Climate change takes habitat from big fish, the ocean’s key predators. Fishermen haul tuna in Santa Maria, island of Sal, Cape Verde, on Aug. 25.

This is because when a fish dies in the ocean it sinks to the depths and sequestrates all the carbon it contains with it. This is a form of 'blue carbon'. Big fish are about 10 to 15 percent carbon.

Join NBC Connecticut and Mystic Aquarium for the Ocean Commotion Gala on Saturday, Sept. 20 from 5 p.m. to 11 p.m. at Mystic Aquarium.

Over the last 70 years, large ocean fishes like tuna and marlin have been recovering from overfishing. ... Sharks face rising odds of extinction even as other big fish populations recover.

This year's marine heat waves and spiking ocean temperatures foretell big changes in the future for some of the largest fish in the sea, such as sharks, tunas and swordfish. Latest U.S.