According to Wikipedia, the Atlantic bluefin tuna, also known as northern bluefin tuna or giant bluefin tuna (for those exceeding 330lbs) is heavily fished for two main reasons: "Throughout recorded history, the Atlantic bluefin tuna has been highly prized as a food fish. Besides their commercial value as food, the great size, speed, and power they display as apex predators have attracted the admiration of fishermen, writers, and scientists."
The Atlantic Bluefin tuna is the largest species of the Scombridae family and is known to reach speeds of 43mph in the ocean. While most of the Atlantic Bluefin tuna range between 500 to 1000 lbs, some are known to tip the scale at 1,500lbs!
Per reports, the largest Bluefin tuna ever caught was in 1979 and weighed a whopping 1,496lbs: "Not only is Ken Fraser’s bluefin the biggest tuna ever recorded by the International Game Fish Association, it is also one of the most iconic records of all time. He landed the world record bluefin tuna on October 26, 1979, fishing with Capt. Eric Samson aboard Lady and Misty out of Port Hood, Nova Scotia. And get this, Fraser needed just 45 minutes to bring the largest tuna ever caught close enough to gaff after it ate a trolled mackerel."
In Massachusetts, the record for largest Bluefin tuna caught goes to Marlene Goldstein who reeled in a massive 1,228lbs tuna back in 1984.
Bluefin tuna is a popular offering in sushi restaurants and provides lucrative business for the raw fish market in countries like Japan. One article cited that the average price of a single Bluefin tuna fish in Japan is as high as $10,000.