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Gray FishTag Research Findings from Swordfish Tagged in 2021 and Beyond

Gray FishTag Research tagged three swordfish in 2021 and the tracked tags found interesting behaviors of the fish that generally sees deeper waters. Their tagging program is the world’s most extensive cooperative fish tagging and research program that works closely with professionals.

Kicking off in 2021 in collaboration with NOAA, the Gray FishTag research (GFR) team deployed three Wildlife Computer MiniPSAT tags to track the migration and behavior of swordfish. 


GFR is an essential tool for promoting the sustainability of marine game fish and increasing public resource awareness. The program collects information in real-time, producing valuable scientific data directly from fishermen in every part of the world. In addition, it connects professional fishermen and angling enthusiasts with the scientific community, which is interested in relevant data.


“We work with many recreational anglers who have an interest and passion for a particular fishery and would like to know more about their migration and growth,” said Roxanne Willmer from Gray FishTag Research. “We offer tagging supplies for tax-deductible donations to recreational anglers.”


The satellite tagging efforts are much different than GFR’s tagging program efforts. First, the highly technical satellite tags are extremely costly, and you must have the proper software to analyze the data collected. The research team deploys those.


“Our green spaghetti tags [MiniPSAT tags], that are used by captains and anglers, have a preprinted tag number that matches a tag data card,” said Willmer. “Once that tag is deployed, the tag data card is completed, and the information is entered into our database. Should the fish get recovered, we will compare the original data to the recovery data and determine the distance traveled and growth of that particular fish and share it.”


The first tag in the swordfish series was sent out with Captain Nick Stanczyk aboard the Broad Minded offshore Islamorada, Florida, on Feb. 9, 2021. The tag was released roughly 69 nautical miles off Fernandina Beach, Florida. This tag was discharged on Sept. 10, 2021. The 53-inch, 65-pound fish was free for 213 days.


The second tag was sent out with Captain Chris Koulouvaris on May 1, 2021, offshore Fort Lauderdale, Florida, and was released 38 nautical miles offshore Grand Cayman Islands. This tag was released on Dec. 29, 2021. The 80-inch, 240-pound fish was at large for 242 days.


The third tag was sent out on May 1, 2021, with Captain Bouncer Smith and Baron Libasci offshore Fort Lauderdale, Florida, and the tag was released offshore of Novia Scotia. This tag was released on Nov. 3, 2021. The 72-inch, 120-pound fish, was tracked for 180 days.


The tags clarified several exciting findings. The team verified that swordfish travel for 12 hours from the surface to the depths in daylight and darkness every day and everywhere. It was found that the fish dive directly to the bottom during daybreak and ascend to the surface at dusk. The tags found a complete migration in the Gulf Stream to the Grand Banks and through the Caribbean. The fish were tracked moving to deeper depths during the day when the fish moved into an area where the temperature at depth was warmer. The research proved that it is definite that water temperature plays a significant role in where the fish lives. Several basking occurrences seemed to be correlated only with minimum temperature. There were four occurrences where the fish was basking at the surface. In addition, the fish redirected into slightly deeper depths during the full moon. These fish maintained a depth of 50-300 feet at night and lived within 300 feet of the bottom during the day due to the moon phase. Furthermore, it was found that moonlight determined how close to the surface the fish went at night.


GFR is a non-profit organization that operates an international and fully interactive fish tagging program powered by the world’s largest network of fishing professionals consisting of approximately 10,000 charter boat captains and mates. GFR is the world’s most extensive cooperative fish tagging and research program. The top sportfishing charter captains and mates power it. The GFR model is to work closely with charter sportfishing professionals. Most charter professionals are on the water more days than not and engage with countless global anglers.


To learn more about Gray FishTag, to become a fish tagger, or to track tagged fish, please visit

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