UnearthingInsights on Climate Change through Salmon Sharks' Behavior
Over the past two decades, ocean data collection has experienced a significant surge, thanks primarily to the deployment of Argo floats that now monitor global ocean temperatures and salinity levels. Despite this progress, gaps remain, particularly in remote areas like polar and coastal regions. To overcome these data shortcomings, scientists are turning to marine life for assistance.
Elephant seals, equipped with temperature, salinity, and depth sensors, have been instrumental in filling these observational gaps in challenging ocean environments. Researchers began using this method in 2002, transforming our comprehension of ocean currents, sea ice formation, and submesoscale processes—minutely important ocean movements impacting larger climate patterns. Now, scientists are expanding this concept to sharks, specifically salmon sharks (Lamna ditropis).
These large, non-air-breathing marine animals are tagged with satellite transmitters, recording depth, temperature, and movement data. Tracking sharks is particularly advantageous due to their deep-diving capabilities and extensive travel distances, making it easier to collect oceanographic data in poorly explored regions. In 2015, a 5-foot-long salmon shark tagged off the coast of Port Gravina, Alaska, provided invaluable information during the infamous Blob event—a massive warm water anomaly that lasted for nearly three years, causing disruptions to marine ecosystems.
The CTD-SRDL tag attached to this shark allowed researchers to track its temperature and salinity profiles while documenting its natural movements. Over a 36-day period, the shark covered more than 840 miles, relaying over 56 detailed temperature-salinity profiles via satellite. The data revealed that the shark primarily swam through warm water, with over 75% of readings showing above-average temperatures. Interestingly, the saltiness of the water was more variable throughout the shark's journey.
The most intriguing discovery was the shark's interactions with mesoscale eddies—large rotating bodies of water influencing ocean circulation and heat distribution. Over its adventure, the shark encountered seven such eddies, capturing data on their temperature and salinity structures. These observations can help scientists better understand how heat and salinity move through the ocean, impacting larger climate patterns.
Comparing the tagged shark's data to that of Argo floats in the same region revealed several advantages. The shark's data had a higher resolution, especially in dynamic areas influenced by eddies and coastline interactions. If tagged sharks could provide a similar number of high-resolution profiles in the Gulf of Alaska, the result would be a much clearer picture of ocean conditions.
Although the concept of "employing" sharks as oceanographers is in its infancy, its potential is immense. By leveraging the animals' natural abilities to navigate and explore, researchers can gather data from areas that traditional instruments cannot reach. As technology advances and tagging efforts are refined, researchers hope to integrate shark-collected data into global ocean monitoring systems, complementing existing tools like Argo floats.
Understanding ocean variability is instrumental for forecasting climate change, managing fisheries, and preserving marine ecosystems. By embracing the help provided by marine species, such as elephant seals and salmon sharks, we might soon learn more about ocean dynamics, leading to more accurate models and predictions.
Enrichment Data:
- Data Collection in Remote Areas:
- Tagging elephant seals and salmon sharks allows scientists to gather data in remote ocean areas that are challenging to access with conventional instruments. These marine animals can dive to considerable depths, travel long distances, and traverse harsh environments, providing valuable insights into deep-sea environments and ocean currents in the Gulf of Alaska.
- Submesoscale Processes:
- The movements and behaviors of elephant seals and salmon sharks contribute to a better understanding of submesoscale processes in the Gulf of Alaska. These processes, which influence ocean dynamics, involve small-scale ocean features, such as eddies, that significantly impact larger-scale circulation patterns.
- Sea Ice Formation:
- The data collected from marine animals in the Gulf of Alaska can provide insights into sea ice formation and its dynamics, as well as how sea ice affects ocean currents and overall marine ecosystem health.
- Ocean Currents:
- Collecting temperature, salinity, and depth data from marine animals like elephant seals and salmon sharks can help researchers model and predict ocean currents more accurately, especially in regions with limited observational data.
- Integration with Other Data:
- Combining data from marine animals with other observational and modeling data can provide a more comprehensive understanding of ocean dynamics, contributing to more accurate predictions and leading to better management of marine resources.
- The deployment of satellite transmitters on salmon sharks could help fill data gaps in shark behavior and oceanographic patterns in poorly explored regions, similar to how elephant seals have aided in understanding submesoscale processes.
- Analysing the fossil records of prehistoric sharks could provide valuable insights into how climate change has impacted shark populations and their oceanic habitats over millions of years.
- As predators, sharks play a crucial role in maintaining the balance of marine ecosystems, and understanding their movements and behaviors could help conserve other wildlife in the ocean.
- In the image 'dnl_0386_alaska_portfidalgo_salmonshark_byjenniferidol_0', a salmon shark can be seen swimming in the ocean, contributing to the collection of temperature and salinity data.
- The Blob event, a massive warm water anomaly in 2015, was an opportunity for researchers to collect and analyze data from tagged salmon sharks, providing insights into how climate change affects marine ecosystems.
- With advancements in technology and refinement of tagging techniques, scientists aim to integrate shark-collected data into global ocean monitoring systems, enhancing our understanding of ocean dynamics and climate change.
- According to the Oceanographic Society, conserving shark populations and their habitats is essential for maintaining healthy oceans, as they play a vital role in maintaining the balance of marine ecosystems and providing economic benefits to coastal communities.
