In honor of World Oceans Day, I’d like to share some fascinating biology facts, as well as conservation issues surrounding the Atlantic Bluefin Tuna.

Bluefin Tuna Conservation Challenges

There are 3 species of Bluefin Tuna including the Atlantic, Southern, and Pacific. They’re most closely related to the Yellowfin and Bigeye Tunas and are native to the western and eastern Atlantic Ocean, the Mediterranean Sea, and formerly the Black Sea where sadly they are now extinct. Atlantic Bluefin Tuna is highly valued as food, especially in Japan where the highest prices are paid.

 

bluefin-tuna

Frozen Tuna at Tokyo Fish Market

 

Heavy tuna farming since the 1970’s, combined with years of overfishing, has led to decreased populations. The 2010 Gulf of Mexico oil spill disturbed an important spawning ground for these beautiful fish, also contributing to their decline.

Image courtesy of the Food and Agriculture Organization

What Atlantic Bluefin Tuna Look Like

  • With an average weight of 500 to 550 lbs and an average length of 6.5’ to 8’, the Atlantic Bluefin Tuna is one of the largest marine animals.
  • They have a long, pointed head with a large mouth and small eyes.
  • They have two dorsal fins separated by a small space (the second fin being longer), then 7-10 finlets, and short pectoral fins, which distinguish them from other family members.
  • Dramatically colored, the Atlantic Bluefin is dark blue on top and gray underneath, with bright yellow caudal finlets and gold coruscation (reflective sparkle).
  • They possess a translucent covering on their head called a pineal window for navigating over thousands of miles.

What They Eat and Who Eats Them

  • Atlantic Bluefin Tuna are aggressive predators with a diet of smaller fish, crustaceans, squid, and eels.
  • Their predators include killer whales, pilot whales, sharks, and seabirds.

Bluefin tuna, Thunnus thynnus

Facts About Atlantic Bluefin Tuna

  • Strong and muscular, the Bluefin Tuna is one of the fastest fish in the sea with fascinating adaptations for swimming at speeds over 40 MPH!
  • They have very unique adaptations that allow for this including the ability to retract their dorsal and pectoral fins into slots to reduce drag! Their bodies also remain rigid when their tails move, further increasing their speed and endurance.
  • The Atlantic Bluefin is warm-blooded but also has a highly developed ability to thermoregulate, allowing them to endure colder waters than many of their family members.
  • Females produce up to 30 million eggs.
  • They spawn together in such large groups, they can sometimes be seen by air.
  • The eastern populations are thought to mature a year or two earlier than western populations.

Learn To Sketch A Bluefin Tuna

In celebration of World Oceans Day in June, I’d like to invite you to join me for a live sketching tutorial over on my Facebook Group; Christine’s Nature Sketching Challenge on June 23rd. The Bluefin Tuna is one of the fastest fish in the sea with fascinating adaptations for swimming at speeds over 40 MPH! Learn all about this beautiful but increasingly threatened species with this sketching tutorial during June when we celebrate World Oceans Day.
So join me live on our FB group where I’ll demo how to draw the Bluefin Tuna while we’re also learning about this iconic ocean fish. It happens June 23rd at noon Pacific time. No worries if you can’t join us live, the video will remain on the page going forward but when you join live you can ask questions and submit your sketches for prizes!

Learn More about Atlantic Bluefin Tuna and their Conservation

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