Ultra-low temp
    From transportation to sales, the processed tuna and tuna-like species are frozen to maintain its freshness. Ultra-low temperature freezing method and refrigerated sea water freezing method are the two major freezing methods that are used to maintain caught tunas’ freshness.

    Ultra-low temperature freezers are capable of maintaining the storage room temperatures at minus 55 degrees Celsius or lower, which can extend the shelf life, the freshness can be maintained for a period of 2 to 3 years. Comparing with the fishes that used refrigerated sea water freezing method, since the caught fishes are stored at minus 20 to 30 degrees Celsius, the freshness can only be maintained for 25 days.

    In addition, the vessels that carry ultra-low temperature freezer need to be over 24 meters length, which the initial capital investment will be much higher than the vessel that is using refrigerated sea water freezing method, its length is less than 24 meters. As a result, the ultra-low temperature freezing method is usually used for storage of bigeye and yellowfin tuna which have relatively higher market value. The refrigerated sea water freezing method is used for storage of skipjack and albacore, which have relatively lower market value.