Fisheries and aquaculture are confronted with continuing problems such as climate change, growing human populations, low income of small scale fishers and fish farmers, and competitive production and trading conditions. People should be confronting and discussing the challenges in order to come up with solutions on how we can respond; and the community should be resilient and adaptive in combatting the challenges. We cannot immediately solve some problems, such as overfishing, illegal fishing, depletion of marine resources, as they have deep root causes, but we are learning how to address them. Governments do their best to manage fishery resources to meet these challenges. Decision makers and the public also need to continually listen to new information so that they are equipped with knowledge for sustaining marine and aquaculture resources and protecting people who depend on them for nutrition, livelihood and business. Research is an important information gathering tool that contributes to policy and decision-making. The Asian Fisheries Society and its partners are taking a lead in making new information accessible through its platform AsiaPacific-FishWatch providing essential information on fish harvested or farmed for food in Asia-Pacific. I am pleased that AsiaPacific-FishWatch gives attention in its profiles and posts to the critical social, economic and market character of the value chains. The Asian Fisheries Society emphasises equally social and economic knowledge and biological, physical and technical knowledge.

Prof. Alice Joan G. Ferrer, PhD, President, Asian Fisheries Society

 
 
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ASIAPACIFIC-FISHWATCH

DESCRIPTION

The yellowfin tuna is a large, elongate fish with a round and tapered body. Its body is deepest at the first dorsal fin. Some large specimens have very long second dorsal and anal fins, which can be more than 20% of fork length (FL). The pectoral fins are moderately long, usually reaching beyond the origin of the second dorsal fin but not beyond the end of its base. The back is metallic dark blue in colour, changing to yellow and then to silver on belly, which is frequently crossed, at juvenile sizes by about 20 broken, nearly vertical lines. These lines disappear in adults. The second dorsal and anal fins, and dorsal and anal finlets, are bright yellow. The finlets may have a narrow black border. There is a strong lateral keel on the caudal peduncle. Yellowfin tuna has 26-34 gill rakers on the first gill arch.

Yellowfin tuna has a swim bladder. When inflated, the swimbladder is about half the length of the body cavity whereas, in bigeye tuna, the swimbladder reaches most of the length of the body cavity.

Yellowfin tuna is similar in appearance to bigeye tuna, but can be distinguished using several external features (body markings, body shape, head and eye shape, pectoral and caudal fin characteristics, finlet coloration) and internal features (liver shape, swimbladder size). Juveniles of yellowfin and bigeye tuna are more difficult to distinguish than are adults.

ECOSYSTEM ROLE

Together with the other species of tropical tuna, yellowfin tuna is near the top of the pelagic food chain. Tunas typically follow the daily vertical movement of their preferred prey (micronekton), moving to deeper habitats during the day and to shallower habitats at night. Yellowfin tuna spends most of its foraging time above the thermocline. As it grows, yellowfin tuna is able to capture larger prey, within the limits of the sizes available. As an oceanic predator spending considerable time in the surface layers, especially when young, yellowfin tuna also consumes prey (eggs, invertebrate and fish plankton) exported from reef ecosystems.

Predators of yellowfin tuna include other tunas, including other yellowfin tuna, pelagic sharks, sailfish, marlins, and toothed whales including dolphins.

HABITAT AND DISTRIBUTION

Yellowfin tuna mainly inhabit tropical and subtropical waters of the Atlantic, Indian and Pacific oceans, but can occur up to 40oN and 40oS. It is found predominately in tropical coastal and open ocean ecoregions, in waters from the surface to the mixed layer depth that varies with place and season. Yellowfin tuna does not occur over shallow coastal shelves (ocean depths less than about 50 m). [See slide show for yellowfin tuna distribution map]. In the Pacific, most of the population occurs from 20oN to 20oS.

