AFSC Internships, 2007 Intern Experiences - Gretchen Thuesen
Gretchen Thuesen with a northern fur seal pup |
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Gretchen Thuesen, a senior at the University of Washington majoring in aquatic and fishery sciences, relates her 2007 summer internship on San Miguel Island, CA.
This summer, I was given the opportunity to participate in an internship that resulted in an unforgettable experience. For two months, I studied both California sea lions (Zalophus californianus) and northern fur seals (Callorhinus ursinus) on San Miguel Island, which is one of the eight Channel Islands located off of the southern coast of California. San Miguel Island is the westernmost of the chain and is thus the most exposed to the elements, receiving northwesterly winds and severe weather, including fog, from the open ocean. The cold, nutrient-rich water surrounding the island supports an array of marine life, including various species of seabirds, fish, invertebrates, and pinnipeds.
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View of Adam's Cove from one of the stationary blinds on San Miguel Island.
A Curious California sea lion pup came to say hi while we were doing our first dead pup count. |
San Miguel Island is home to one of the largest pinniped aggregations in the world. Throughout the year, four pinniped species use the island as breeding grounds: California sea lions (Zalophus californianus), northern fur seals (Callorhinus ursinus), northern elephant seals (Mirounga angustirostris), and harbor seals (Phoca vitulina). Of these four species, Zalophus and Callorhinus breed and pup on the island during the summer months. During my two-month stay on San Miguel, I participated in several projects in which data was collected on both species and incorporated into master databases that have been ongoing for twenty years.
Sea lion research on San Miguel Island has been ongoing for over three decades. Over the years, the California Sea Lion Demographic Assessment Program was developed, which is responsible for monitoring and observing the sea lion population on San Miguel. Within this program, a long-term branding program arose and has been ongoing for twenty years.
While on the island, we resighted branded Zalophus individuals from mid-May through early-August to determine survival and birth rates. Intensive resighting occurred from mid-May through the end of June. This is when pupping occurs, so we focused on resighting branded cows with pups. July is breeding season, so we focused on resighting branded territorial and idle bulls. Because sea lions haul out all over the island, we hiked to several different locations on a regular basis to look for branded individuals. I quickly discovered that resighting requires stamina and patience: we would resight for hours at a time while enduring harsh weather conditions including strong winds and fog. We also conducted live and dead pup counts in order to determine production and pup mortality rates. Additionally, we collected teeth to determine the ages of sea lion carcasses as well as collecting scat to determine foraging ecology.
Northern fur seal research on San Miguel Island began in 1969 with the establishment of a research program designed to study the demography of the population. Shortly thereafter, in 1975, the annual tagging program began. Analogous to the California Sea Lion Demographic Assessment Program, the goals of the tagging program are to monitor population trends and to estimate age-specific survival and reproductive rates. As with sea lions, we resighted tagged individuals and conducted live and dead pup counts. Data collected in the field was then brought back to the office in Seattle and analyzed. While in the office, I was able to manipulate the data we had collected. The information collected on San Miguel Island has provided valuable information over the years on the life history of both California sea lions and northern fur seals.
Resighting branded California sea lion individuals in West Cove. We were each equipped with a scope and PDA when resighting.
Reading northern fur seal tags in the mobile blind. |
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By being isolated on San Miguel Island for two months, I was able to test my ability to work in the field for extended periods of time and to determine whether field work was something I enjoyed. While in the field, I was exposed to various methods of data collection and was given the opportunity to participate in several projects that increased my exposure to the various possibilities of field work. Additionally, I was given the opportunity to work with several great researchers, who were each very enthusiastic about the projects we were doing. They were constantly answering all of my questions and providing endless information on each project as we worked side by side. In addition, they made sure I was a part of each and every project that was carried out on the island so that I would obtain a well-rounded and all-encompassing experience in the field. I could not have asked for a better group to work with. They were great!
When we returned from San Miguel Island, I was given the chance to work with and manipulate the data we had collected in the field. It was exciting to have gone through the process of collecting data in the field, then determine what these data tell us about this year as well as how these data contribute to previous research. By going through this entire process of data collection and manipulation, I was able to observe and apply techniques I have learned in the classroom. This internship gave me great exposure to valuable field techniques and allowed me to sharpen my data analysis skills; both of which will be extremely useful in future research and career endeavors.
Studying California sea lions on San Miguel Island was an amazing experience I will never forget.
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