Giant Atlantic bluefin tuna, highly prized and seriously overfished, are being dealt another powerful blow as prime spawning habit in the Gulf of Mexico is being overwhelmed by oil and toxic dispersant chemicals.
Though there are several populations of Atlantic bluefin, which spend much of the year in the North Atlantic and can weigh up to 1,400 pounds, the largest fish are produced from the stock that spawns in the Gulf of Mexico. Those tuna spawn on the frontal edge of the Loop Current, where a shelf break occurs, not far from the spill site."Unfortunately, where the oil spill is occurring is essential bluefin spawning habitat," Barbara Block, a scientist and tuna expert at Stanford University's Hopkins Marine Station, said in a blog post. "These are places that are the most important in our waters to protect."
Block continued: "Imagine a fish with a reproductive strategy where it has to grow from a tiny egg to a 225-pound fish, and then once mature, it goes to spawn in the Gulf of Mexico for 4-6 weeks. If that's your strategy for reproduction, you'd better hope that your spawning ground is just like you left it the year before--warm and clean."
The Hopkins TAG team spent five years working in the Gulf of Mexico trying to establish critical spawning habitat. Research was often carried out as oil-exploration boats blasted with equipment trying to detect the presence of oil, and Block wondered what affect that was having on the many species of fish that utilize Gulf waters.
Now those trying to conserve beleaguered fisheries have more important concerns.
-- PTOGraphic shows the track from an 8-1/2-foot Atlantic bluefin tuna that was tagged off Nova Scotia. It swam into the Gulf of Mexico, spent several weeks in the spawning area, then departed (yellow track). The dark blob off Louisiana is the estimated coverage area of the oil spill as of May 3. Credit: Hopkins Marine Station