Dolphinfish, also called mahi-mahi and dorado, are one of the most important offshore recreational species in the Caribbean and Atlantic. In Puerto Rico, this fish is the most landed in terms of weight of any other species of its kind. This means that dolphinfish are not only a major protein source but sustain a burgeoning sport fishing industry that provides essential income to the island through both indirect and direct costs. It is likely that the same is true for many Caribbean island nations and countries too. It’s no wonder then that Wessley Merten, Ph.D., student in the department of marine sciences at the University of Puerto Rico in Mayagüez has focused his doctoral research on the dolphinfish.
Merten has long been fascinated with this fish species. He’s shared much of his original research over the years in a number of internationally respected peer-reviewed journals. Topics covered in these articles have ranged from population studies and daily diving behavior to migration. Yet not everyone is going to seek out this information on the internet, subscribe to the journals or get a complete understanding because of the technical scientific terminology. Therefore, Merten decided to add a little Hollywood. His short documentary: ‘A Journey Pelagic’, premiered as an official selection at the 2014 Rincon International Film Festival in April.
“I refer to this project as my ‘film dissertation’, or the visually entertaining and scientifically accurate counterpart of my Ph.D. dissertation,” Merten explains. “I take my dissertation results and portray them in animations and through interviews. Some of the messages delivered, for example, are that the dolphinfish around Puerto Rico are actually a single genetic population that occurs as different seasonal runs between the north and south coast. In addition, migration data suggests a westerly trend towards Hispaniola and points further to the west such as the Turks and Caicos, Bahamas, and United States.”
Dolphinfish are annually landed in 35 exclusive economic zones in the western central Atlantic. This means it’s necessary to build a thorough understanding of their migration in order to manage and conserve the species multi-jurisdictionally and internationally. In the future, and to allow a more thorough description of migration, Merten hopes the conventional mark and release program can expand to the southern Caribbean Sea.
Research presented in Merten’s film was first collected in 2002 when the first dolphinfish was tagged and released off Charleston, South Carolina. Since then, the Cooperative Science Services LLC., Dolphinfish Research Program formed by fishery biologist Donald Hammond, has recruited hundreds of sport fishermen who have released thousands of dolphinfish and subsequently reported recaptures when and where they have occurred. To this extensive database, Merten undertook 61 fishing trips around Puerto Rico and interviewed renowned marine scientists and local fishermen in order to produce the images. He ultimately put together this film for the public to see, learn from and enjoy.
“Without the assistance of the sport fishing community this research and the production of this film would have never come to fruition,” Merten says. “Aside from using conventional mark and release techniques, some sport fishermen volunteered their time and vessels to assist Dolphinfish Research Program field biologists to deploy pop-up satellite archival transmitters to investigate the diving behaviors of these pelagic predators. Since 2004, 15 satellite tags with a price of $4,000 each have been deployed on these fish adding to our knowledge of their vertical movements.”
Caribbean sports fishermen interested in this research can assist by visiting www.dolphintagging.com to sign up for a free tagging kit to tag and release small healthy dolphinfish. Fishermen that release 20 small dolphinfish can qualify to win rod and reel outfits, Costa Del Mar prize packs, and more.