Dogtooth Tuna

Dogtooth tuna meat is whiter than that of other species of tuna, so they are widely sought after and highly prized both by commercial and sport fishermen.

Perception Channels: tactile ; chemical

Dogtooth tuna are susceptible to overfishing, and commercial net fishing is their biggest threat. Coupled with worldwide concern over dolphin free tuna, there is hope that this species can be protected with proper management. As yet, they have not made the ICUN red list and are not considered a threatened species.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: no special status

Ciguatera Fish Poisoning in humans is caused by the consumption of subtropical and tropical finfish. A naturally occurring toxin found in an algae (dinoflagellate) species common in the lower latitudes is the suspected cause. The occurrence of toxic fish is sporadic, and not all fish of a given species or locality will be toxic. Ciguatera poisoning is self-limiting: symptoms usually subside after a few days, are dismissed as seasickness or a hangover, and are therefore under reported.

Dogtooth tuna are a popular game fish. Many charter-fishing boats operate out of Australia and other parts of the south pacific providing a very lucrative business for their owners. They are also marketed commercially either canned or frozen.

Positive Impacts: food ; ecotourism

Dogtooth tuna feed upon shoaling fishes like herring (Clupea), sprats (Sprattus), mackerel (Scomber), whiting (Merlucciidae), cuttlefish (Sepia) and sometimes squid (Loligo).

Animal Foods: fish

Primary Diet: carnivore (Piscivore )

Dogtooth tuna (Gymnosarda unicolor) are found in the Indo West Pacific, from Australia (the Great Barrier Reef) to East Africa and the Red Sea, and in the waters off of the coast of Japan and the Philippines, New Guinea, Marquesas, Tahiti, Tuamotus, Pitcairn, and Oeno Islands.

Biogeographic Regions: oceanic islands (Native ); indian ocean (Native ); pacific ocean (Native )

Dogtooth tuna are typically pelagic, but are known to come inshore and are found around coral reefs and atolls at depths from 15m (50ft) to 45m (150ft). They prefer water temperatures between 21°C (70°F) and 26°C (80°F). They are migratory; their movements are linked to water temperatures and the fish they feed upon.

Habitat Regions: tropical ; saltwater or marine

Aquatic Biomes: pelagic ; reef ; coastal

Dogtooth tuna are members of the mackerel family. Distinguishing features include a streamlined body with a large head and a mouth that contains twenty sharp dog-like teeth per jaw. They have two dorsal fins; the first is spiny and large, and the second, right behind it is soft-rayed. The ventral fin is similar in size and shaped like the second dorsal. Nine spiny finlets stretch down the upper and lower tail section toward its crescent shaped tailfin. This species exhibits counter shading and has no scales. The dorsal surface is blue green, the sides are silver, and the belly is white. They swim constantly with their mouth open to force water through the gills because of a high oxygen requirement and great muscular activity. An unusual vessel system in the liver and tail provides counter-current temperature exchange, raising the body temperature 6°C to 12°C higher than the water temperature. They can reach speeds of up to 80 kph (50 mph). Dogtooth tuna's average weight is 15 to 20 kg (33 to 44 lbs). The spear fishing record is 55 kg and the all-tackle record is 131kg (288 lbs).

Range mass: 131 (high) kg.

Average mass: 15-20 kg.

Other Physical Features: endothermic ; ectothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike

Spawning takes place around December, January, and February. Dogtooth Tuna are non-guarders and are classified as open water substratum egg scatterers. The eggs are small and float near the surface, hatching within two days. Larvae are .635cm (0.25 inch) long and grow very quickly.

Breeding season: Spawning takes place from December to February.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous

Dorsal spines (total): 13 - 15; Dorsal soft rays (total): 12 - 14; Analspines: 0; Analsoft rays: 12 - 13; Vertebrae: 38

Oceanodromous. Migrating within oceans typically between spawning and different feeding areas, as tunas do. Migrations should be cyclical and predictable and cover more than 100 km.

This species is distinguished by the following characters: body elongate and moderately compressed; mouth fairly large, upper jaw reaching to middle of eye; 14 to 31 large, conical teeth on upper jaw, 10 to 24 on lower jaw; 2 patches of villiform teeth on upper surface of tongue; total gill rakers on first gill arch 11-14; D1 XIII-XV, its border almost straight, the second followed by 6-7 finlets, dorsal fins close together; anal fin followed by 6 finlets; pectoral fins with 25-28 rays; interpelvic process large and single; lateral line strongly undulating; body naked posterior to corselet except for lateral line, dorsal-fin base, and caudal keel; caudal peduncle slender, with a well-developed lateral keel between 2 smaller keels on each side. Colour of back and upper sides brilliant blue-black, lower sides and belly silvery; no lines, spots or other markings on body; anterior tip of first dorsal fin dark; other fins greyish (Ref. 9684).

An offshore species found mainly around coral reefs. Generally solitary or occur in small schools of six or less. Preys on small schooling fishes such as Decapterus, Caesio, Nasio, Cirrhilabrus, Pterocaesio and squids. Caught mainly by pole-and-line. Marketed canned and frozen (Ref. 9684, 48637). Adults may be ciguatoxic (Ref. 37816).

fisheries: minor commercial; gamefish: yes; price category: high; price reliability: reliable: based on ex-vessel price for this species

分布於印度-西中太平洋區，西起紅海、非洲東岸，北至日本，南至澳洲，以及大洋洲之馬貴斯、土木土及大溪地等群島。台灣主要產於東部海域。

一般漁法以流刺網或延繩釣捕獲。主要以加工製成罐頭為主，為次要經濟性魚種。

體紡錘形，橫切面近圓形，背緣和腹緣弧形隆起；尾柄細短，平扁，兩側各具一發達的中央隆起脊，尾鰭基部兩側另具2條小的側隆起脊。頭中大，稍側扁。吻尖突，大於眼徑。眼較小，位近頭的背緣。口中大，端位，斜裂；上下頜等長，上下頜齒具強大而尖銳齒1列，舌上有齒帶。第一鰓弓上之鰓耙數為12-17。體被細小圓鱗，頭部無鱗，胸部鱗較大，而形成胸甲；左右腹鰭間具1小鱗瓣；側線完全，沿背側平行延伸，伸達尾鰭基。第一背鰭具硬棘XIII-XV，與第二背鰭起點距離近，其後具7-9個離鰭；臀鰭與第二背鰭同形；尾鰭新月形。體背側青灰色，腹側淺色；體側無明顯的線紋或斑點。全世界此屬有4種，臺灣僅發現一種。

岩礁區巡游之魚類，通常單獨游動或集一小群。游泳快速，以魚類及甲殼類為食。

An offshore species found mainly around coral reefs at water temperatures ranging between 20 and 28°C. Generally solitary or occur in small schools of six or less individuals. Prey on small schooling fishes such as scads (@Decapterus@), @Caesio@, @Nasio@, @Cirrhilabrus@, @Pterocaesio@ and squids. Marketed canned and frozen (Ref. 9684).