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

 
 
  • Slide 1
  • Slide 2
  • Slide 3
  • Slide 4
  • Slide 5
  • Slide 6
  • Slide 7
  • Slide 8
  • Slide 9

ASIAPACIFIC-FISHWATCH

SPECIES IMPORTANCE

Bigeye tuna is of major commercial interest, caught primarily for sashimi (larger fish) and to a lesser extent, for canning (small fish).

Bigeye tuna occurs in the tropical and subtropical waters of the Atlantic, Indian and Pacific Oceans, but is absent from the Mediterranean Sea. Production is from all of these regions, Japan and the Republic of Korea being the major countries reporting catches.

In the Western and Central Pacific and Indian Oceans, bigeye tuna is targeted in the industrial and smaller scale tuna longlining fisheries and is taken also in non-targeted catches in the purse-seine and pole and line fisheries. Juvenile bigeye tuna caught in the purse seine fishery is either canned (although not invariably and may be diverted to fish meal, flakes etc. because of blood spots in the meat, and increasing traceability requirement for one species in the can as occasionally verified by DNA) and fresh in local markets; mature adults from the longline fishery generally are sold as sashimi or good quality steaks. Juvenile bigeye and yellowfin tuna are similar in appearance and as a result bigeye tuna is likely to be counted as yellowfin. Bigeye tuna catches, therefore, may be slightly underreported.

More than 80% of the world’s bigeye tuna is caught in the Indian and Pacific Oceans (Western and Central and Eastern areas). The catch was highest in the Western and Central Pacific Convention Area (around 150,000 t); followed by around 100,000 t in the Eastern Pacific Ocean area, and around 90,000 t in the Indian Ocean (recent five year averages).

FISHING METHODS

Bigeye tuna is caught predominately by longline and purse seine (both targeted and non-targeted). Other gears also used, but accounting for a significantly smaller proportion of the catch, are pole and line (limited), handline and troll, and gillnet.

Western and Central Pacific

Bigeye tuna of sashimi size and quality is the most valuable of the tropical tunas and is the principal target of large distant-water longliners which freeze catches, and of the smaller, locally-based fresh sashimi vessels (National Oceanic and Atmospheric Administration, 2007). Within the Pacific Ocean, bigeye tuna is distributed through the basin but the bulk of the catch is made towards the eastern and western ends of the ocean basin. Bigeye tuna fisheries in the Western and Central Pacific Ocean (WCPO) are diverse, ranging from small-scale artisanal operations in the coastal waters of Pacific states, Indonesia and Philippines, to industrial purse-seine, pole and line, and longline operations in the exclusive economic zones of Pacific states and in international waters.

The majority of the catch in the WCPO is taken in equatorial areas, by both purse-seine and longline. The longline catch is predominately taken in the central Pacific, contiguous with the important traditional bigeye tuna longline area in the eastern Pacific. Some of the longline catch is within sub-tropical areas, for example, east of Japan and off the east coast of Australia.

The domestic surface fisheries of the Philippines and Indonesia take large numbers of small bigeye in the range 20-50 cm. In addition, large numbers of 25-75 cm bigeye tuna are taken in purse seine fishing on Fish Aggregating Devices (FADs), which along with the fisheries of the Philippines and Indonesia account for the bulk of the catch by number.

Large bigeye tuna are rarely taken in the WCPO purse-seine fishery, and only a relatively small amount comes from the handline fishery in the Philippines. This contrasts with large yellowfin tuna, which, in addition to the longline catch, is also taken in significant amounts from unassociated schools in the purse-seine fishery and in the Philippines and Indonesian handline fishery.

By weight, the longline fishery accounts for most of the bigeye tuna catch. Bigeye tuna sampled in the longline fishery are predominantly adult fish, with a mean size of approximately 130 cm; most fish are between 80 and 160 cm. Bigeye tuna are generally caught in waters of about 10-15°C, at 100–400m depth, although substantial commercial catches are made where the temperature range is 13–27°C and at depths of at least 200-400m. The best fishing is usually a few days before, during and a few days after a full moon, taking advantage of the fact that large bigeye come close to the surface (50 to 100 m) to feed at night in equatorial waters.

