General Movement Patterns | Dolphinfish Research Program | Mahi-Mahi | Mahi | Dorado | Dolphin | Dolphinfish
Dolphinfish Research Program
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General Movement Patterns

Dolphin Movements by Geographic Location

The Dolphinfish Research Program is constantly gathering new data relative to all the locations that anglers tag dolphin for the program.  There are five regions, however, where we have already acquired enough data to begin to analyze the species annual, semi-annual, and/or seasonal movements.  Those regions include the Bahamas, Eastern Tropical Pacific Ocean, Caribbean Sea, U.S. East Coast, and Florida (icons left to right above).  You can view articles and data published on the movements of dolphin in those regions by clicking the icons above.

New Recoveries in the Dominican Republic
October conventional dolphinfish recoveries reported at fish aggregating devices along the north coast of the Dominican Republic. Black Numbers = Days at Liberty; Stars = Recovery Sites; Yellow Ovals = Tagging Sites

Since 2008, our tagging program has documented dozens of dolphin movements for fish tagged within the U.S. Caribbean Sea as well as  those tagged along the U.S. East Coast that have been recovered in the northeastern Caribbean Sea (click here to read about that work).  This past month, thanks to the effort of angler Jeffrey Liederman and the Sandman fishing team, we received our first four recoveries for dolphin tagged and released within Dominican Republic (DR) waters, which provided the first glimpse at in-country movements and dolphin fishery dynamics along this portion of the Greater Antilles.  When averaged, these four recoveries together indicate a swift rate of 18.6 miles per day toward the northwest.  This is much faster than the combined movement rate for fish recovered along the north coast of Puerto Rico (PR), which equates to less than 5 miles per day. One factor that could be responsible for this

Angler Jeffrey Liederman showcases one of the 69 dolphin he has tagged aboard Sandman off the Dominican Republic since the last week of September. Pic: Sandman

difference is along the north coast of PR there are five major rivers that pour into the tropical Atlantic, whereas there are only two along the north coast of DR, both of which are tucked into large bays which may reduce the potential flotsum and local variation in currents that may influence the movements of dolphin offshore. Another major difference between the dolphin fishery along the north coast of PR versus DR is the abundance of fish aggregating devices (FADs) off the coast of DR. Each dolphin recovery off DR this past month was both tagged and recaptured at a moored fish aggregating device. The existence of likely

Conventional mark and recovery movements for dolphinfish off the north coast's of Puerto Rico and the Dominican Republic. Black Arrows - 2021 Movements / Grey Arrows 2008-2020 Movements

hundreds, if not thousands, of these structures along the north coast of DR, could be the reason why Sandman’s recovery rate is an astonishing 6.67%, higher than even Killin’ Time II’s and WamJam’s historically high recapture rates observed during June and July in the Florida Keys in past years. A major difference between these recoveries is that all recoveries within the Keys are reported by recreational or charter fishermen while the fish reported this past month off DR were all small-scale artisanal anglers. Recorded commercial landings for the Dominican Republic have been highly variable since 1967, with abnormally high landings recorded in 2007 (figure above). Since 2014, however, a steady rise in commercial landings has put the DR back to one of the top landing commercial countries in the region, higher than U.S. Atlantic commercial landings, and the fact that four individual artisanal anglers reported recoveries over the first two weeks of October at four different FADs highlights the need for increased data collection on this species and the FAD fishery within the DR to ensure a sustainable dolphinfish fishery for both the country and the region.

Entire time-series of dolphinfish landings from the Food and Agricultural Organization's global capture production dataset for the Dominican Republic.
Gulf of Mexico - Upper Florida Keys Recovery
Black text = 2021 recovery. Grey text = 2012 recovery

September 2021 – Each year, recoveries of dolphinfish tags follow a somewhat predictable pattern given the number of tag deployments per location and the fishing effort in those areas.  A primary example are dolphin tagged in the Florida Keys and recovered off South Florida.  This year, 41% of tag recoveries fall into this category, and over the history of our program, 15% of all recoveries pertain to short-term movements between these areas.  This data is useful for a host of scientific and fishery management uses (click here for articles on that) but beyond the scope of this article, each year, rare tag recoveries occur whose details unlock a multitude of new comparisons, analyses, thoughts, and theories about the movements of this epic gamefish.  With an annual average of only  32 dolphin tagged in the Gulf of Mexico (GOM) over the past two decades, recoveries generated from the GOM are statistically low (now 3 of 561 fish) but the revered Whoo Dat fishing team beat the odds this year.  Recently, Captain Charlie Rogers of Against the Grain fishing charters based out of Key Largo, Florida, reported Whoo Dat’s tag number for a fish they tagged 95 miles south of Grand Isle, Louisana, on July 20th, 2021.