Yellowfin tuna tolerates a wide range of environmental conditions. Water temperature and oxygen levels have a major influence on the habitats yellowfin tuna occupies. Like other tuna, the blood circulation of yellowfin has a heat exchanger system that can sustain muscle temperature significantly above that of the water. This specialized anatomy gives yellowfin tuna enhanced swimming efficiency and the ability to live within a relatively wide range of temperatures. Yellowfin tuna regulates its body temperature in response to muscle temperature changes, moving into cooler or warmer waters as required. As a result, yellowfin can feed in both sunlit surface waters and in deeper, cooler nutrient-rich layers of the ocean.

Yellowfin tuna have been found in water temperatures of 18o to 31oC, but most commonly live between 20o to 30oC. Yellowfin tuna spend less than 10% of their time at depths where oxygen (O2) levels are < 4.3 mg/l (3.3 mg/l, 65% saturation). As a result of temperature preferences and tolerances, juvenile and adult yellowfin usually remain in depths in which temperatures are within 8oC of that of the surface water although occasionally they dive to around 1000 m. In the Indian Ocean, the main swimming depth for adult yellowfin tuna caught by longline is from 80 m to 200 m.

Yellowfin tuna can be highly migratory, and long-distance movements of thousands of nautical miles have been recorded. However, the vast majority of recorded movements of tagged yellowfin tuna have been much shorter. For example, the median lifetime displacement for yellowfin tuna in the Western and Central Pacific Ocean (WCPO) is 337-380 nm.

Although tagging data indicate that yellowfin tuna in the WCPO are a single stock, sub-regional biological differences are possible and need further investigation. In the IO, tagging data support the assumption that yellowfin tuna comprises a single stock.

GROWTH, REPRODUCTION AND DIET

Yellowfin tuna growth is complex, and goes through several stages over its life. A juvenile yellowfin tuna grows quickly to about 40 cm FL and is first caught in surface commercial fisheries when only several months old. Growth slows between 40 and 70 cm and then accelerates again between 70 and 100 cm FL, probably during sexual maturation. Older fish live in deeper colder waters. Growth rate plateaus and declines with size. Young yellowfin tuna may grow more slowly in the equatorial waters of Indonesia and the Philippines than in the wider area of the Western and Central Pacific Ocean. The estimated average maximum size is 180 cm and 100 kg. Tag-and-release information, indicates that yellowfin live for at least six years.

Yellowfin tuna reaches sexual maturity at a length of 95-120 cm FL and an age of 2 to 3.5 years. However, in exceptional circumstances, it can become mature at 50- 60 cm FL and an age of 12 -15 months. Spawning can take place all year-round, but is most frequent during the summer months in each hemisphere. Yellowfin tuna are multiple batch (serial) spawners, i.e. they spawn eggs and sperm into the water column almost every day over the spawning period. Average batch fecundity (egg production per spawning event) is 2.2 million in the Western Pacific.

Extensive sampling of tuna stomachs has shown that the diet of yellowfin tuna is diverse, comprising a variety of surface-dwelling and deeper-dwelling fish species, pelagic crustaceans and squid. The diet also changes with age. In the Western and Central Pacific Ocean, juvenile yellowfin tuna (< 45 cm) consume mainly anchovies (Engraulidae), other small surface-dwelling fish (including reef-associated fish during their pelagic phase) and planktonic crustaceans. Subadult (45-120 cm) and adult (>120 cm) yellowfin prey on scombrid fishes (including juvenile skipjack tuna), pelagic-stages of reef fish, squid and deeper-dwelling fish.

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Guide to Further Reading

Note: Details of all sources are given below in References.

For description of yellowfin tuna, see Bruce Collette (2001). For the most comprehensive guides and handbooks to the identification of yellowfin and bigeye tuna, from fresh to frozen and damaged, see the Secretariat for the Pacific Community FAME Digital Library, and enter "yellowfin" AND "David Itano" (author) into the search boxes to obtain the guides, many in several languages; also see David Itano (2005). See also for Kurt Schaefer (1999) on physical differences, including extent of swim bladder.

