U.S. East Coast | Dolphinfish Research Program | Mahi-Mahi | Mahi | Dorado | Dolphin | Dolphinfish
mahi mahi, dolphinfish, dolphin, dorado, fisheries, FADs, tag and release
mahi mahi, dolphinfish, dolphin, dorado, fisheries, FADs, tag and release
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U.S. East Coast

U.S. East Coast Movements – July 2020

Since May, 668 dolphin have been tagged along the U.S. East Coast for the Dolphinfish Research Program (DRP), and 24 of those fish have been recaptured as of today.  This represents an overall recapture rate of 3.5%, which is high compared to previous years (2.1% in 2018 and 2.2% in 2019).  Considering only fish tagged and released in June in the Florida Keys over the past three years, the recapture rate for those fish was 2.6% in 2018, 2.9% in 2019, and 4.5% this year.  What can explain the high recapture rate this year for dolphin tagged in the Florida Keys?  Does this mean more anglers are fishing this year? That there are less dolphin or dolphin habitat (sargassum) moving through the region? Or, is it a combination of those factors?  We have heard reports from some fishermen that the pandemic has reduced the number of trips they make in a year, but for others, they are fishing more than ever.  We have also received mixed reports about the run of dolphin through the Florida Straits in that it seems the dolphin did not show up and there was a lack of large sargassum patches.  Another factor that could explain the high recovery rate is proper tagging protocols followed by DRP participating vessels.  By tagging vessel, WamJam has a 5.9% recovery rate with 5 of the 84 fish they tagged in June recovered.  Killin’ Time II has a 5.1% recovery rate (17 recaptures from 327 tagged and released).  Last year, WamJam had a .7% recovery rate and Killin’ Time II had 5.3% recovery rate.  Therefore, the uptick in higher overall recovery rate could be simply be due to better tagging protocols used by WamJam.  But, another vessel, Slam Em’ Back Captained by Jay Reid, only tagged six fish and one of those fish was recovered (a 16% recovery rate).  Data such as these collected in association with the DRP are useful in comparing past, present, and future trends for dolphin and are only made possible through the dedication of anglers such as you. 

Figure 1 - July 2020 Florida Keys to South Florida dolphinfish mark and recapture locations and minimum straightline arrows between sites. Numbers indicate days at liberty. Red numbers indicate recapture locations for fish that were tagged in the same school at the same location. The 200-meter bathymetric contour is indicated with a yellow arrow.
Figure 2 - July 2020 Florida dolphinfish mark and recapture locations and minimum straightline arrows between recapture sites off North Carolina and New Jersey. Numbers indicate days at liberty. The 200-meter bathymetric contour is indicated with a yellow arrow.

New Dolphinfish Recoveries

Washington to Veatch Canyon

Captain Gary Gambarani and angler Bill Harrington aboard Easton Pool tagged and released a 20″ dolphin in Washington Canyon off Maryland on July 25th, 2020. On September 10th, after weeks of consistent winds held boats back from venturing to the canyons off Rhode Island and Massachusetts, Captain Stephen Viglas recaptured Easton Pool’s fish in Veatch Canyon. This is the 11th within-region Mid-Atlantic Bight recovery for the Dolphinfish Research Program (DRP) but the first canyon-to-canyon northeasterly movement spanning nearly the entire region. When compared with other recoveries reported within Poor Man’s and Wilmington Canyon, mostly from tagging efforts lead by Captains Chris and David Jobes and angler Will Jobes aboard Pair of Docs, the average movement rate of this new recovery is twice as fast as the previous 10 recaptures (6.65 mpd versus 3.36 mpd). This new recovery is a stark contrast to the lingering movements observed within Poor Man’s and Wilmington Canyon and merits the need to tag and release more fish within this region to showcase connectivity between canyons and the movement of dolphin biomass within the region. For this particular recovery, the recapture length is unknown but given the time at large and the average growth rate observed for the program it is likely the fish grew 4” and put on nearly 1 ¾ pounds while at liberty. In the image to the left the numbers represent days at liberty for 7 of the 11 recoveries.

Straight-line distance between tag and recapture sites = 312.59 miles; Straight-line movement rate = 6.65 miles per day; Days at liberty = 47.

St. Croix to the Dominican Republic

Captain Colt Cook and angler Duncan Wright aboard Hook n Cook tagged and released a 20″ dolphin north of St. Croix in the southwestern portion of the Anegada Passage on August 3rd, 2020. On September 23rd, 2020, artisanal fishermen Alido Baez of Bayahibe, Dominican Republic, recaptured Hook n Cook’s fish aboard La Fiera, which had grown 5″. This is the 11th within-region Caribbean Sea conventional recovery and first from north of St. Croix to south of Saona Island, DR, spanning the entire USVI/PR continental shelf corridor to the southwestern edge of the Mona Passage. When combined with the other recoveries reported south of PR and DR since 2011, the average movement rate is 8.93 miles per day. In the image to the left the numbers represent days at liberty for 7 of the 11 recoveries. The only other recovery generated from the Anegada Passage was tagged and released aboard World Class Anglers by Captain Josh Slayton and was recaptured in the northwestern portion of the Mona Passage by Captain Matthew Bierley, showing that fish can move through the Mona Passage from the Caribbean Sea toward the Tropical Atlantic.

Straight-line distance between tag and recapture sites = 257.58 miles; Straight-line movement rate = 5.05 miles per day; Days at liberty = 51; Growth rate = .098″/day or .68″/week.

U.S. EAST COAST RETURN MIGRANTS

Click here to read an article about U.S. East Coast return dolphin migrants.

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