Fishing the break

What exactly do fishermen mean when they say they are “fishing the break?”

Quite simply, the area where the ocean bottom begins increasing its slope is the break. The floor inshore of the break is the Continental shelf, and below the break is the Continental slope. The ocean bottom changes dramatically at the break, and the combination of structure and current holds bait and attracts predator fish.

Most charts of the North Carolina coastline show the break at somewhere deeper than 30 fathoms (180 feet) but generally less than 100 fathoms (600 feet). Some sources have it following an average depth of 72 to 77 fathoms (433 to 460 feet) and identify the change in the slope of the sea floor slope as a remnant of past ice ages, when sea level was significantly lower.

The angle at which the sea bottom falls away is much steeper on the slope. The average angle on the shelf is a degree or less, while the slope averages approximately 3 to 4 degrees. However, there are places where it is as shallow as a single degree and others where it’s as steep as 10 degrees.

South of the Big Rock, the 30- and 100-fathom lines are much closer together than north of the Big Rock. This indicates a steeper slope to the south and a shallower slope to the north.

The gradient of the Continental shelf and slope is lowest off stable coasts without major rivers and highest off coasts with mountain ranges and narrow continental shelves. Most Atlantic Ocean slopes are shallower than Pacific Ocean slopes; the shallowest slopes are in the Indian Ocean.

In every ocean, the break and continental slope have areas with sheer rises and canyons that are formed by the forces of plate shift, sea-floor sedimentation and other forces of geology and nature. These areas interrupt the prevailing currents and concentrate baitfish. The sheer southwest face of the Big Rock is a prime example off North Carolina’s coast.