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Expanding ocean dead zones are shrinking marlin habitat
Scientists sound an alarm that expanding ocean dead zones are shrinking the habitat for high-value fish such as marlin in the tropical northeast Atlantic Ocean. As dead zones expand, marlins, other billfish and tunas move into surface waters where they are more vulnerable to fishing.
Blue marlins and many other billfish are high-energy fish that need large amounts of dissolved oxygen.
Dead zones are areas in the ocean where oxygen levels are so low that most fish cannot survive over the long term.
Blue marlins and many other billfish are high-energy fish that need large amounts of dissolved oxygen. By comparing the movement of the blue marlins and the location of low-oxygen areas, scientists have shown that blue marlins venture deeper when dissolved oxygen levels are higher and remain in shallower surface waters when low dissolved oxygen areas encroach on their habitat from below.