The area fished is determined to some extent by access agreements and the cost of those agreements. The Japanese longline distant water fleet predominately catch bigeye tuna, the majority of which is taken in high seas areas (60% in 2015 and close to 60% on average 2011-2015). A large proportion of Japanese longline distant water fleet catch also occurs within Japan, FSM, Marshall Islands, Palau and Solomon Islands EEZs. Effort shifts seasonally tending north of 10oN and towards high seas areas and the Japan EEZ. Other distant water fleets, such as the Taiwanese large-scale tuna longline fleet also catch the majority of its tuna (mostly albacore and bigeye) in the high seas (average catch in 2011-2015 was 74%). Effort has also shifted between the high seas and within EEZs (and also between EPO and WCPO) for the Korean longline fleet reflecting changes in access arrangements.

Bigeye tuna are also caught by handlining, often around anchored FADs, or by longlining in domestic fisheries in some regions, such as Indonesia, Philippines, and operated by large artisanal fishing vessels. Their catches of quality bigeye tuna are exported as quality fresh chilled product.

Eastern Pacific Ocean

Despite little gene flow between populations of bigeye tuna in the Eastern and Western Pacific Ocean (Philippines and Ecuador), bigeye in the Pacific Ocean appear to comprise a single Pacific-wide population (see more in BIOLOGY). The majority of the bigeye tuna catch in the Eastern Pacific Ocean (EPO) was initially taken by longline vessels, however with the expansion of purse-seine fishing on fish-aggregating devices since 1993, the purse-seine fishery has taken an increasing component of the bigeye catch. Subsequently, fishing mortality of juvenile fish has increased alongside the expansion of the purse-seine fishery catching tuna associated with FADs, although the average size taken is relatively larger in the EPO than the WCPO relating to the shallower EPO thermocline.

Effort has shifted towards the EPO for the distant water Japanese longline fleet with the trend for fishing outside of PICs EEZs and a much higher quota in the EPO (32,372 mt cf. 16,860 mt in 2017).

Indian Ocean

In the Indian Ocean (IO), the distant-water longline fishery commenced operation during the early 1950s and reached a peak in the late 1990s–early 2000s. During the mid-2000s, the total annual bigeye tuna catch declined considerably, primarily due to a decline in the longline catch in the western equatorial region in response to the threat of piracy off the Somali coast. This has recovered somewhat over the following years.

Industrial fisheries account for the majority of catches of bigeye tuna including from vessels equipped with deep-freezers (-600C) and fresh longline and purse seine fisheries by Indonesian, Taiwanese, Chinese, Seychelles, and EU-Spanish fleets mainly in the Western Indian Ocean but also in the Eastern Indian Ocean. The fishery by deep-freezing longliners is dominated by Taiwanese fleets accounting for as much as 40-50% of the total longline catch in the IO. Bigeye tuna caught by purse seiners in the IO are dominated by the EU and Seychelles fleets and are mainly small juvenile bigeye tuna (around 5 kg).

The sizes exploited in the IO range from 30 cm to 180 cm fork length. Newly-recruited fish are primarily caught by the purse seine fishery on floating objects where they form mixed schools with skipjack tuna and juvenile yellowfin and are mainly limited to surface tropical waters, while larger fish are found in sub-surface waters.

Bigeye tuna are also caught by handlining, often around anchored FADs, or by longlining in domestic fisheries in some regions, such as Maldives, Sri Lanka and (presumably) other coastal IO States, and operated by large artisanal fishing vessels. Their catches of quality bigeye tuna are exported as quality fresh chilled product.

Gillnet fisheries also take a substantial catch but reporting is minimal.

INDUSTRIAL-SCALE FISHERIES

The industrial scale longline industry is characterised by two main vessel types – large-scale distant water vessels (supplying frozen tuna) and small-medium scale offshore vessels (supplying fresh tuna). Longline vessels targeting albacore or other species may also supply incidental bigeye catch to the fresh sashimi market.

Bigeye tuna caught in the longline fishery (and Japanese pole and line fishery) are placed in ultra-low temperature (ULT) freezers capable of reaching temperatures of -55oC to -60°C for storing catch, and after arriving at port, may be air-freighted to Japanese, European or US markets where they are sold as sashimi or fresh chilled fish or sold and transported to local markets.