For ecosystem role, with an emphasis on the Western and Central Pacific Ocean (WCPO), see John Sibert and colleagues (2006) and Valerie Allain and colleagues (2012); and, on predators, FishBase.

For habitat and distribution, see Gabriel Reygondeau and colleagues (2012) for ecoregions, Makoto Peter Miyake and colleagues (2010), and FAO yellowfin tuna distribution map (link). For stock structure, see WCPFC (2012) and, for IO, Adam Langley and colleagues (2009).

For environmental and habitat information, see Paul Sund and colleagues (1981), and Patrick Lehodey and colleagues (2011). For temperature, oxygen, and depth distribution information, see Richard Brill and colleagues (1999), Li Ming Song and colleagues (2008), and Kurt Schaefer and colleagues (2011). For WCPO yellowfin tuna displacements, see John Sibert and John Hampton (2003).

For growth, see Alain Fonteneau and Didier Gascuel (2008), Alain Fonteneau and Emmanuel Chassot (2013), Adam Langley and colleagues (2011), Patrick Lehodey and Bruno Leroy (1999).

For reproduction, see Kurt Schaefer (1996, 1998), Patrick Lehodey and Bruno Leroy (1999), David Itano (2000) For diet, in WCPO see Arnaud Bertrand and colleagues (2002), Valerie Allain and colleagues (2012); in Indian Ocean see Michel Potier and colleagues (2004); and, more generally, FishBase.

