Eastern Little Tuna
Known locally as the bonito or kawakawa, the eastern little tuna is a silver-coloured game fish with distinct mackerel patterning along its dorsal ridge. It is found in the Indian and West Pacific oceans, and is considered abundant throughout its range. The bonito favours
warm water, and although it is classified as a pelagic fish, it remains close to shore at depths of up to 50 metres. It is highly migratory, often forming large schools of up to 5,000 individuals alongside other small tuna species. The bonito reaches a maximum length of one metre, and is an opportunistic predator. It feeds on small fish, plankton, squid and crustaceans, and is listed as Least Concern on the IUCN Red List despite being frequently caught as by-catch by commercial fisheries.
Skipjack tuna have many different names, including arctic bonito, striped tuna and victor fish. They are found in tropical waters all over the world, and frequently form shoals of up to 50,000 fish. They stay predominantly at the surface, and grow up to one
metre in length. Skipjack tuna are identified by their bold horizontal stripes. They lack scales everywhere on their body except for their lateral line (which they use to detect movement in the water), and their corselet (a thick band directly behind the head). They are the smallest commercially fished tuna, and in 2009 global catch reports showed that 2.6 million tons of skipjack were landed in a single year. They reproduce quickly and are considered sustainable; however, they are often contaminated with mercury.
Yellowfin tuna are a pelagic species found in tropical and subtropical oceans worldwide. They spend most of their lives offshore, but occasionally come inshore of the continental shelf to feed. Although they usually stay within 100 metres of the surface, tagged individuals have been recorded at
depths of over 1,000 metres. Yellowfin tuna are characterised by their large size (often exceeding 180 kilograms), their metallic blue colouring and their sickle-shaped yellow fins. The only tuna larger than the yellowfin are the bigeye, and all three species of bluefin tuna. They are exceptionally fast predators thanks to their streamlined shape and the fact that unlike most fish species, they are warm-blooded. They prey mostly on other fish and are at risk of overfishing.
Striped bonito are also known as mackerel or oriental bonito and are widespread throughout the Indian and Pacific oceans. They are abundant in some areas and rarely found in others, leading scientists to believe that there may be several distinct populations within
their range. Striped bonito are classified as coastal pelagic, meaning that they prefer inshore open ocean; where they often school with other small tuna species. They are silvery-grey in colour, and identified by a series of diagonal black stripes on the upper half of their body. Striped bonito are carnivorous, preying mainly on small fish, squid and crustaceans. They are not fished commercially and are therefore listed as Least Concern on the IUCN Red List – however, they are targeted by artisanal fishermen.
King mackerel – Scomberomorus commerson
Queen mackerel – Scomberomorus plurilineatus
Chub mackerel – Scomber japonicus