The Tuna Family

Abstract

People eating canned tuna probably don’t realise that strictly speaking they are not eating tuna at all. Most canned tuna is skipjack tuna after all, and skipjack is a member of the Scombridae family, to which next to the real tuna’s as Atlantic Bluefin tuna (Thunnus thynnus) the mackerel and Atlantic bonito (Sarda sarda) also belong [23]. So skipjack is the tuna family’s bastard cousin; the upstart who, because of its economic significance to the industrial fisheries, was welcomed warmly into tuna aristocracy. Besides being the most important ingredient for canned tuna, skipjack is also used in Japan for the smoked, dried and shaved katsuobushi, a key ingredient for fish soup and many other typically Japanese dishes [127]. The Americans know it, once canned, as ‘light-meat’ tuna [81]. Skipjack, that is found in tropical and subtropical waters, does not grow very big, to around 1.2 kg and 40 cm length at maturity or exceptionally 1 m in length. Horizontal stripes on its belly make it easily recognisable. Like the rest of its family, skipjack is a cosmopolitan migratory fish that moves around in shoals of thousands of fellow fish to hunt for food jointly. This makes it ideal for large-scale purse seine capture as well as for pole and line. In both cases floating rafts or FADs can be used, leading to large amounts of unsustainable bycatch. Skipjack, which can live up to a reported maximum of 12 years, had hitherto been considered a robust stock because of the speed with which they procreated. The fish is sexually mature within a year. They are sometimes called the cockroaches of the sea, although this comparison is seldom made in professional circles, presumably because of the negative connotations as far as hygiene and palatability are concerned (Fig. 29.1).