~ Google Scholar ~ ITIS ~ IUCN RedList (Threatened Status) ~ Marine Species Identification Portal ~ NCBI (PubMed, GenBank, etc.) ~ Ocean Biogeographic Information System ~ PLOS ~ SIRIS ~ Tree of Life Web Project ~ UNEP-WCMC Species Database ~ WoRMS

Search for Almaco Jacks » ARKive ~ ~ Bing ~ dmoz ~ Flickr ~ Google ~ NatureFootage ~ Picsearch ~ Wikipedia ~ Yahoo! Images ~ YouTube

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