Unfortunately, bluefin tuna are reproductive late bloomers & aren't mature to reproduce until almost 8 years old. The increased demand for bluefin & their late reproduction has led to something near a 90% decrease in the bluefin population. As foodies we must eat responsibly & demand global policies for responsible farming/harvesting/fishing/ranching/hunting. If we don't, the food and world we love won't exist for future generations to enjoy.
Please read the article, A sushi master's lament