SMALL-SCALE FISHERIES

Artisanal fisheries are defined as those undertaken by fishing boats having overall length (LOA) of less than 24 m and operated full-time within the EEZ of their flag States. In most coastal States such vessels engage in fully commercial fishing – notably in the 18 member States of the IOTC, and in Indonesia, the Philippines and Vietnam. Fishing fleets in developing countries are very diverse, some fleets are multipurpose and artisanal or traditional in nature. Unless hand-lining at night, truly subsistence fleets are less likely to catch bigeye tuna in commercial quantities.

The domestic Indonesian and Philippine fisheries employ various gears for catching bigeye (targeted and non-targeted) including ring net, pole and line, handline, longline, and purse seine. These fisheries, such as the Philippine domestic purse seine and ring net fisheries, are FAD-based fisheries and, within Philippine waters, mainly catching juvenile tunas. The domestic fisheries catch juvenile bigeye tuna from 15 to 78 cm in length (average 28 cm). Enhancements have been made to some small scale longline vessels to improve their freezing and fish hold capacity to access high-quality markets and increase autonomy at sea (e.g. Taiwanese longline fleet).

RECREATIONAL FISHING

Bigeye tuna is an excellent sport fish. Recreational fishing methods are: trolling deep with squid, mullet or other small baits, and artificial lure and live bait fishing in deep waters.

AQUACULTURE

Although approval had been given for a yellowfin and bigeye tuna farm off Hawaii, it never began commercial operations before closing down in 2017. The Research Institute for Mariculture in Gondol, Bali conducted research from 2003 to 2010 to analyse to develop techniques for tuna species resource enhancement however has since closed. Cage grow-out of bigeye tuna is not conducted. The life-cycle of bigeye tuna has not been closed.

GUIDE TO FURTHER READING

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

On species importance, see: FAO Species Fact Sheet for bigeye tuna http://www.fao.org/fishery/species/2498/en, and ISSF (2018).

On fishing methods, see for the WCPO, see: National Oceanic and Atmospheric Administration (2007), Brouwer and others (2017), Leroy and others (2013), Hanamoto (1987), Farley and others (2006), Lehodey and others (2011), Boggs (1992), Beverly and others (2003 in McCoy & Gillett, 2005), Campling and others (2017), Babaran (2006), and Harley and others (2009).

For the EPO, see IATTC (2016), and Campling and others (2017).

For the IO, see: IOTC (2016), IOTC (2017), and IOTC (2011).

For industrial-scale fishing, see: Hamilton and others (2011).

For small-scale fishing, see: Miyake and others (2010), USAID (2017), WCPFC (2017), and Campling and others (2017).

For recreational fishing, see: the International Gamefishing Association (www.igfa.org).

General descriptions of the main gear types used for the capture of bigeye tuna can be found at: http://www.fao.org/fishery/fishtech/1010/en.

