How do we know where a mako goes? Plastic dart tags show where a mako was tagged and where it was caught again, but not when it moved, how long it took or the route it followed. Other tags send their data by satellite, and some send a signal each time the shark surfaces. In New Zealand, 14 tagged makos had satellite tags fixed to their dorsal fins, which send a signal whenever the fin breaks the sea surface. Tagged makos there travelled between 2,000 and 20,000 kilometres in total, an average of 10,000 kilometres, and the farthest any went from where it was tagged was between 311 and 2,904 kilometres. Twelve of the 14 went farther than 1,000 kilometres.

Those numbers sound like the record of a wanderer, but the tags told a second story. Tagged makos switched between a Resident state, mostly in coastal waters, and a Travel state, mostly in the open ocean. They spent a median of 77 percent of their time in New Zealand waters, which challenged the view that makos are nomadic wanderers.

Depth and temperature add more detail. Makos in a New Zealand study made frequent dives between the surface and 300 to 400 metres, reaching 515 and 605 metres, but spent most of their time shallower than 100 metres, and they met water temperatures from about 9 to 28 degrees Celsius. In the Atlantic, makos were seen in water ranging from 5.2 to 31.7 degrees Celsius, but mainly at 22 to 27 degrees. Makos spend most of their time in the mixed layer of the ocean, with few trips below the thermocline.

Long journeys do happen, and they cross borders. In the western Gulf of Mexico, makos were tracked for 10 to 887 days, and two mature males made seasonal migrations of about 2,500 kilometres. Managing makos is hard because they cross many borders: those two males passed through at least 12 jurisdictional boundaries.

Makos also come back. Tags on a roughly seven-foot female mako showed she followed similar courses into the Pacific and back to the California coast over three years in a row, and makos tagged off California came back to the same offshore areas year after year. Some females seem to return to the same birthing and nursery sites, such as the Southern California Bight, the Strait of Gibraltar and the area off Brazil between 17 and 35 degrees south. Mako sharks are non-territorial, and little is known about the size of their home ranges, so the question of wanderer or neighbour is still being answered.

Words to know

• thermocline: cooling layer
• nomadic: always moving
• Resident: staying put
• jurisdictional: legal area