# The challenging process of tagging giant sharks How scientists struggle to track the world's largest fish - **Source:** [Popular Science](https://brifing.si/source/cc3d313a-759c-4802-b881-fc8585f35ef9) - **Published:** 2026-08-28 - **Topic:** [Business](https://brifing.si/c/business) - **Original article:** - **On Brifing:** https://brifing.si/s/17a48a9b-9675-4b60-bc00-712857c9e4a2 ## Close encounter with giants PhD candidate Jaida Elcock from MIT and Woods Hole Oceanographic Institution studies the movement patterns of whale sharks and basking sharks, the two largest fish species. She tags adult whale sharks in plankton-rich waters about 100 miles off New England. These gentle giants can reach 60 feet in length and cannot be caught by traditional fishing methods as they are filter feeders. ## The tagging challenge The process begins with spotter planes locating the sharks. Then a two-person team enters the water: one documents the shark's unique spot patterns while the other attaches a tag to the dorsal fin that records water temperature, diving depth, and movement patterns. Elcock describes the tag as 'like a big bobby pin you have to pry open and clip onto the fin.' The tags eventually detach and float to the surface with collected data. ## Rare adult population While juvenile whale sharks are commonly seen in tropical waters like the Philippines and Mexico, the Northwest Atlantic hosts reproductively mature adults - a rare find since only about 25% of the adult population has been documented. Elcock's team is analyzing last year's tagging data to understand why these giants gather in this specific region and their behavioral patterns. ## Filter feeding mechanism Unlike predatory sharks, whale sharks are filter feeders, straining up to 6,000 liters of water per hour for plankton. This makes traditional baiting methods ineffective for tagging. Though they appear to swim slowly, they can actually outpace human swimmers easily. Their massive size and feeding behavior present unique challenges for researchers attempting to study them. ## Equipment and endurance test The tagging team must free dive (without scuba gear) to reach these giants. Elcock notes, 'Even with the best fins, you need tremendous endurance. It's like holding your breath after sprinting.' Having grown up in the desert, she finds working in the vast open ocean still feels surreal. The team also occasionally encounters other species like hammerheads during tagging operations. ## Data collection technology The sophisticated tags record critical data including surface time, dive depth, and water temperature. After a predetermined period, the tags detach automatically and float to the surface. Their built-in radio transmitters help the team retrieve them. This data helps scientists understand how climate change might be affecting the migration patterns of these massive creatures. ## Ocean health indicators Whale sharks serve as important indicators of ocean health. Changes in plankton density and ocean currents directly affect their behavior. By analyzing this data, scientists develop conservation strategies for the species while gaining insights into broader marine ecosystem changes. Their presence in specific areas often signals rich biodiversity beneath the waves. ## Pushing scientific boundaries Elcock's research is expanding our understanding of marine biology. Documenting the migration routes of rarely seen adult whale sharks is crucial for their conservation. Solving the mystery of why they aggregate in the Northwest Atlantic could provide keys to understanding larger shifts in ocean ecosystems and help protect these magnificent creatures for future generations. ## Sources covering this story - https://www.popsci.com/environment/tagging-whale-sharks-video/ — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._