References

  • Allain, V, E Fernandez, SD Hoyle, S Caillot, J Jurado-Molina, S Andréfouët, & SJ Nicol. 2012. Interaction between coastal and oceanic ecosystems of the western and central Pacific Ocean through predator-prey relationship studies. PLoS ONE. 7 (5)
  • Bertrand, A, F-X Bard & E Josse. 2002. Tuna food habits related to the micronekton distribution in French Polynesia. Marine Biology 140:1023-1037.
  • Brill, RW, BA Block, CH Boggs, KA Bigelow, EV Freund & DJ Marcinek. 1999. Horizontal movements and depth distribution of large adult yellowfin tuna (Thunnus albacares) near the Hawaiian Islands, recorded using ultrasonic telemetry: implications for the physiological ecology of pelagic fishes. Marine Biology 133:395-408.
  • Collette, BB. 2001. Tunas (also, albacore, bonitos, mackerels, seerfishes, and wahoo). Pp 3721-3756, in K.E. Carpenter & V.H. Niem (eds), FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Vol. 6: bony fishes part 4 (Labridae to Latimeriidae), estuarine crocodiles, sea turtles, sea snakes and marine mammals. Rome, FAO.
  • Fonteneau, A. and D. Gascuel. 2008. Growth rates and apparent growth curves, for yellowfin, skipjack and bigeye tagged and recovered in the Indian Ocean during the IOTTP. IOTC-2008-WPTDA-08.
  • Fonteneau, A. and E. Chassot. 2013. An Overview of Yellowfin Tuna Growth in the Atlantic Ocean: Von Bertalanffy or Multistanza Growth? ICCAT, SCRS/2012/045 Collect. Vol. Sci. Pap. ICCAT, 69(5):2059-2075.
  • Itano, DG. 2000. The reproductive biology of yellowfin tuna (Thunnus albacares) in Hawaiian waters and the western tropical Pacific Ocean: Project summary. SOEST 00-01, JIMAR Contribution 00-328.
  • Itano, D. 2005. A handbook for the identification of yellowfin and bigeye tunas in fresh condition (v2). Western and Central Fisheries Commission. Fishing Technology Working Group. December 2005. 25 p.
  • Langley, A, M Herrera, J-P Hallier & J Million. 2009. Stock assessment of yellowfin tuna in the Indian Ocean using MULTIFAN-CL. Indian Ocean Tuna Commission, 11th Session of the Working Party on Tropical Tunas, 10-23 October 2009, Kenya. Working paper 10. 66p.
  • Langley, A, S Hoyle, & J Hampton. 2011. Stock assessment of yellowfin tuna in the Western Central Pacific Ocean. Western & Central Pacific Fisheries Commission 7th Scientific Committee Regular Session, 9-17 August 2011, Pohnpei, Federated States of Micronesia, Paper SA-WP-03 (Revision 1-03 August 2011). 135 p.
  • Lehodey, P & Leroy, B. 1999. Age and growth of yellowfin tuna (Thunnus albacares) from the Western and Central Pacific Ocean as indicated by daily growth increments and tagging data. Working Paper YFT-2, Standing Committee on Tuna and Billfish, 16-23 June, 1999, Tahiti.
  • Lehodey, P, J Hampton, RW Brill, S Nicol, I Senina, B Calmettes, HO Pörtner, L Bopp, T Ilyina, JD Bell, & J Sibert. 2011. Vulnerability of oceanic fisheries in the tropical Pacific to climate change. Pp 433-492, in JD Bell, JE Johnson & AJ Hobday (eds), Vulnerability of Tropical Pacific Fisheries and Aquaculture to Climate Change. Secretariat of the Pacific Community, Noumea, New Caledonia.
  • Miyake, MP, P Guillotreau, CH Sun, & G Ishimura. 2010. Recent developments in the tuna industry: stocks, fisheries, management, processing, trade and markets. FAO Fisheries and Aquaculture Technical Paper. No.543. Rome, FAO. 125 p.
  • Potier, M, F Marsac, V Lucas, R Sabatié, J-P Hallier & F Ménard. 2004. Feeding Partitioning among Tuna Taken in Surface and Mid-water Layers: The Case of Yellowfin (Thunnus albacares) and Bigeye (T. obesus) in the Western Tropical Indian Ocean. Western Indian Ocean Journal of Marine Science 3(1):51-62.
  • Reygondeau, G, O Maury, G Beaugrand, JM Fromentin, A Fonteneau & P Cury. 2012. Biogeography of tuna and billfish communities. Journal of Biogeography, 39:114-129.
  • Schaefer, K. 1996. Spawning time, frequency, and batch fecundity of yellowfin tuna, Thunnus albacares, near Clipperton Atoll in the eastern Pacific Ocean. Fish. Bull. 94:98-112.
  • Schaefer, K. 1998. Reproductive biology of yellowfin tuna (Thunnus albacares) in the eastern Pacific Ocean. Inter-Am.Trop. Tuna Comm. Bull. 21:205-221.
  • Schaefer, KM. 1999. Comparative study of some morphological features of yellowfin (Thunnus albacares) and bigeye (Thunnus obesus) tunas. Bulletin/Inter.-American Tropical Tuna Commission, 21:491-525.
  • Schaefer, KM, DW Fuller, & BA Block. 2011. Movement, behaviour and habitat utilization of yellowfin tuna (Thunnus albacares) in the Pacific Ocean off Baja California, Mexico, determined from archival tag data analyses, including unscented Kalman filtering. Fisheries Research 112 (2011): 22-37.
  • Sibert, J & J Hampton. 2003. Mobility of tropical tunas and the implications for fisheries management. Marine Policy 27:87-95.
  • Sibert, J, J Hampton, P Kleiber & M Maunder. 2006. Biomass, size, and trophic status of top predators in the Pacific Ocean. Science 314:1773-1776.
  • Song, LM, Y Zhang, LX Xu, WX Jiang & JQ Wang. 2008. Environmental preferences of longlining for yellowfin tuna (Thunnus albacares) in the tropical high seas of the Indian Ocean. Fisheries Oceanography 17:239-253.
  • Sund, PN, M Blackburn M & F Williams. 1981. Tunas and their environment in the Pacific Ocean: A review. Oceanography Marine Biology: An Annual Review 19, 443-512.
  • WCPFC (Western and Central Pacific Fisheries Commission). 2012. Summary Report of the Scientific Committee, the Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean. 7th Regular Session, 9-17 August 2011, Kolonia, Pohnpei, Federated States of Micronesia. 211p.

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