In the year 2000, a ‘decade of discovery’ of the marine world began. A total of 2,700 scientists, 80+ nations, 540 expeditions and $650 million (US) collectively made up what is known as the Census of Marine Life. This census was comprised of 17 main projects and 7 affiliated projects, that produced 2,600+ publications, described 6,000+ new species and 30 million species distribution records and counting. Information regarding sharks can be found in many of these projects; however, sharks were a major focus in the Tagging of Pacific Predators research program – TOPP.
Researchers from Canada, the U.S., Australia, Mexico, France, the UK, and Japan joined forces to create TOPP, which set out to study the migration of marine fishes, reptiles, birds, cetaceans and cephalopods throughout the North Pacific Ocean. TOPP provided valuable information on the ecological functions of the Pacific Ocean, including feeding and breeding hot spots, in addition to migration pathways.
Picture 1: Salmon sharks annually patrol Pacific waters from California to Alaska. Photo Credit: NOAA
Scientists involved in TOPP used ARGOS satellite tags and pop-up satellite archival tags (PSATs) (see photo below) to study the migration of most Pacific sharks. These devices are attached to the animals externally. Once these devices reach the surface the information is sent to the ARGOS satellite. Satellite tags are permanently attached to the dorsal fin of the shark (unless removed by researchers), and transmit information to the satellite when the dorsal fin breaches the surface. In contrast, PSATs are temporarily attached to the shark. After a given period of time, the tag pops off and floats to the surface where the signal is then sent to the satellite. PSATs and satellite tags were used to monitor the movements of salmon sharks (Lamna ditropis), blue sharks (Prionace glauca), thresher sharks (Alopias vulpinus), shortfin mako sharks (Isurus oxyrinchus), and great white sharks (Charcharodon carcharias).
Picture 2: PSATs getting ready for deployment. Photo Credit: WikiCommons
The Tagging of Pacific Predators project logged more than 50,000 tracking days of Pacific shark migration. They have identified a region off the southern coast of California known as the California Current System (CCS) as a seasonal, ecological hot spot used by all sharks. The CCS extends from San Diego north to San Luis Obispo and westward over 500 km. The great white shark migrates back and forth from the CCS to the oligotrophic regions of the central Pacific. The migration patterns of mako, blue and thresher sharks overlap, as all three use the CCS throughout the North American continental shelf. Finally, the salmon shark migrates the greatest distance, moving between the CCS and the cold northern waters of Alaska. Research to further understand Pacific shark migration continues to this today.
Picture 3: Sharks’ continuously migrate across boarders. Therefore, we must conserve them as though we are a borderless world. Photo Credit: Ktrinko
The Tagging of Pacific Predators was a massive undertaking and collaboration of scientists from all around the world that tagged and tracked marine animals in the Pacific Ocean. The program developed modern technologies to study sharks, as well as recognized migration patterns of top predators in the North Pacific Ocean. TOPP demonstrates that sharks, and most other pelagic predators, migrate past country borders. This proves that countries need to collaborate and manage these animals on a global scale. Without this, the mismanagement of just a few countries could lead to the collapse of several shark populations. Furthermore, TOPP has recognized breeding and feeding hot spots throughout the Pacific Ocean, such as the CCS. Protection of these areas from heavy fishing, and the effects of extraction of natural resources is essential to the conservation of sharks.
All of the information for this blog is from the book titled, “Life in the World’s Oceans: Diversity, Distribution and Abundance”, edited by Alasdair D. McIntyre (2009).
Written by: Scott Seamone, ShARCC Intern