A Goliath Dilemma: Feeding a voracious appetite

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One of the charges most often used against goliath grouper, is that their insatiable appetite has had a negative impact on other species of reef fish, most notably snapper and other, smaller species of grouper—as Scott Butherus reports in this article for marconews.com.

While goliath are opportunistic predators that will consume just about anything it can fit into its considerable jaws, studies have shown that isn’t necessarily the case.

“The perception that they are having a negative or adverse impact on other fish populations or habitat is not supported by scientific evidence,” said Bryan Fleuch, the director of the Collier County Sea Grant Extension.

Research shows that about 85 percent of a goliath grouper’s diet consists of crustaceans. The remaining 15 percent primarily is made up of slow-moving fish such as burrfish, catfish and toadfish. In one study that looked at the stomach contents of over 200 goliath grouper, researchers found no grouper, and only a small percentage (three percent) of snappers.

Goliath actually can have a positive effect on co-inhabitants of the reefs.

According to Fleuch, goliath grouper are thought to play a role as “ecosystem engineers” that can modify their environment, and create habitat for themselves and other species. Goliath can help expose limestone bottom when they lay under ledges or on the open sea floor, which then can be colonized by other marine life such as corals, anemones and sponges, as well as the organisms that depend on them.

Because of their size, goliath attract huge clouds of baitfish that school around the massive fish for protection from other predators.

While this is good news for the reef fish, the rebound of the goliath population may have a negative impact on shellfish like crabs and lobsters.

“There aren’t many lobster around here unless you go way offshore where there aren’t many of the goliath,” said Capt. Mark Garcy, who operates Spear1up charters. “Talking to some of the old-timers, back in the day there was fairly decent lobstering right off shore here, but nowadays, they are pretty much extinct.”

GOLIATH GROUPER

Scientific name: Epinephelus itajara

Size: Up to eight feet long, 800 pounds (state record: 680 pounds)

Life span: 30-50 years

Diet: Crustaceans and slow, bottom-dwelling fish

Habitat: Can be found in the Atlantic Ocean, Caribbean Sea and Gulf of Mexico. Adults inhabit nearshore reefs and rock ledges; juveniles in mangrove and brackish water estuaries.

Of note: The species were commonly referred to as “Jewfish” until 2001, when the name was changed by the American Fisheries Society. Although the origins are debatable, it is believed that the original moniker dates back to the late 1600s when the large fish was a kosher favorite for Jewish settlers in Jamaica.

For the original report go to http://www.marconews.com/news/2013/jul/20/a-goliath-dilemma-feeding-a-voracious-appetite/

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