National Geographic : 2014 Jul
Groupers 109 shipwrecks and reefs, sidling together in bul- let-shaped masses, bumping and nuzzling and sounding off in the dark of night as they send up sperm and eggs to build the next generation. However successful their mating, a return to historic high numbers may be just a dream for the big fish. Koenig says exposure to mercury is having “an insidious toxic impact” on the animals. “ The adults have actual pathologies— lesions in the liver—from the levels of mercu- ry,” he says. Not only might that be partly to blame for the fish’s decline, but also it means we shouldn’t be eating these things. “If you were to catch anything over about four feet long,” says Don DeMaria, a former commercial fisherman who assists with conservation efforts, “you would have to throw it back anyway.” The mer- cury, he says, “makes it inedible.” The future of goliaths is also tied up in those mangrove nurseries, where the fish live around the trees’ tangled roots until they are about five years old. Coastal development, agriculture, and pollutants threaten these shallow-water habi- tats. The current trajectory suggests 20 percent losses of remaining U.S. mangroves in the next 50 years—devastating for young, developing goliaths, which are already reeling from unusu- ally cold winters that took out thousands of the fish from their juvenile habitat throughout South Florida. Ultimately fishermen and biologists and even government officials want the same thing: a grouper population big and vigorous enough to keep divers coming and to weather a few hooks in the water without collapsing. While the de- bate rattles on, the goliaths in question continue booming beneath the waves. The big fish, too, just want to be heard. j Goliaths hover in a strong current above the Zion Train artificial reef near Jupiter, Florida. The fish gather on wrecks and reefs by the tens or even hundreds in preparation for spawning. This behavior, which peaks during the new moons of August and September, makes them easy to catch.