Abstract
Fish of the tribe Thunnini represent a significant proportion of the stock caught by the fishing industry, with many of these fishes being collectively called tuna. However, only certain species can be used legally as an ingredient in canned tuna products, depending on regional food regulations. In Taiwan, only Thunnus species or Katsuwonus pelamis can be used as canned tuna. Here, we authenticated 90 canned tuna products, including 25 cat food samples, by sequencing two mitochondrial regions, 16S rRNA (16S) and the control region (CR). BLAST analysis revealed that Sarda orientalis, Euthynnus affinis, Auxis rochei, and Auxis thazard are all used as substitutes for legitimate tuna products. We found that 63.33% of investigated samples are true canned tuna, i.e., contain Thunnus species or skipjack tuna. We advocate that the Taiwanese government publishes an official standardized list of fishes, especially so that scientific, Chinese and vernacular names can be assigned unambiguously based on a “one species-one name policy”, thereby clarifying which species can be used in seafood products such as tuna. Furthermore, we feel that the large-scale and long-term monitoring of canned tuna products is warranted to fully assess the extent of tuna product adulteration in Taiwan.
Highlights
17% of the global human population’s intake of animal protein in 2017 constituted fish [1]
We observed inconsistent labeling in 11 of 65 canned tuna products destined for human consumption, but no such problem with cat food products
Inconsistent labeling reflected canned tuna products claiming to be made from oriental bonito (Sarda orien26 of 33 talis) or displaying the ambiguous vernacular name 煙仔虎, which can refer to either skipjack tuna or oriental bonito (Figure 1, Table 2)
Summary
17% of the global human population’s intake of animal protein in 2017 constituted fish [1]. Aquaculture satisfied about half of that consumption, wild-capture from oceans, lakes and rivers remains a mainstay of the global fishing industry. Among these wild-caught fishes, scombrids are important fishery resources, especially species in the tribe Thunnini that constitute ~10% of the international seafood market [2,3]. The tribe Thunnini comprises five genera: Thunnus (in Chinese: 鮪屬), Katsuwonus (in Chinese: 正鰹屬), Auxis (in Chinese: 花鰹屬), Euthynnus (in Chinese: 巴鰹屬), and Allothunnus (in Chinese: 細鰹屬). Fishes of this tribe can be generally termed “tuna”. Auxis rochei is called bullet tuna (in Chinese: 圓花鰹), Euthynnus alleteratus is little tunny (in Chinese: 小巴鰹), and Allothunnus fallai is slender tuna (in Chinese: 細鰹)
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