The Pacific Bluefin Tuna (PBT) has been designated as a vulnerable level of endangerment since 2014. The biggest reason for the decreasing population of PBT is overfishing. PBT is a popular type of tuna in many countries; for example, Japan is the country that fishes PBT the most, accounting for more than a half of the total global catch. Excessive PBT fishing in the country has led in catching juvenile PBT that have not spawned yet due to shortage of adult PBT and easiness of catch. As a result, PBT population has decreased, especially the population of those that can reproduce.