Figure 1.15 Bluefin Tuna Do Not Recognize Boundaries (A) Marine biologist Barbara Block attaches computerized data-recording tracking tags to a live bluefin tuna before returning it to the Atlantic Ocean, where its travels will be monitored. (B) Tracking data from eastern (Mediterranean) and western (Gulf of Mexico) breeding populations of bluefin tuna. At one time commercial fishing regulatory agencies assumed that bluefins from western- and eastern-breeding populations fed on their respective sides of the Atlantic. To speed recovery of the endangered western population, fishing quotas were created for each side of the mid-Atlantic Ocean (dashed line).