Bluefin tuna aquaculture is difficult. For one thing, bluefin have a hard time producing eggs in captivity due to stress. Therefore, until recently, this species has more successfully been ranched rather than farmed, by holding wild-caught fish in cages to fatten them up before harvest. Moreover, the idea of farming them in land-based facilities seemed far-fetched at best. But things have suddenly changed. In the first-time-ever category of achievements, researchers from the Spanish Institute of Oceanography in the Region of Murcia have managed to reproduce the bluefin tuna (Thunnus thynnus) in an onshore facility.
The institute has a facility, based in Cartagena, which the Ministry of Science and Innovation has declared a Singular Scientific and Technical Infrastructure for Bluefin Tuna Farming, that is used for controlled bluefin reproduction. It contains two big tanks (20 and 22 meters in diameter and 10 meters deep), and two smaller ones (14 and 8 meters diameter) with combined seawater capacity of 7 million liters. Two groups of bluefin tuna populate the tanks, one containing 25 fish born in 2017 and the other eight fish born in 2018.
In July of this year scientists injected hormones into the second group of tuna to induce final maturation and egg laying, thereby overcoming the stress-caused difficulty noted earlier. Three days later the tuna produced 3 million eggs. While the Institute had done this with tuna in sea-based floating cages, this had never been done in a land-based facility. The next step is to see how the newborns survive and, in the future, perhaps reproduce themselves.