In areas of Alaska such as Tugidak Island, Prince William Sound, Glacier Bay, and Aialik Bay, populations of harbor seals (Phoca vitulina) have experienced population declines at concerning levels. Since 1998, the Alaska SeaLife Center (ASLC) has joined a national effort to better understand why these specific populations declined, and more importantly, determine how to aid in their overall recovery and survival.
Because harbor seals and Steller sea lions overlap in range, habitat, prey, and characteristics of the decline, leading hypotheses associated with the decline of harbor seals have been similar to those of Steller sea lions. Research associated with the harbor seal decline has been complementary to that of Steller sea lions, even though the actual cause(s) for their respective declines may or may not be identical. In 2000, the first Alaska Harbor Seal Research Plan was established to consolidate National Marine Fisheries Funded (NMFS) research on harbor seals—the ASLC was included in this plan in 2003 as congressional appropriations were awarded to the ASLC in 2002.
With our well equipped laboratory facilities and a captive population of trained harbor seals, research has mainly focused on harbor seal physiology as it relates to the overall health of the free-ranging population in Alaskan waters. During 2005-2006, the ASLC acquired eight female harbor seal pups from Prince William Sound—an area experiencing population declines—to participate in long-term studies that examine the relationship between diet and overall physiological health. To compliment the captive studies on-going at the ASLC, collaborative, multi-agency field studies involving ASLC resources have also been conducted in Aialik Bay, Prince William Sound, and Glacier Bay.
All ASLC harbor research projects conducted in the U.S. are federally permitted and undergo Institutional Animal Care and Use Committee (IACUC) reviews. The research categories that broadly encompass our harbor seal research include:
Captive Studies Lipids are essential building blocks for blubber development. Blubber and lipids maintain most marine mammals' abilities to thermoregulate (warm body in a cold ocean), promote growth, provide long-term engergy stores, and in the case of reproductive females, nurturing developing fetuses and nursing pups. Our researchers are investigating how changes in lipid (fat) composition and prey-specific protein composition affect the growth, maturation, reproduction, and overall health of eight harbor seal females.
FIELD STUDIES The Alaska Department of Fish and Game (ADF&G) and the ASLC have collaborated in sampling free-ranging harbor seals in Prince William Sound and Glacier Bay since 2003-2004. Animals are fitted with VHF transmitters that monitor their movements for up to 3-5 years. These devices are also designed to emit a signal when body temperatures drop below a pre-determined level indicating potential mortality. ASLC researchers are analyzing blood chemistries, gluconeogenic endrocrine levels, reproductive endocrine activity, and disease screening for all sampled animals.
Population Studies Researchers are using non-invasive, remote video monitoring equipment for long-term studies on behavior, movements, and mortality of harbor seals. Scientists have video recorded harbor seals at four different locations within Kenai Fjords and Aialik Bay. These cameras capture live, real-time video all of which is controlled with computer software at the main ASLC facility! This approach allows researchers to collect and record data on reproductive succes and monitor environmental and anthropogenic disturbances.
Environmental Monitoring Unique only to Alaska, harbor seals use glacial ice calveds from tidewater glaciers such as Aialik, Pederson, and Holgate glaciers to haul out to rest, give birth, nurse, and molt. In recent geological history, tidewater glaciers have been in the decline threatening seasonal harbor seal habitat. Using remote video monitoring equipment that can analyze glacial recession, and collecting site-specific oceanographic data, ASLC scientists have been monitoring environmental conditions at Aialik and Pederson glaciers.
EndocrinologY To maintain homeostasis, hormones must control growth, reproduction, and metabolism within the body. The system that regulates these hormones is called the endocrine system. ASLC scientists are investigating the role the endocrine system plays in harbor seal survival, and how contaminants affect this important regulatory system. In a partnership with the Alaska Native Harbor Seal Commission (ANHSC) and the ASLC, trained subsistence hunters collect data and tissue samples from harvested animals wherein ASLC scientists screen for diseases and analyze their reproductive success.