[ Working the Bluefin
By Roberto Farina ].
Karlin is 47 years old and spends most of his life at sea and knows a lot about Southern Bluefin Tuna (SBT). He told us that the tuna we saw there were caught on longline, ten miles from the coast of Sendang Biru, Malang, East Jawa from April to November each year.
Sendang Biru, is part of Pondokdadap Port, the fifth most important port in Indonesia. “They transport them here quickly for an initial refrigeration process before shipping to their destinations”, he shouted while waving large knife to remove the tail fins. The noise of the old ice machine is hellish. These SBT have to be refrigerated at -60°C before shipping them to the Japanese markets.
Southern bluefin tuna is found in the open waters of the oceans in the Southern Hemisphere mainly between 30°S and 50°S (up to almost 60°S). During spawning, adult fish migrate to tropical seas, from the west coast of Australia water to Indonesian water from September to April each year.
Southern bluefin tuna, like other pelagic tuna species, has several advantages over other marine life forms. It is a warm-blooded fish and can regulate its body temperature up to 10°C above the water temperature. This advantage allows it to maintain high metabolic production for predation at depth and migration over great distances. This leads us to understand that SBT does not limit migration to the temperature of the water. They also migrate between tropical waters along the coasts of Australia, Indonesia ( specifically in the southeastern islands of Java) and India. SBT has a maximum length of 2.5 meters and weight up to 260 kilograms and makes it among the largest bony fish. It can withstand the water temperature from 3°C to 30°C at shallow depths especially during the spawning time.
Southern bluefin tuna is a gourmet food, much in demand for sashimi and sushi and therefore targeted by the fishing fleets of different nations. Several thousand tonnes are caught each year making it an over-exploited species. 90% of the SBT caught in Indonesia is exported and consumed in Japan. It is a tradition in Japan that the foods avaliable at the begining of the year are considered as lucky charms. On January 5, 2019 a 280 kg Pacific bluefin tuna caught off the coast of Omanachi, in northern Japan was sold at the Tsukiji fish market in Tokyo for USD 3.1 million and that made it for USD 5000 per pound. This also means that the strong demand for bluefin tuna is putting tremendous pressure on the species.
SBT is classified as a threatened species and included in the red list by the International Union for Conservation of Nature (IUCN). Its stock status remains ‘overfished’ and it is an urgent obligation to reduce fishing SBT. In 1994, an intergovernmental organization called the Commission for the Conservation of Southern Bluefin Tuna (CCSBT) was created to assign each nation for a responsible management and quotas of the catch. The members of the CCSBT include Australia, the European Union, Taiwan, Indonesia, Japan, the Republic of Korea, New Zealand and South Africa have been doing their utmost promising initiatives. The twenty-fifth meeting of the scientific committee found in 2020 an improvement of stock assessment of 5% annually from the lowest point in 2009. The goal is to rebuild and achieve a 30% biomass level of the spawning stocks by 2035.
To conclude, it is important to highlight a recent WWF report which shows the impressive decline of the species that populate the seas and lands of the entire planet. Populations of vertebrates, mammals, reptiles, birds and fish have plummeted by an average of 69% since 1970. This should lead us to ask “what are we doing to this Planet”? Analyzing how much we consume emerges that in order to live within the capacity of our planet, the ecological human footprint should be lower than the biocapacity of the Earth. It is clear that some areas of the planet resources are over-exploited.
Andrew Terry, the Director of Conservation and Policy at the Zoological Society of London, reminds how “Half of the global economy and billions of people depend directly on Nature. Preventing further loss of biodiversity and restoring vital ecosystems must be at the top of the global agendas to address the growing climate, environmental and public health crises.” How long Karlin will be able to remain in his work if all these overfishing issues are unresolved?