Against the Grain client catch on 9.12.2021 that included the fish tagged by Whoo Dat. Pic: C. Rogers

Coincidentally, a surface drifter (4201703) was deployed six days after and only 30 miles south of where Whoo Dat tagged the 24″ dolphin, which provides a potential route this fish may have taken to swim to the Florida Keys (and possibly beyond if it had not been recovered). A swift surface drifter movement from the Loop Current to the North Atlantic in just 28 days raises the question of whether dolphin swim through the system at the same pace. We do not have an

Surface drifter track July 26th, 2021, to August, 22nd, 2021

example of that type of movement, but our fastest single day movement is 120 miles, fastest movement between south Florida and North Carolina is 7 days, and fastest movement from the Florida Keys to the Mid-Atlantic Bight in 10 days suggest that it is possible. What this recovery does show is that a 24″ fish tagged south of Grand Isle, Louisiana, grew 6″ in 54 days when it was recovered off the Upper Keys. This supports our position that management for dolphin along the U.S. East Coast should both include dolphin that occur in the U.S. GOM, which are connected on very short time-scales, and establish an increase in fish reproduction and biomass by extending the SAFMC’s 20″ minimum size to the GOM, so that dolphin either remain within the GOM and grow to the size of Tessa’s first dolphin (pictured above) or toward the East Coast for anglers like Against the Grain’s clients to catch like they did in early September.  And, with three new recovieres in the MAB since our August newsletter, these examples provide further evidence of how small fish tagged off the Keys can grow to larger sizes before being caught in northern areas along the eastern seaboard.  Captains Mark LaRocca, Erik Dahl, and angler

Captain Bob Felinski poses with Tessa Clague after she caught her first dolphin in the GOM off Texas this past summer. Pic. T. Felinski
Black text = recent recoveries Grey text = last month's recoveries

David Pereira are the latest to recapture tagged dolphin in the MAB.  Captain LaRocca’s fish was tagged by Captain Kevin McDermott 18 days before it was recovered.  The 20″ fish was tagged at a lobster pot 25 miles northwest of the mouth of Hudson Canyon and recaptured at another lobster pot after growing 3″ in an area known as the 100 square in Hudson Canyon, 42 miles southeast from where it was tagged.  Captain Dahl’s fish was caught with his family only 9 miles east of Barnegat Inlet, NJ, 81 days after Captain Don Gates and the Killin’ Time II fishing team tagged the fish.  After 81 days at liberty, the fish grew from 17″ to 32″.  Lastly, Captain Tim Heiser and his wife Michelle tagged and released a 15″ fish off Ft. Lauderdale on May 1st, 2021, that angler David Pereira recaptured as a 28″ fish aboard Captain Tom Randall’s charter vessel Longer Days 20 miles out of Cape Hatteras, NC, on September 8th.  Average daily growth for all fish reported in this article equates to .13″/day (.91″/week; 3.64″/month) and in three of the four examples show small young-of-the-year fish (<20″ FL) growing 3″ to 15″ in the same calendar fishing season within the Loop-Gulf Stream current system.  Click here to read more about this year’s recoveries on our regional movements page.

Dolphin recoveries since our August newsletter.
30,000 Dolphin Tagged!

August 2021 – Just under two decades ago, during a mid-April fishing trip aboard Summergirl off South Carolina, Don Hammond tagged the first dolphin for this tagging program.  Earlier this month, the Wam-Jam Fishing Team, fishing out of Marathon, Florida, tagged the 30,000th dolphin!  While surpassing our 30,000th tagged dolphin is not a scientific goal of the program, it is symbolic of our program’s history and dedication to distribute tags and tagging kits, recruit and engage anglers, and log the data to determine the movements and life history traits of this species throughout the Western Central Atlantic and Eastern Tropical Pacific Oceans.  Given the program’s stready growth in participation, which we estimate has grown to 6,000 anglers throughout our history, the level of data collection has subsequently grown,

and as a result, we have learned a tremendous amount about this species’ annual, semi-annual, and seasonal movements by tagging region (see table above).  As with most scientific studies, there remains much work to be done; for our program, the two major locations for which we have very limited data are the Mid-Atlantic Bight (MAB) and the Gulf of Mexico (GOM).  Recently, two tagged dolphin were reported in the MAB (see article here) and thankfully, this year, we have had tagging participation within both regions.  With a steady level of participation by anglers in the MAB andand GOM, we hope that over the course of the next several years, as we push toward 40,000 tagged dolphin a significant proportion of those fish come from those zones. When combined with our satellite tag deployment efforts, we can effectively fill in knowledge gaps that exist for this species which can aid in improving species management and conservation.  To learn more about our effort in the MAB, visit beyondourshores.org/mab, or to help this effort wherever you fish and reside, click here to request tags.  A special thanks goes out to the  thousands of anglers that have participated as well as the individuals, fishing industry companies, and organizations that have supported our work to achieve at this significant milestone in our history!

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