Tuna is one of the top fish commodities in the international seafood trade. Within its family, the bluefin tuna can attain astonishing high market prices which has led to a dramatic decline in many wild stocks. This has triggered the development of bluefin tuna aquaculture (BFT) as an economic alternative for meeting the growing demand.
According to the UN Food and Agriculture Organisation (FAO) bluefin tuna (BFT) aquaculture constituted 18 percent of global BFT production in 2011.
However, in a new study published in the journal Reviews in Fisheries Science & Aquaculture, this estimate is far below the actual production.
The study, which is written by centre researchers Marc Metian and Max Troell together with colleagues from Duke University, provides an overview of the global bluefin aquaculture industry and specifically points out some mismatches of production statistics.
"Capture fisheries data from FAO are the main source of comprehensive global fishery statistics, but the bluefin tuna statistics that FAO receives from the Regional Fisheries Management Organisations seem unreliable for farmed BFT," says Marc Metian.
Previous research has showed that volumes calculated from tuna trade do not match with official numbers reported by countries. For instance, data from 2009 on BFT aquaculture production shows how FAO reported approximately 12,000 tonnes and national sources more than 30,000 tonnes.
"The fact that tuna aquaculture involves both a fishing phase and a farming phase is probably causing confusion"
Marc Metian, co-author
Marc Metian says that the under-reporting and underestimation of BFT farming is worrying, particularly the numbers coming from Japan, The Mediterranean Sea and Australia.
The Mediterranean Sea, for instance, involves a large number of countries and actors that are actively involved in BFT capture fisheries and farming operations. However only a third of the total production was presented in FAO statistics from 2007. National statistics were also not available or detailed enough for all Mediterranean countries, only Portuguese statistics were totally in line with FAO’s statistics.
Time to harmonise
"In order to improve the management of BFT, leading countries need to revise their statistics and solve problems with misreporting, underreporting and illegal catches," co-author Max Troell says.
He stresses that this should be a collective effort between the producing countries and international organisations such as FAO. A harmonisation of data will help the scientific stock assessment and facilitate more sustainable quotas. This would have to involve better estimation of fish sizes and weight caught for aquaculture.
"Maybe more than a need for simple innovations in terms of technology used to accurately quantify fish, there is also need for increased transparency in on-farm management and on-board fishing boats," Troell says.
Either way, concludes co-author Marc Metian, if appropriate systems are in place, production through aquaculture could potentially improve the overall record of total allowed bluefin tuna catches as farming activities should be easier to monitor compared to wild capture.
"However, as we identified in the study, there still remains some major sustainability challenges for tuna farming considering it dependency on wild fish stocks both for seed and feed," Metian says.
Metian M, Pouil S, Boustany AM, and M Troell. 2014. Farming of Bluefin tuna – reconsidering global estimates and sustainability concerns. Reviews in Fisheries Science & Aquaculture 22 (3): 184-192.
Max Troell is a system ecologist mainly working with environmental problems associated with aquaculture.
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