Auxis rochei

Osteichthyes Scombridae Genus Auxis Auxis rochei
Bullet tuna BLT
37.5 cm TL
Characteristic features:
Colour:

Bluish black to purple above, silver below. Scaleless corselet area containing ~15 vertical dark bars behind first dorsal fin.

Size:

Up to 50 cm TL (smaller than Auxis thazard) and up to 1.84 kg in weight.1

Distribution:

Circumglobal in warm waters.

View FAO distribution map

Habitat:

Inshore pelagic, found from the surface to 200 m depth.

Biology:

Mostly eats small fishes, particularly clupeids, and also squid, crustaceans and zooplankton such as crab and stomatopod larvae. Highly migratory forming same and multi-species schools. Maturity varies by region, length at 50% maturity for both sexes is estimated to be 24 cm FL in India and 18.8 cm FL in the Philippines.2, 3 Age of first maturity in Japan is 1.25 years.4 Auxis rochei is a multiple spawner producing between 31,000–162,800 eggs per spawning depending on the size of the fish. Eggs are pelagic and considered an important part of the food web due to their high abundance. Maximum age is estimated at 5 years.5

Indonesian fisheries:

No dedicated fishery for Auxis rochei exists. Auxis rochei are caught with other species using lift nets, purse seines, shore seines, pole-and-line and by trolling.

Similar species:

Auxis thazard
Frigate tuna

Auxis thazard

Auxis thazard differs in having a wider posterior end of corselet of 10–15 scales wide under origin of second dorsal fin (vs. 1–5 scales); bars on dorsal scaleless area oblique to nearly horizontal (vs. more vertical); dorsal scaleless area longer, extends anterior of pectoral-fin tip (vs. shorter, extending posterior of pectoral-fin tip) and 36–42 gill rakers on first gill arch (vs. 43–48).

to Auxis thazard

Euthynnus affinis
Mackerel tuna

Euthynnus affinis

Euthynnus affinis differs in usually having ~3 black spots present between pectoral- and pelvic-fin bases (vs. none); a narrow inter-dorsal space (vs. wide) and 29–34 gill rakers on the first gill arch (vs. 43–48).

to Euthynnus affinis

Katsuwonus pelamis
Skipjack tuna

Katsuwonus pelamis

Katsuwonus pelamis differs in having 4–6 dark, longitudinal stripes on belly (vs. none); a narrow inter-dorsal space (vs. wide); interpelvic process 2 flaps (vs. single, large) and 53–63 gill rakers on the first gill arch (vs. 43–48).

to Katsuwonus pelamis

Sarda orientalis
Striped bonito

Sarda orientalis

Sarda orientalis differs in having a tongue without ridges or teeth (vs. 2 longitudinal ridges); a narrow interdorsal space (vs. wide); 5–11 narrow dark stripes on upper sides (vs. ~15 vertical dark bars in scaleless corselet area) and 8–13 gill rakers on the first gill arch (vs. 43–48).

to Sarda orientalis

Thunnus spp.
True tunas

Thunnus alalunga
Thunnus alalunga

Thunnus spp. differ in having an interpelvic process of 2 short flaps (vs. single, large); a body covered in small scales behind corselet (vs. a dorsal scaleless area) and a narrow interdorsal space (vs. wide).

to Thunnus spp.
Internal links:


Auxis rochei quiz

External links:
References:
  1. IGFA. IGFA world record game fishes. International Game Fish Association Dania Beach, Florida. 2011;
  2. Collette BB, Cole K. Reproduction and development in epipelagic fishes. Reproduction and sexuality in marine fishes: patterns and processes University of California Press, Berkeley. 2010;21–63.
  3. Muthiah C. Maturation and spawning of Euthynnus affinis, Auxis thazard and Auxis rochei in the Mangalore inshore area during 1979-82. CMFRI Bulletin. 1985;36:71–85.
  4. Niiya Y. Age, growth, maturation and life of bullet tuna Auxis rochei in the Pacific waters off Kochi prefecture [Japan]. Bulletin of the Japanese Society of Scientific Fisheries (Japan). 2001;
  5. Jasmine S, Rohit P, Abdussamad EM, Koya KP, Joshi KK, Kemparaju S, et al. Biology and fishery of the bullet tuna, Auxis rochei (Risso, 1810) in Indian waters. Indian Journal of Fisheries. 2013;60(2):13–20.