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

Yellowfin tuna is a highly migratory fish species. It lives in tropical and subtropical oceanic waters, above and below the thermocline. It is found throughout the Indian Ocean (IO) and Western and Central Pacific Ocean (WCPO) except in areas where ocean depth is less than about 50m. Yellowfin tuna also lives in the Atlantic Ocean.

Smaller yellowfin tuna are mainly limited to surface waters, while larger fish are found in both surface and deeper waters, but rarely below 250m.

FISHERIES

02-2009-05010 PK Manado YFT DSCN0163-smGlobally, yellowfin tuna comprise about a quarter of the total tuna catch (all species), and Asia-Pacific yellowfin tuna are more than 70% of the global yellowfin tuna catch. Of the four main tuna species caught (albacore, bigeye, skipjack, and yellowfin), yellowfin tuna comprises 24% of the total tuna catch of the WCPO and about 42% of the IO tuna catch. The main production areas are in the north and west of Madagascar (IO) and the western equatorial belt (WCPO).

Using many different fishing gears, yellowfin tuna are caught by local fishers (including artisanal and traditional coastal fishery fleets) and foreign licensed vessels. The artisanal fleets of Indonesia and the Philippines often operate around anchored FADs. Juveniles are caught by purse seine, pole and line, handline, trolling, and - especially in the Indian Ocean - gillnets. Adult yellowfin tuna are caught mainly by pelagic longline and handline. Yellowfin tuna are also a popular recreational species with game-fishing (angling) clubs and with tourists in many Asian-Pacific countries, e.g. Indonesia, Malaysia, Philippines and Australia.

SUSTAINABILITY AND MANAGEMENT

Yellowfin tuna is a fast-growing and highly productive species. Although heavily fished, the yellowfin tuna stock of the Western and Central Pacific Ocean is not overfished. In the Indian Ocean, however, the yellowfin tuna stock is considered as overfished and subject to overfishing, due to an increase in catch levels in recent years. In both oceans, scientific assessments indicate concern for the levels of fishing mortality, increasing surface fisheries on juveniles, and on the environmental effects of fishing by certain of the main fishing gears, especially purse seining on floating objects including fish aggregating devices (FADs), longlining and gillnetting.

Yellowfin resources are managed by the Indian Ocean Tuna Commission (IOTC), the Western and Central Pacific Fisheries Commission (WCPFC), the Pacific Islands Forum Fisheries Agency (FFA) and national governments. International environmental organisations and market controls also have a strong influence on the governance of yellowfin tuna fisheries.

VALUE CHAINS

Yellowfin tuna is marketed mainly frozen (whole fish, loins) and canned, but also fresh (chilled whole fish, loins, fillets) and smoked. Juvenile yellowfin tuna caught in the purse seine fishery are canned. Very small juveniles are sold in local markets in the Philippines and Indonesia as plate-sized small pelagic fish. Throughout its range, yellowfin tuna is consumed by local urban and rural communities. It is served raw (as prime sashimi and sushi), grilled, barbecued, deep or lightly-fried, and smoked.

The yellowfin tuna fishery provides tens of thousands of jobs in fishing and processing – including for women – although many fishing crew and processing workers are low-paid and their work is arduous. Men comprise the crews and officers of fishing and fish cargo vessels. The majority of cannery production workers are women, although men are engaged in heavy factory tasks. Women may join men in positions such as processing factory production managers; they are also the main sellers at domestic markets. Women are also beginning to enter non-traditional areas of work in the tuna fishing industry, e.g. as observers on purse seine vessels and as staff on tuna tagging research programmes.

Key benefits of the local and oceanic tuna fisheries are economic development, government revenue, significant contributions to food security and employment. Governments of small island developing states in the Pacific and Indian Oceans receive substantial revenue from granting fishing licences to foreign vessels. For countries with onshore processing facilities, greater benefits are received by those with direct air links to the USA and Japan and those that offer suitable port facilities.

FOOD

As food, yellowfin tuna is a very good source of low-fat protein and is low in sodium but has a moderate level of cholesterol. It is a very good source of thiamin, selenium, vitamin B6, and omega-3s. While frequent consumption of fish with high concentrations of mercury by pregnant and lactating women can affect neuro-development in children, yellowfin tuna caught from the Pacific Ocean have relatively low levels of mercury, and high levels of selenium which gives a protective effect against mercury toxicity.

ECOSYSTEMS AND CLIMATE

The capture of bycatch, including juveniles of bigeye tuna and also of sea turtles, sharks and other marine fish species, during tuna fishing operations is a significant environmental issue. Also, unless strictly managed, regional fish canneries may have negative effects on surrounding land and sea environments and the resources they support.

Global warming affects the distribution and catchability of yellowfin tuna stocks which are sensitive to changes in oceanic circulation, the stratification of the water column and water temperature and density. The effects of ocean acidification on yellowfin tuna have yet to be assessed, although preliminary research has commenced by the Inter-American Tropical Tuna Commission (IATTC) and the Oceanic Fisheries Programme (OFP) at the SPC.

The area of suitable yellowfin tuna habitat changes with seasons and with inter-annual climate variability. For example, the deepening of the thermocline in the eastern Pacific and shoaling of the thermocline in the west during El Niño events changes the catchability of yellowfin tuna.

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