Bluefin Tuna

Bluefin tuna is one of the largest tuna species. It is distributed throughout the Atlantic and Pacific oceans in subtropical and temperate waters, as well as in the Indian Ocean.  The popularity of bluefin tuna is reflected in highly lucrative global tuna markets.

Estimated to be worth approximately $10 million annually,  Canada’s Western Atlantic bluefin tuna fishery attracts more than 750 licensed harvesters who fish the western Atlantic bluefin tuna stock in Canadian waters over the Scotian Shelf, in the Gulf of St. Lawrence, in the Bay of Fundy, and off the coast of Newfoundland and Labrador. The fishing season is related to the highly migratory pattern of tuna and generally takes place between July and November, when tuna migrate into Canadian waters.

Because bluefin tuna migrate over long distances, and fisheries for this species often occur on the high seas, international co-operation is necessary to ensure its conservation:

• Atlantic bluefin tuna is managed by the 48-member International Commission for the Conservation of Atlantic Tunas (ICCAT)
  
  
• Bluefin tuna in the north Pacific is co-operatively managed by two regional fisheries management organizations: the 16-member Inter-American Tropical Tuna Commission (IATTC) and the 26-member Western and Central Pacific Fisheries Commission (WCPFC).
  
  
• Southern bluefin tuna, which frequents both the Pacific and Indian Oceans, is managed by the five-member Commission for the Conservation of Southern Bluefin Tuna (CCSBT)

The popularity of bluefin tuna in highly lucrative markets has led to extensive exploitation in several areas. Canada has been a strong advocate for conservation using the precautionary approach to stock management. In recent years, Canada has played a leading role in efforts at ICCAT to address overexploitation through science-based management and to ensure compliance and combat illegal, unreported and unregulated fishing activities. These efforts with our international partners have resulted in some  important advancements in bluefin tuna management and Canada will continue to press the ICCAT Members to follow through on these commitments.

Information below on the status of bluefin stocks is based on the 2012 update assessment of ICCAT’s Standing Committee on Research and Statistics and the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific Ocean. Refer to: http://www.iccat.int/Documents/SCRS/ExecSum/BFT_EN.pdf (PDF 901,1 KB) and http://isc.ac.affrc.go.jp for more details.

Eastern Atlantic and Mediterranean Bluefin Tuna

The Eastern Atlantic and Mediterranean bluefin tuna continues to be considered one of the most overfished fish stocks, however, significant efforts have been made in recent years at ICCAT to improve management and enforce these rules on the high seas and in domestic waters. As a result, there is some encouraging signs for the future of Eastern Atlantic and Mediterranean bluefin tuna.

The 2010 ICCAT stock assessment, which was updated in 2012, indicates spawning stock biomass is showing moderate growth. However, scientists involved in this assessment have stressed that there remains a high level of uncertainty in this assessment of the stock as a result of significant data limitations due to chronic underreporting and illegal, unreported, and unregulated (IUU) fishing in the past.

The 2012 quota set by ICCAT for Eastern Atlantic and Mediterranean bluefin tuna was 12,900t to achieve stock objectives outlined in the Eastern Atlantic bluefin tuna recovery plan.The quota for this stock has been decreased by more than half since 2009.

Western Atlantic Bluefin Tuna

The Western Atlantic bluefin tuna is the stock fished in Canada. The 2010 ICCAT stock assessment, which was updated in 2012, indicates that the spawning stock biomass for the Western Atlantic bluefin tuna continues to increase moderately, with the highest increases being seen in the Gulf of St. Lawrence.

At the 2010 annual meeting of ICCAT, members adopted a lowered overall quota of 1,750t for 2011 and 2012 to achieve stock objectives outlined in the western Atlantic bluefin tuna recovery plan. Canada’s share of this total catch for 2012 was 396.7t from ICCAT plus an 86.5t transfer of quota from Mexico.

Satellite tagging conducted by Canadian and American scientists, as well as recent origin of birth studies, have revealed that the bluefin tuna fished by Canadian harvesters were born in the Gulf of Mexico, whereas the birth origin of bluefin harvested in U.S. waters included both the Gulf of Mexico and the Mediterranean Sea. While research in this area continues, the results of these studies provide evidence of the ‘mixing’ of Western and Eastern Atlantic stocks. This is important because the severe overfishing that has been taking place in the Eastern Atlantic and Mediterranean Sea might have seriously impeded the health of Western Atlantic bluefin tuna. Age-growth studies conducted by Canadian and American scientists may also improve future assessments of Western Atlantic bluefin tuna because new growth data will be used to better reflect the characteristics of the Western Atlantic bluefin tuna stock within the bluefin tuna growth model.

Northern Pacific Bluefin Tuna (Eastern and Western Pacific)

There is one single stock of Pacific bluefin tuna that spawn in waters between the Philippines and Japan before migrating more than 11,100 kilometres to the Eastern Pacific, only to return to their birth waters to spawn again.

The total catch of Pacific bluefin tuna has fluctuated widely from 1952 to 2004: from 9,000t to 40,000t. Recent catch levels average approximately 22,000t. Canada does not have a directed Pacific bluefin tuna fishery nor is Pacific bluefin tuna caught incidentally by its albacore tuna fishery.

The most recent stock assessment of Pacific bluefin tuna was conducted in 2008 by the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific. It noted that the spawning biomass is currently at historically median levels at 20,000 t. The Committee also assessed the impact of environmental changes on these tuna and advised that current levels of fishing could continue if environmental conditions remained the same, but they also noted that if fishing effect was reduced, it could, over time, lead to higher yields.

The Inter-American Tropical Tuna Commission set its total allowable catch of bluefin tuna (PDF 17,4KB) by all its member countries at 10,000t for 2012-2013. The Western and Central Pacific Fisheries Commission has limited its total fishing effort (PDF 17,4KB) to below the 2002-2004 levels for 2013 (a renewal of the management measures in place for 2011-2012).

Southern Pacific Bluefin Tuna

Southern bluefin tuna are found throughout the Southern Hemisphere mainly in waters between 30 and 50 degrees south. The only known breeding area is in the Indian Ocean, south-east of Java, which takes place from September to April. From December to April, bluefin tuna tend to congregate near the surface of the coastal waters off the southern coast of Australia, and spend the winter months in deeper, temperate oceanic waters. After age five, Southern Pacific bluefin tuna are seldom found in near shore surface waters.

According to the CCSBT’s Scientific Committee report in 2008, overall recruitment levels of Southern Pacific bluefin tuna remain lower than the 1990s and considerably lower than the 1980s. Major quota holders in 2008 were Australia at 5,265t and Japan at 3,000t.