Senegal jack
(Caranx senegallus)

The Senegal jack (Caranx senegallus), also known as the African jack, is a species of large marine fish classified in the jack family Carangidae.

The species is distributed through the tropical waters of the eastern Atlantic Ocean, ranging along the west African coast from Angola in the south to Mauritania in the north.

It can be distinguished from co-occurring relatives by its longer dorsal fin lobe, as well as a host of other anatomical features.

The Senegal jack grows to a known maximum length of 1 m.

It is a coastal species, known to live semi-pelagically, inhabiting both the sea floor and surface waters to depths of around 200 m.

The Senegal jack is a predatory species, taking fish, crabs and shrimps as its main prey items. The species reaches sexual maturity at 21 cm in females and 24 cm in males, with spawning occurring in two periods; February to April and September to November. The species is of minor importance to fisheries, and is not discriminated from other jacks in catch statistics. It is taken by trawls, seines and hook and line, and sold fresh or preserved.

It has a body shape typical of most other species of Caranx, with a moderately compressed ovate form and blunt pointed snout. The dorsal profile is slightly more convex than the ventral profile. The dorsal fin is in two distinct sections, the first consisting of 8 spines while the second has 1 spine and 20 or 21 soft rays. The anal fin consists of 2 detached spines anteriorly followed by 1 spine and 17 or 18 soft rays.

Both the anal and dorsal fins are elongate, with the dorsal lobe being over twice the length of the head. The pectoral fin is falcate, and also longer than the head.

The lateral line has a short, strong anterior arch, with 40 to 45 scutes on the straight posterior section. Above and below the terminus of the lateral line on the caudal peduncle are bilateral caudal keels.

The rest of the body is covered in small cycloid scales, with the exception of the breast which is naked.

The Senegal jacks eye has a weakly developed adipose eyelid, with the end of the upper jaw extending to directly under the middle of the eye. The upper jaw contains an inner band of villiform teeth with an irregular series of outer canines, while the lower jaw contains only a band of villiform teeth.

The species has 38 to 42 gill rakers and 24 vertebrae.

The Senegal jack is a green to blue colour dorsally, fading to a silvery white below. The fins are hyaline to grey, with the pectoral fin and anal fin lobe having a pale yellow tinge. The species has a black spot on the upper opercular margin.