GULF OF MEXICO TUNA MIGRATIONS Jorge Brenner and Valerie McNulty PHOTO © TIM CALVER PHOTO © KEVIN ARNOLD Contents ACKNOWLEDGEMENTS This report is a part of the Migratory Species Conservation Project. For more information, visit migratoryblueways.org and maps.bluewaysconservation.org. This project was made possible due to the generous financial support of an anonymous private donor, as well as The Nature Conservancy’s Global Oceans Team and Texas Chapter. The au- thors would like to thank the guidance provided by this project’s Scientific Steering Committee: Dr. Billy Causey of the Nation- Introduction 2 al Marine Protected Areas Center of the National Oceanic and Atmospheric Administration, Dr. Félix Moncada of the National Fisheries Research Center of Cuba, Dr. Frank Muller-Karger of the University of South Florida, Dr. Rodolfo Claro formerly with the Institute of Oceanology in Cuba, Dr. Ruth Perry of Shell, Dr. William Kiene formerly with the Office of National Marine Sanc- Mapping Tuna Migrations 6 tuaries of the National Oceanic and Atmospheric Administra- tion, and Dr. John ‘Wes’ Tunnell of the Harte Research Institute for Gulf of Mexico Studies at Texas A&M University-Corpus Christi (1945-2018). The authors would like to especially ac- knowledge the contributions of the scientists and institutions Key Findings and Limitations 18 that supported this project by providing datasets, comments, and reviews essential to the development of these analyses and this report (for a full list of contributors, visit migratoryblue- ways.org). Special thanks to Dr. Rich Bell, Dr. Robert Bendick, Randy Blankinship, Dr. William Driggers, Linda Elkin, Dr. Ben- jamin Galuardi, Dr. Walter Ingram, Dr. César Meiners, Dr. Todd The Way Forward 22 Phillips, Karina Ramírez, Dr. Steve Schill, Dr. Pedro Ulloa, and Lily Verdone. Illustrations and design by Valerie McNulty. Suggested citation for this report: Brenner, J. and V. McNulty. 2018. Gulf of Mexico Tuna Migrations. The Nature Conservancy, Arlington, 24 pp. THE NATURE CONSERVANCY | GULF OF MEXICO GULF OF MEXICO TUNA MIGRATIONS 1 Figure 1. Gulf of Mexico study area and commercial tuna fishing areas for the United States, Mexico, and Cuba. Commercial fisheries in the U.S. Introduction mainly target yellowfin tuna, so its adult Essential Fish Habitat (NOAA) is used as an approximate U.S. tuna fishing area here (Levesque 2011). Tuna The Gulf of Mexico large marine ecosystem (hereafter the Gulf) Fishing Areas is a biodiverse and productive international sea, booming with activity such as offshore energy development, shipping, commer- cial and recreational fishing, and tourism. Due to its geographic Project location between North America and the Caribbean Sea, it is Study Area also filled with a wealth of migratory fish, sea turtles, marine mammals, and birds that seasonally take advantage of its vast resources, habitats, and weather. However, issues arise when human activity blocks their migrations and prevents them from completing their life cycles. Migratory tunas make up 20% of the value of marine capture fisheries and over 8% of globally traded seafood (United Nations 2017). Tuna fisheries are a highly valuable resource in the Gulf for coastal economies, food security, jobs, recreation, tourism, and culture. Tuna fishing areas in the Gulf are shown in Figure 1. Eight migratory tuna species in the Atlantic have been selected This report introduces The Nature Conservancy’s toolkit for tuna as critical species for inclusion in this Gulf assessment: albacore fisheries managers and policymakers in the Gulf. The toolkit tuna, bigeye tuna, blackfin tuna, bluefin tuna, bonito, little tunny, includes spatial biophysical data layers, seasonal conservation skipjack tuna, and yellowfin tuna. planning scenarios, an interactive online mapping tool, and a fishing regulations summary. The toolkit consolidates import- Atlantic tunas are highly migratory species. In the Atlantic Ocean ant national and international information on tuna distributions, they move hundreds to thousands of kilometers connecting pop- movements, larvae distributions, threats to migration, critical ulations, habitats, and economies from the northeastern U.S. areas, and existing management and conservation actions. to Europe and west Africa. Therefore, they need to be managed domestically and internationally (NOAA Fisheries 2006). Mexico While compiling this data, the Conservancy was also able to iden- and the U.S. are contracting parties to the International Commis- tify data gaps. More fisheries data was available for United States sion for the Conservation of Atlantic Tunas (ICCAT), which man- waters than Mexico, Cuba, or international waters. Information ages tuna internationally in the Atlantic. Managers in different on