What is the Big Rock, exactly?

Newcomers to the $4.74 million billfish tournament might imagine a gigantic rock sticking out of the ocean somewhere offshore, but that’s not it.

In reality, there is no “rock.” Instead, the location is a hard bottom stretch of water approximately 35 miles southeast of Morehead City in a sweet spot of the Gulf Stream and the continental shelf.

This dividing line between the warm Gulf and colder coastal waters offers world-class fishing for once-in-a-lifetime trophies like blue marlin.

Anglers in the 64th annual Big Rock Blue Marlin Tournament are looking for spots on or west of the “break,” where the ocean goes from a gentle slope to a steep incline. That’s where they’ll find the “Big Rock,” a fishing hot spot with water depth ranging from 180 to 500 feet.

Characterized by a series of ledges, peaks and plateaus, the location covers an area of about 8-10 miles long by 1 mile in width. It serves as a haven for small reef fish, the type that attract the larger fish that blue marlin feast on.

The topography is unique and conveniently located for anglers. Typically, the Pacific and Atlantic varieties of blue marlin are found in warm, equatorial waters. They are not usually found close to land unless there is a deep drop of 500 to 1,000 fathoms, like the Big Rock.

The dramatic change in elevation abuts the Gulf Stream, which crosses the area of the Big Rock on the Hatteras Abyssal Plain along the continental shelf. In turn, the strong currents of the Gulf Stream transport relatively warm water northward along the southeastern United States slope.

Over centuries, the current has cut deep into the ocean floor as it veers away from the coastline and moves northeast in the Atlantic Ocean.

The Gulf Stream originates in the Gulf of Mexico, strengthening upstream of Cape Hatteras, where the Florida Current ceases to follow the continental shelf.

According to a study published by the University of Miami Rosensteil School of Marine and Atmospheric Science, “The transport of the Gulf Stream nearly doubles downstream of Cape Hatteras at a rate of 8 Sv every 100 km. It appears that the downstream increase in transport between Cape Hatteras and 55 degrees west is mostly due to increased velocities in the deep waters of the Gulf Stream.”

The current also moves east to west from summer to winter, even varying in volume of water carried. The best way to tell where the Gulf Stream is located at any given time is to refer to satellite surface temperature (SST) charts, with the spikes in temperature revealing the location of the current.

(Send comments or questions to or follow him on Twitter @zacknally)

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