General Patterns of Dolphinfish Movements
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During the course of this research which has spanned more than a decade, general movement patterns have emerged in many areas of the western North Atlantic Ocean, Caribbean Sea and Gulf of Mexico. The number of tag recoveries occurring each year in certain areas creates a mass of overlapping lines, obscuring individual movements. For this reason, beginning in 2014, movements of recovered fish that replicate previous travels will be described in spreadsheet form with a reference to a specific route depicted on one of five following maps.
(Click on maps to get route descriptions.)
- Recaptures have shown dolphin continually move northward along the U.S. Atlantic coast riding the ocean currents, disappearing for varying time periods before showing up in warm tropical regions.
- East Coast fish tagged one year and recovered the following winter or spring in the Caribbean Sea or distant areas of the North Atlantic Ocean suggest the existence of multiple routes that dolphin use to move south during the cold months.
- Some fish may make a circum-Atlantic migration that encompasses 8,000 miles or more. Such travel would only require an average daily movement of 22 miles.
- Fish may exit the Gulf Stream off Cape Hatteras, North Carolina, traveling southeast to catch a southerly counter-current that will carry them to warmer southern waters.
- Those fish that travel to the Atlantis Canyon area off Montauk, New York, could turn southeast, traveling beyond the island of Bermuda before catching a southerly current back to the tropics.
- Dolphin probably use numerous routes based on primary ocean currents as well as intermittent currents that carry them east and south on their return to the tropics.
While dolphin are caught off the southeastern U.S. coast throughout the year, there is a definite seasonal occurrence. Data indicate that the majority of these highly migratory fish are constantly moving northward along the U.S. Atlantic coast regardless of season. Dolphin begin increasing in numbers in the Straits of Florida off the Keys in late March and April, building in numbers into late May or June when they normally peak in abundance. Off South Carolina, dolphin typically reach their peak abundance from May to early June. Peak abundance off North Carolina commonly occurs in June, while the peak abundance in the Mid Atlantic Bight normally occurs from late July to early September.
These fish are entering the Straits of Florida from the west by way of the Loop Current in the Gulf of Mexico and from the east traveling the Old Bahamas Channel. These fish move northward along the east coast of Florida where heavy fishing pressure on the western side of the Stream harvests a large proportion of the fish. This fishing activity appears to push surviving fish to the eastern side of the Gulf Stream where they remain as they travel northward to North Carolina and the Mid-Atlantic Bight.
Dolphin moving northward from the Straits of Florida are joined by fish traveling from the eastern side of the Bahamas Bank. Rounding the northern tip of the Bahamas Bank, eastern Bahamas fish begin entering and even crossing to the western side of the Gulf Stream at a point east of Fort Pierce Inlet, Florida. Fish from the eastern Bahamas serve to replenish the dolphin stock on the western side of the Gulf Stream for their northward journey along the U.S. Atlantic coast. Fish coming out of the Bahamas could be the primary source for dolphin caught off the Carolinas.
Fish tagged off South Carolina on the western side of the Gulf Stream have exhibited a much slower rate of northward travel than their Florida counterparts. The reason may be the presence of two intermittent gyres found on the western wall of the Gulf Stream off the Carolinas. Dolphin could enter these large rotating water masses and swim in circles for days, weeks or even months before exiting to continue their northward trek. Fish moving up the eastern side of the Stream would by-pass these obstacles and not be slowed in their northward movement.
It is off North Carolina that dolphin coming out of Florida are once again caught in large numbers by recreational anglers, likely because the Gulf Stream comes much closer to landfall in this area. It is unknown what portion of the dolphin population departing North Carolina continues northward into the Mid-Atlantic Bight and what segment turns more eastward, moving out into the open North Atlantic.
Dolphin probably use a large number of routes to move south when they depart the U.S. territorial waters. These routes could be as long as a circum-North Atlantic trek or as short as a circle around the Grand Bahamas Bank. The route chosen will likely involve an ocean current that helps them along, even if it is only an intermittent current, and it will likely contain a good abundance of baitfish to sustain them. Dolphin tagged off the U.S. East Coast have traveled to South of the Azores Islands in the Eastern North Atlantic, Puerto Rico, Antigua, St. Kitts, Venezuela, Mexico and Cuba. Such widely dispersed recoveries question the validity of a three-stock theory currently held by fishery managers for dolphinfish in the Western Central North Atlantic Ocean.
