A Deep Blue Sea Icon: Atlantic Bluefin Tuna
Written by Laura Eamon
Depending on who you talk to, the Atlantic bluefin tuna (Thunnus thynnus) can grow up to 13 feet, 2000 pounds, and 40 years of age. Bluefins are the biggest and fastest of all tuna species. That’s not the only thing that makes them special. Atlantic bluefin tuna are also one of the only warm-blooded fish and the most migratory of all fish!
True snowbirds, the bluefins spend summers here in Atlantic Canada and have been known to spend their winters in the Gulf of Mexico, migrating north to south. However, bluefins have also been known to move west to east into the Mediterranean Sea. Some say these tuna can travel around 10,000 kilometres in just one year. That’s almost Nova Scotia to British Columbia and back! Tuna can’t actually breathe unless they’re swimming, so it makes sense they go so far. To help with their swimming, their bodies are built for speed and endurance. Atlantic bluefin tuna can retract their dorsal and pectoral fins into little slots, and their eyes are set flush to their bodies. All of this means these big fish can move really fast, shooting themselves through the water at up to 70km per hour. Known for their speed, the word tuna is derived from a Greek word meaning “to rush”.
From the moment they hatch, Atlantic bluefins are on the hunt for a feast. Juveniles feed on smaller fish, crustaceans, squid, and eels, while adults feed mainly on bait fish such as herring and mackerel. Though they’re big, strong, and fast, these tuna can end up as prey for sharks, marine mammals, and other large fish. Their scale colourings help camouflage them from above and below with metallic blue on top and shimmering silver-white on bottom.
Atlantic bluefin tuna are a top predator in the ocean environment, so they are very important in maintaining balance in their ecosystem. Overfishing and illegal fishing have been the main cause of endangerment for the species, but things are starting to look up! Public awareness campaigns by NGOs and the rise of the sustainable seafood movement have incentivized businesses to engage in better fishing practices. Most recently, the international agreement on catch quotas is now purely based on ecological science and research.
We are so lucky to have these incredible creatures visiting the waters so close to us here in Mi’kma’ki.
We are also thankful for the accessible information from organizations National Geographic, World Wildlife Federation, NOAA, Nature Conservancy of Canada, DFO Canada, and Ocean Conservancy.
Laura is an economics undergraduate student at Saint Mary's University. She participated in the Canadian Conservation Corps in 2021 and worked at the Souris and Area Branch of PEI Wildlife Federation enhancing rivers, playing with dogs, water quality testing, fundraising, and more. She is working her final co-op term with Back to the Sea as Events and Communications Coordinator.