 This, together with the organization of blood vessels and a countercurrent heat exchange system, allows the southern bluefin tuna to rapidly deliver oxygen to tissue, while preserving energy necessary for their active lifestyle.Southern bluefin tuna migrate between a variety of different ocean regions, however the osmotic conditions faced by the tuna stay relatively similar.This species of tuna inhabits ocean areas that are relatively high in salinity compared to the rest of the world's oceans.