The Loop Current

Know It Well

FSF Staff July 17, 2012

Spanning a distance of approximately 600,000 square miles, the expansive Gulf of Mexico is one of the most diverse and critically acclaimed bodies of water on Earth. Home to countless species of marine life, the Gulf serves as a nursery for many important fisheries while also providing migratory routes for a number of highly prized game fish. Gulf fisheries continue to be some of the most productive in the world and support thriving commercial and recreational industries. Ask locals, and they’ll swear the offshore arena is unrivaled with the option to fish reefs, ledges, wrecks and oil rigs for a wide variety of demersal and pelagic predators. However, since the Gulf is a relatively shallow basin, the extended run to deep water makes it crucial to pick and choose your days wisely.

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Powerful, nutrient rich currents are the driving force behind the fertile Gulf. Having a firm understanding of their position and movements relative to bottom structure, along with a keen understanding of optimum sea surface temperature, is key to successful offshore fishing.

Altimetry is a technique used to measure height, with orbiting satellites sending pulses to the ocean’s surface to determine precise sea surface heights.

Oceangoing seafarers of years past relied on the same prevailing currents to deliver goods along trade routes, but their knowledge was rather limited. Much of it was left to guesswork. Today, the story is much different. With the advent of advanced technology, satellites can track and monitor the exact location, speed and movement of any body of water. As a result, it’s now clear that ocean currents play a large role in the climate. Furthermore, knowledge of surface currents is also beneficial in search and rescue missions, efficient navigation, and for tracking and controlling pollutants and debris.

Driven by prevailing southeast breezes and fed by warm water from the Caribbean Sea, it is the Loop Current that controls the Gulf of Mexico. The Loop enters the Gulf through a relatively small passage between the Yucatan Peninsula and the westernmost tip of Cuba. Trillions of gallons of water continue to flow northward before shifting east and curving along Florida’s West Coast and down toward the Florida Keys. As the Loop snakes around Key West, former Gulf waters blend with the Florida Straits before converging with the warm Gulf Stream. The fertile Gulf Stream deposits nutrients as it continues north along the Eastern Seaboard.

The Loop Current’s precise position in the Gulf is constantly changing due to seasonal fluctuations and regional climate patterns. At times the current extends almost to Louisiana, while on other occasions it may barely enter the Gulf. As it flows northward, the leading edge of breaks and eddies meandering off the main flow concentrate predators and prey. And fortunately for Gulf Coast crews, these bait rich eddies come closest to the Panhandle during the early summer when sea conditions are moderate.

At the turn of the century, the precise position and movements of oceanic currents were somewhat secretive amongst oceanographers and marine biologists. Nowadays, satellite-based forecasting services provide detailed information across multiple media platforms, offering clear insight into the flow of the Loop Current and its direct influence on potentially successful fishing .

While you are likely familiar with satellite images that reveal sea surface temperatures, did you know that altimetry charts can reveal the locations of current upwellings and downwellings? Altimetry is a technique used to measure height, with orbiting satellites sending pulses to the ocean’s surface to determine precise sea surface heights. When it varies, the results are convergence zones—areas that attract plankton, baitfish and the game fish that feed on them.

Upwellings drive nutrient rich water toward the surface from the deep, while downwellings flush lifeless surface water toward the ocean floor. As waters warm their volume increases, forcing water levels to rise. Conversely, cooler waters are not as dense and have lower sea surface heights. These changes in SSH are interpreted by satellite data and used to decipher the location and movements of currents and eddies in the Gulf. Anglers heading over the horizon shouldn’t ignore these likely areas or they miss the bite.

Heading offshore from Pine Island to Pensacola is a major undertaking that requires careful planning and extensive preparation. With fuel at an all time high, it’s nice to know anglers have technology on their side. With subscription services like ROFFS (roffs.com), Hilton’s (hiltonsoffshore.com), Terrafin (terrafin.com) and RipCharts (ripcharts.com), captains now have the ability to pinpoint fish attracting features long before they ever step foot on the boat. With a firm understanding of the world’s oceans it’s more clear than ever that our seas have no boundaries. As a result, protection of global ecosystems requires worldwide conservation efforts.

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