migratory pathways was non-existent, and migratory tim- jurisdictions and industries have varying priorities when consid- ing information was sparse and had to be inferred from multiple ering how to manage activities and various natural resources in sources (again mostly only available in the U.S.). More data was the Gulf. Many variables affect management decisions, such as available for some species than others, due to their economic seasonal species distributions, migratory pathways and timing, value or conservation status. ongoing conservation actions, threats, habitat and ecology, use and trade, and fishing activities and regulations. However, it can These gaps and limitations are more completely described at be difficult to assess the complex interactions among these vari- the end of this report, but it is important to note when using this ables when data is limited and often not synthesized into salient toolkit that there is room for improvement and expansion as data formats or available in one location. becomes available. THE NATURE CONSERVANCY | GULF OF MEXICO GULF OF MEXICO TUNA MIGRATIONS 2 THE NATURE CONSERVANCY | GULF OF MEXICO GULF OF MEXICO TUNA MIGRATIONS 3 *A majority of the species information on this page comes from the Interna- Use and Conservation tional Union for Conservation of Nature (IUCN) Red List of Threatened Species. Threats Trade Actions EX EW CR EN VU NT LC Albacore tuna Bonito Blackfin tuna Bigeye tuna Near Threatened Least Concern Least Concern Vulnerable Thunnus alalunga Sarda sarda Thunnus atlanticus Thunnus obesus Primarily sold as a Food fish, especially important in Important sport fishery in Flor- An important fishery, pri- canned white meat tuna. the Mediterranean and Black seas. ida and the Bahamas. marily sold for sashimi. Commercial and recre- Commercial and recreational Commercial and recreational fishing. Commerical and recre- ational fishing; bycatch fishing; bycatch of Yellowfin Mexico has landed the highest tonnage of ational fishing, bycatch of of swordfish fisheries. tuna fisheries. Cuba has ceased this species; it represents the second most the Skipjack and Yellowfin reporting landings data for this captured tuna in Cuba. tuna fishery. It has a total allowable species. It has a total allowable catch A total catch of catch (TAC) of 29,900 No specific measures in (TAC) of 29,900 tons for the 85,000 tons has tons for the south Atlan- place. tic stock.* south Atlantic stock.* been recommended in the Atlantic. Bluefin tuna Little tunny Skipjack tuna Yellowfin tuna Endangered Least Concern Least Concern Near Threatened Thunnus thynnus Euthynnus alletteratus Katsuwonus pelamis Thunnus albacares Highly sought-after deli- An important food and Important commercial cacy for sushi and sashimi economic resources for Primarily sold as canned tuna. species for the raw sashimi in Asia (WWF, 2018). coastal communities. market (WWF, 2018). Constitutes 60% of commercial Commercial and recre- Overfishing. tuna catch globally; difficult to The main species targeted by ational fishing; unreported assess the impacts of fishing on commercial fisheries in the U.S. or underreporting catches Taking Bluefin tuna in the Gulf is populations due to high and vari- and the only tuna commercial- to ICCAT. prohibited yearround. ICCAT rec- able productivity. ly fished in Mexico. ommends long-term larval studies No management recom- ICCAT has recommended con- in the Gulf to assess the impact of mendations have been made No specific regulations servation actions for juveniles. the Deepwater Horizon Oil Spill. because of lack of data. in the Atlantic. THE NATURE CONSERVANCY | GULF OF MEXICO GULF OF MEXICO TUNA MIGRATIONS 4 THE NATURE CONSERVANCY | GULF OF MEXICO GULF OF MEXICO TUNA MIGRATIONS 5 Mapping Tuna Migrations Migratory Pathways and Connectivity Scope Bluefin Tuna Migratory Corridor Publicly available spatial data for tunas in the Gulf includes observations, tag-recapture, movement, and larvae dispersal data. A vast majority of the satellite telemetry data available for tunas follows blue- fin tuna. A kernel density analysis in ESRI ArcGIS (Geographic Information Sys- Observation data, or occurrence points, comes from a variety of sources. Re- tem) was used to generate a movement density map from 25 individual tuna search institutions and management organizations like NOAA periodically sur- tracklines in the Gulf that span over 9 years (April 2002 - July 2011). This map vey marine life aboard research vessels. Citizen science can provide valuable (Figure 2) represents the migratory corridor of bluefin tuna in the Gulf of Mex- observation information when recorded systematically. Fisheries catch data ico. The areas of high movement density constitute critical areas for threat can also be used