REFERENCES

  • Babaran, RP. 2006. August. Payao fishing and its impacts to tuna stocks: A preliminary analysis. In Second regular scientific meeting. WCPFC. Manila (pp. 7-8).
  • Boggs, CH. 1992. Depth, capture time, and hooked longevity of longline-caught pelagic fish: timing bites of fish with chips. Fish. Bull., 90, pp.642-658.
  • Brouwer, S, G Pilling, J Hampton, P Williams, S McKechnie & L Tremblay-Boyer. 2017. The Western and Central Pacific tuna fishery: 2016 overview and status of stocks. Noumea, New Caledonia: Pacific Community. https://www.wcpfc.int/node/30158
  • Campling, L, A Lewis, & M McCoy. 2017. The Tuna Longline Industry in the Western and Central Pacific Ocean and its Market Dynamics. Honiara: Pacific Islands Forum Fisheries Agency. http://www.ffa.int/system/files/Campling-Lewis-McCoy%202017%20The%20Tuna%20%20Longline%20Industry.pdf
  • FAO (Food and Agriculture Organisation of the United Nations) Fisheries and Aquaculture Department. 2017. Species fact sheets: Thunnus obesus. http://www.fao.org/fishery/species/2498/en
  • Farley, JH, NP Clear, B Leroy, TL Davis, & G McPherson. 2006. Age, growth and preliminary estimates of maturity of bigeye tuna, Thunnus obesus, in the Australian region. Marine and freshwater Research, 57(7), pp.713-724.
  • Hamilton, A., A Lewis, M.A. McCoy, E Havice, & L Campling. 2011. Market and industry dynamics in the global tuna supply chain. Honiara, Solomon Islands: Pacific Islands Forum Fisheries Agency. https://www.ffa.int/system/files/Global%20Tuna%20Market%20%26%20Industry%20Dynamics_Part%201a.pdf
  • Hanamoto, E. 1987. Effect of oceanographic environment on bigeye tuna distribution. Bull. Japan. Soc. Fish. Oceanogr, 51:213-216.
  • Harley S, S Hoyle, A Langley, J Hampton & P Kleiber. 2009. Stock assessment of bigeye tuna in the Western and Central Pacific Ocean. Western and Central Pacific Fisheries Commission Scientific Committee Fifth Regular Session, 10-21 August 2009, Port Vila, Vanuatu. WCPFC-SC5-2009/SA-WP-4. 98 p.
  • IATTC (Inter-American Tropical Tuna Commission). 2016. Tunas, billfishes and other pelagic species in the Eastern Pacific Ocean in 2015. La Jolla, California: Inter-American Tropical Tuna Commission.https://www.wcpfc.int/system/files/GN-WP-02%20IATTC%20Tunas-billfishes-and-other-pelagic-species-in-the-EPO-2015.pdf
  • IOTC (Indian Ocean Tuna Commission). 2011. Executive Summary: status of the Indian Ocean bigeye tuna (Thunnus obesus) resource. IOTC-2011-SC14-09. 9 p.
  • IOTC (Indian Ocean Tuna Commission). (2017). Status summary for species of tuna and tuna-like species under the IOTC mandate, as well as other species impacted by IOTC fisheries. Victoria Mahé, Seychelles: Indian Ocean Tuna Commission. http://www.iotc.org/science/status-summary-species-tuna-and-tuna-species-under-iotc-mandate-well-other-species-impacted-iotc
  • IOTC (Indian Ocean Tuna Commission). (2016). Stock assessment of bigeye tuna in the Indian Ocean for 2016 — model development and evaluation IOTC-2016-WPTT18-20. Victoria Mahé, Seychelles: Indian Ocean Tuna Commission. http://www.iotc.org/documents/stock-assessment-bigeye-tuna-indian-ocean-2016
  • ISSF (International Seafood Sustainability Foundation). 2018. Status of the world fisheries for tuna. February 2018. ISSF Technical Report 2018-02. International Seafood Sustainability Foundation, Washington, D.C., USA.
  • Leroy, B, J Scutt Phillips, S Nicol, GM Pilling, S Harley, D Bromhead, S Hoyle, S Caillot, V Allain, & J Hampton. 2013. A critique of the ecosystem impacts of drifting and anchored FADs use by purse- seine tuna fisheries in the western and central Pacific Ocean. Aquat. Living Resour. 26, 49–61.
  • Lehodey P, J Hampton, RW Brill, S Nicol, I Senina, B Calmettes, HO Portner, L Bopp, T Ilyina, JD Bell & J Siebert. (2011). Vulnerability of oceanic fisheries in the tropical Pacific to climate change. In: Bell JD, Johnson JE, Hobday AJ (eds) Vulnerability of Tropical Pacific Fisheries and Aquaculture to Climate Change. Secretariat of the Pacific Community, Noumea, New Caledonia, pp. 433–492.
  • McCoy, MA & RD Gillett. 2005. Tuna Longlining by China in the Pacific Islands: a description and considerations for increasing benefits to FFA member countries. Pacific Islands Forum Fisheries Agency.
  • 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.
  • National Oceanic and Atmospheric Administration. 2007. Fishery Management Plan for U.S. West Coast Fisheries for Highly Migratory Species. As amended. Appendix A: Description of the fishery. Portland, Oregon: National Oceanic and Atmospheric Administration. http://www.pcouncil.org/wp-content/uploads/2017/03/HMS_AppA_pt1.pdf
  • USAID (United States Agency for International Development). (2017). Value Chain Assessment: General Santos City, Philippines. Manila, Philippines: United States Agency for International Development/Regional Development Mission for Asia. 
  • WCPFC (Western and Central Pacific Fisheries Commission). 2017. Western and Central Pacific Fisheries Commission Tuna Fishery Yearbook 2016. Noumea, New Caledonia: Oceanic Fisheries Programme Pacific Community. https://www.wcpfc.int/statistical-bulletins

Links