Background:
Human-made noise in the ocean can impact marine mammals, which rely on sound for communication, navigation, and survival. While most research has focused on whales and dolphins due to their sensitivity to sonar, less is known about how noise affects seals and sea lions (pinnipeds). The Northern Channel Islands, home to six pinniped species, provide a key location to study this issue, as the region overlaps with naval sonar exercises. California sea lions are particularly at risk because they spend more time in coastal areas where noise disturbances are frequent. Research using tracking data shows that, unlike elephant seals, which forage far offshore and are less affected, sea lions are often exposed to underwater noise, potentially impacting their ability to find food and raise their young. Understanding these effects is crucial for protecting marine life in noise-heavy environments.
Yacht owners, vessel operators, and charter agencies can play a vital role in advancing this research by supporting tracking and data collection efforts in these key regions.
Mission:
This project aims to determine whether Navy sonar affects the behavior of California sea lions at sea and whether such disturbances could impact their populations. To gather this important data, researchers will attach behavioral and acoustic tracking tags to female sea lions on San Nicolas Island, a major breeding site, and monitor their foraging trips, many of which overlap with naval activity zones. Private vessels, including those owned by yachties, boat enthusiasts, ocean conservationists, captains, and crew members, can serve as invaluable platforms for this research, supporting scientists by providing access to key foraging areas and helping collect data during the study. By observing sea lion responses to controlled sonar exposure—both immediately and over time—researchers can assess whether noise disruptions hinder their ability to find food. Since female sea lions must return regularly to nurse their pups, longer foraging trips due to sonar interference could indicate difficulties in gathering enough food. The involvement of private vessels in this research will allow for more comprehensive data collection, contributing to the study’s goal of understanding how underwater noise affects sea lion populations and helping shape effective conservation strategies.
Research Impacts & Applications:
The information gained from this project will be used to inform the Navy's environmental impact assessments when determining how military activity influences marine mammal behavior in the southern California offshore range. There will also be two post-doctoral scholars working on analyzing the animal movement data and the population-level implications of the results. All data-sharing agreements will be managed by the University of California Santa Cruz.
By participating in this research, yacht owners, boaters, ocean enthusiasts, captains, and crew members will contribute directly to the collection of critical data on sea lion behavior, helping to advance scientific understanding of the impact of sonar and other ocean noise on marine life.
Program Partners:
Relevant Scientific Publications:
- Costa, D. P. 2012. A Bioenergetics Approach to Developing the PCAD Model. Pages 423-426 in A. N. Popper and A. Hawkins, editors. The Effects of Noise on Aquatic Life. Advances in Experimental Medicine and Biology Springer Science+Business Media.
- Costa, D. P., G. P. Antonellis, and R. De Long. 1991. Effects of El Niño on the foraging energetics of the California sea lion. Pages 157-165 in F. Trillmich and K. A. Ono, editors. Effects of El Niño on Pinnipeds. Springer Verlag:, Berlin.
- Costa, D. P., L. Schwarz, P. Robinson, R. S. Schick, P. A. Morris, R. Condit, D. E. Crocker, and A. M. Kilpatrick. 2016. A Bioenergetics Approach to Understanding the Population Consequences of Disturbance: Elephant Seals as a Model System. Pages 161-169 in A. N. Popper and A. Hawkins, editors. Effects of Noise on Aquatic Life II.
- Costa, D. P., D. E. Crocker, J. Gedamke, P. M. Webb, D. S. Houser, S. B. Blackwell, D. Waples, S. A. Hayes, and B. J. Le Boeuf. 2003. The effect of a low-frequency sound source (acoustic thermometry of the ocean climate) on the diving behavior of juvenile northern elephant seals, Mirounga angustirostris. J Acoust Soc Am 113:1155-1165.
- Durban, J. W., B. L. Southall, J. Calambokidis, C. Casey, H. Fearnbach, T. W. Joyce, J. A. Fahlbusch, M. G. Oudejans, S. Fregosi, A. S. Friedlaender, N. M. Kellar, and F. Visser. 2022. Integrating remote sensing methods during controlled exposure experiments to quantify group responses of dolphins to navy sonar. Marine Pollution Bulletin 174:113194.
- Keen, K. A., R. S. Beltran, E. Pirotta, and D. P. Costa. 2021. Emerging themes in Population Consequences of Disturbance models. Proc Biol Sci 288:20210325.
- Kastak, D., R. J. Schusterman, B. L. Southall, and C. J. Reichmuth. 1999. Underwater temporary threshold shift induced by octave-band noise in three species of pinniped. J Acoust Soc Am 106:1142-1148.
- Kuhn, C. E., and D. P. Costa. 2014. Interannual variation in the at‐sea behavior of California sea lions (Zalophus californianus). Marine Mammal Science 30:1297-1319.
- McHuron, E. A., M. Mangel, L. K. Schwarz, and D. P. Costa. 2017. Energy and prey requirements of California sea lions under variable environmental conditions. Marine Ecology Progress Series 567:235-247.
- McHuron, E. A., D. P. Costa, L. Schwarz, M. Mangel, and J. Matthiopoulos. 2016. State‐dependent behavioural theory for assessing the fitness consequences of anthropogenic disturbance on capital and income breeders. Methods in Ecology and Evolution 8:552-560.
- Southall, B. L., J. J. Finneran, C. Reichmuth, P. E. Nachtigall, D. R. Ketten, A. E. Bowles, W. T. Ellison, D. P. Nowacek, and P. L. Tyack. 2019. Marine Mammal Noise Exposure Criteria: Updated Scientific Recommendations for Residual Hearing Effects. Aquatic Mammals 45:125-232.
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