Recoveries have also shown that dolphin will return to U.S. territorial waters. Such return visits have occurred within the same year, but most have spanned a winter. Typically, the fish is tagged during the spring or summer of one year and recovered in the next year. This does open the possibility that if fishermen release more small fish, they could be rewarded the next year with more big fish.
NOTE: Information presented here is based on a dynamic data base that is continually being updated, which can lead to new information altering our understanding of dolphinfish movements.
- 76 percent of fish tagged off Florida and later recaptured are recovered before they leave Florida.
- Tagged fish recovered before leaving Florida traveled northward at an average speed of 8.1 miles per day.
- Florida tags have been recovered along the U.S. East Coast from Brunswick, Georgia, to Montauk, New York.
- Fish recovered from North Carolina into the Mid-Atlantic Bight average traveling 21.6 miles per day.
- Fastest movement by a dolphinfish was a Florida fish that traveled 130 miles from one day to the next.
- A fish traveled from Islamorada, Florida, to Oregon Inlet, North Carolina, 835 miles, in nine days, averaging 93 miles per day.
- A fish traveled from Key West, Florida, to Cape May, New Jersey, 1,123 miles, in 23 days averaging 49 miles per day.
- Numerous fish have traveled their full East Coast range within a two-month period.
- More than 90 percent of all Florida tag recoveries exhibited a net northerly movement even during winter months.
- Heavy fishing pressure off Florida’s southeast coast removes a large proportion of dolphin present in the western side of the Gulf Stream and appears to push most of the remaining fish to the east side of the Gulf Stream where they remain during their movement to North Carolina.
- Eighty-eight percent of the fish tagged off South Carolina that were later recovered exhibited a net northward movement.
- More than 60 percent of the recoveries of South Carolina dolphin come from North Carolina.
- South Carolina dolphin traveled to North Carolina and the Mid-Atlantic Bight at a much slower pace than Florida fish, moving an average of 7.6 miles per day.
- The slower speed of travel likely results from fish entering an intermittent gyre off South Carolina where they could swim in circles for weeks or even months.
- The impact of this gyre can be seen in the recovery of a dolphin tagged off Charleston, South Carolina, that was recovered 70 days later only 19 miles from its release site. The fish was tagged and recovered on the west side of the gyre.
- Florida fish traveling the eastern side of the Gulf Stream are able to by-pass these gyres allowing them to sustain a faster movement rate.
- Fish tagged in the Bahamas have been recovered from Ft. Pierce, Florida to Montauk, New York, and even out in the North Atlantic Ocean.
- Tag recoveries from Florida and Georgia suggest that dolphin coming from the east side of the Bahamas Bank cross the Gulf Stream to its western side as they move northward along the U.S. coast.
- One fish averaged traveling at 25.8 miles per day moving from Elbow Cay, Bahamas, to a point 350 miles east southeast of Nantucket Island, Massachusetts, in 45 days.
- Dolphin from the Bahamas and recovered off the U.S. Atlantic coast averaged traveling northward at 15.4 miles per day, suggesting that some fish may travel the east side of the stream.
- These recoveries have shown that fish in this area of the Western North Atlantic cross to the U.S. Atlantic coast during spring and summer, serving to replenish the dolphin population moving up the coast from the Straits of Florida.
- The recovery of a fish tagged off Marathon, Florida, in June and recovered the next spring off Long Island, Bahamas, shows that fish will move from U.S. waters to those in the eastern Bahamas.
- Fish tagged in the Tongue of the Ocean in the central Bahamas Bank have shown a tendency to linger in this area, being recovered there as much as 51 days later.
- Tag recoveries suggest there may only be one stock of dolphinfish in the Western North Atlantic Ocean, as opposed to three currently recognized by fishery managers.
- Dolphin tagged off the U.S. Atlantic coast have shown up throughout the Caribbean Sea, being caught off Cuba, Puerto Rico, St. Kitts, Antigua, Venezuela, and Mexico at the Belize border.
- The most distant recovery report came from the Eastern North Atlantic where a Spanish commercial fishing vessel recaptured a tagged fish off the Azores Islands. The fish, released off Charleston, South Carolina, had traveled a straight line distance of 2,500 miles during its eight months of liberty.
- These recoveries suggest the existence of migration routes that carry some portion of the U.S. East Coast stock throughout the Caribbean Sea while others may travel into the Eastern North Atlantic.
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Made possible by a grant from the Guy Harvey Ocean Foundation.