Torpedo Scad

The torpedo scad (Megalaspis cordyla), commonly referred to as the hardtail scad, finny scad, finletted mackerel scad, or cordyla scad, is a species of moderately large marine fish within the Carangidae family, which includes jacks and horse mackerels. This species is prevalent across the tropical Indo-Pacific region, from 🇿🇦 South Africa to 🇹🇴 Tonga, extending north to 🇯🇵 Japan and south to 🇦🇺 Australia. As a pelagic, schooling fish, the torpedo scad primarily inhabits the surface layers of both coastal and open ocean waters. It is distinguished by its characteristic torpedo-shaped body and a series of detached finlets located at the posterior of both the dorsal and anal fins. The largest individual recorded reached 80 cm in length and weighed 4 kg, though more common sizes are typically less than 40 cm. The species is predatory, consuming various fish, cephalopods, and crustaceans through active hunting and filter feeding, with fish remaining the primary dietary component across all size classes.

Sexual maturity in torpedo scad is reached at 22 cm in females and 26.4 cm in males, with spawning predominantly occurring from March to July in 🇮🇳 India, where extensive research on larval growth and morphometrics has been conducted. This species holds considerable economic importance to fisheries across the Indo-Pacific, notably in 🇮🇳 India. Data excluding 🇮🇳 India indicate that annual catches have increased from 70,000 tonnes in 1997 to 107,000 tonnes in 2007, with 🇮🇩 Indonesia and 🇲🇾 Malaysia being major harvesters. Although caught by anglers, the torpedo scad is often considered of low culinary value and is occasionally used as bait.

Morphologically, the torpedo scad exhibits an elongate and subcylindrical body form, compressing significantly toward the caudal region, featuring a marked median keel on the caudal peduncle. Both the dorsal and anal fins exhibit separate structures, with variations in their fin structures such as spines and soft rays. The lateral line is prominently arched over a short section anteriorly. Notable features include large scutes in the straight section of the lateral line and an adipose eyelid almost covering the eye. The dental structures consist of villiform teeth with some enlarged teeth located in the upper jaw. Additionally, there are 26 to 32 gill rakers and 24 vertebrae reported.

Additional insights into the olfactory and hypothalamo-neurosecretory systems have been extensively documented within 🇮🇳 Indian scientific literature. A deformity report on an individual fish indicated survivability beyond maturity despite such deformities.

The coloration of the torpedo scad is predominantly bluish-grey to green dorsally, transitioning to silvery white ventrally, with pale to yellow dorsal and anal fins. The caudal fin displays darker pigmentation along its edges, and a large black spot is present on the operculum.

The geographical distribution of the torpedo scad spans tropical and subtropical waters of the 🇮🇳 Indian and western 🌊 Pacific Oceans. Notably, its range includes diverse locales from East Africa to the 🌊 Persian Gulf, encompassing regions such as the 🇲🇻 Maldives, 🇸🇨 Seychelles, and 🇲🇬 Madagascar. Additional occurrences include Asian coastlines through to 🇨🇳 China and 🇰🇷 South Korea, with abundant populations throughout the central Indo-Pacific and 🇮🇩 Indonesian Archipelago. Records extend to areas off 🇦🇺 Australia and various eastern Pacific islands like 🇼🇸 Samoa and 🇹🇴 Tonga.

Characterized as a schooling, pelagic species, the torpedo scad is prevalent in both offshore and protected inshore environments; however, it demonstrates intolerance to turbid waters and is rarely found in estuarine zones. Seasonally, its distribution can shift southward following warmer ocean currents.

The torpedo scad holds significant commercial value in Asian fisheries, with comprehensive research on its biology and ecology published, predominantly in 🇮🇳 Indian journals. It is a versatile predator utilizing both active and passive feeding methods to capture prey ranging from fish and cephalopods to smaller crustaceans and molluscs, with dietary shifts observed as the species matures. Predators of torpedo scad include several types of drumming fish and requiem sharks. Spawning patterns indicate peaks in larval abundance from March to July, with a notable peak occurring in June within 🇮🇳 Indian waters. Understanding the life cycle and growth dynamics of the torpedo scad has informed fisheries management, advocating for the capture of individuals only after reaching a minimum size threshold for sustainability purposes.