Ice Seal Research
Biological Monitoring

Examinations of helminth parasites in ice-associated seals

• The presence of helminth parasites (e.g., nematodes, including lungworms; cestodes; acanthocephalans; and trematodes) were documented in ringed, bearded, spotted, and ribbon seals.
• Walden, S. W., Bryan, A. B., McIntosh, A., Tuomi, P., Hoover-Miller, A., Stimmelmayr, R., and Quakenbush, L. 2020. Helminth fauna of ice seals in the Alaskan Bering and Chukchi seas, 2006–15. Journal of Wildlife Diseases 56(4): 863–872. doi: 10.7589/2019-09-228.

Algal toxins in Alaskan marine mammals

• Spatial patterns and prevalence of two of the most common harmful algal blooms, neurotoxins domoic acid (DA) and saxitoxin (STX), were documented in order to assess health risks to northern populations in Alaskan marine mammals were documented in order to assess health risks to northern populations including those species that are important to the nutritional, cultural, and economic well-being of Alaskan coastal communities.
• Lefebvre, K. A., L. Quakenbush, E. Frame, K. B. Huntington, G. Sheffield, R. Stimmelmayr, A. Bryan, P. Kendrick, H. Ziel, T. Goldstein, J. A. Snyder, T. Gelatt, F. Gulland, B. Dickerson, and V. Gill. 2016. Prevalence of algal toxins in Alaskan marine mammals foraging in a changing arctic and subarctic environment. Harmful Algae 55:13–24. doi: 10.1016/j.hal.2016.01.007.

Carbon sources and trophic relationships of ice seals during recent environmental shifts in the Bering Sea

• Do dramatic multiyear fluctuations in water temperature and seasonal sea ice extent and duration across the Bering–Chukchi continental shelf alter marine production processes linking primary producers to upper trophic-level predators? We compared the blubber fatty acid (FA) composition and stable carbon isotope ratios of individual FA (δ13CFA) of adult ringed seals (Pusa hispida), bearded seals (Erignathus barbatus), spotted seals (Phoca largha), and ribbon seals (Histriophoca fasciata), collectively known as “ice seals,” sampled during an anomalously warm, low sea ice period in 2002–2005 in the Bering Sea and a subsequent cold, high sea ice period in 2007–2010. Carbon derived from sea ice algae (sympagic production) relative to that derived from water column phytoplankton (pelagic production), contributes significantly to food webs supporting ice seals, and that the contribution is less in warm years with low sea ice than cold years with high sea ice. The FA composition of ice seals showed clear evidence of resource partitioning among ringed, bearded, and spotted seals, and little niche separation between spotted and ribbon seals, which is consistent with previous studies.
• Wang, S. W., A. M. Springer, S. M. Budge, L. Horstmann, L. T. Quakenbush, and M. J. Wooller. 2016. Carbon sources and trophic relationships of ice seals during recent environmental shifts in the Bering Sea. Ecological Applications 26:830–845.

Mercury and selenium concentrations in skeletal muscle, liver, and regions of the heart and kidney in bearded seals

• Mean concentrations of total mercury ([THg]) and selenium ([TSe]) (mass and molar-based) were determined for 5 regions of the heart and 2 regions of the kidney of bearded seals (Erignathus barbatus) harvested in Alaska, USA, in 2010 and 2011. Mean [THg] and [TSe] of bearded seal liver and skeletal muscle tissues were used for intertissular comparison. The Se:Hg molar ratios were used to investigate elemental associations and potential antioxidant protection against Hg toxicosis. Age was an important factor in [THg] and Se:Hg molar ratios in heart and kidney. Small but statistically significant differences in mean [THg] occurred among some of the 5 heart regions (p < 0.05). Mean [THg] was highest in liver, 3.057mg/g, and lowest in heart left ventricle, 0.017mg/g. Mean [THg] ranked: liver > kidney cortex > kidney medulla > skeletal muscle > heart left ventricle (p < 0.001). Mean [TSe] was highest in liver, 3.848mg/g, and lowest in heart left ventricle, 0.632mg/g. Mean [TSe] ranked: liver>kidney cortex>kidney medulla>skeletal muscle > heart left ventricle (p < 0.001). The Se:Hg molar ratios were significantly greater than 1.0 in all tissues (p < 0.001) and represented baselines for normal [TSe] under relatively low [THg]. Mean Se:Hg molar ratios ranked: heart left ventricle > kidney medulla > kidney cortex (p < 0.001).
• Correa, L., J.M. Castellini, L.T. Quakenbush, and T.M. O’Hara. 2015. Mercury and selenium concentrations in skeletal muscle, liver, and regions of the heart and kidney in bearded seals from Alaska, USA. Environmental Toxicology and Chemistry 34(10):2403–2408.

Historical comparisons of ringed and bearded seal diet, body condition, and productivity in the Bering and Chukchi seas.

• To determine whether recent decreases in sea ice have affected ringed and bearded seals in the Bering and Chukchi seas we compared diet, body condition, growth, productivity, and the proportion of pups harvested (an index of weaning success) during two periods; a historical (1975–1984) and a recent period (2003–2012). We also examined how changes in indices of seal health may be correlated with the reduction of sea ice characteristic of the recent period.
• Crawford, J. A., L. T. Quakenbush, and J. J. Citta. 2015. A comparison of ringed and bearded seal diet, condition and productivity between historical (1975–1984) and recent (2003–2012) periods in the Alaskan Bering and Chukchi seas. Progress in Oceanography 136:133–150. doi: 10.1016/j.pocean.2015.05.011.

Diet history of ice seals using stable isotope ratios in claw growth bands

• We examined the dietary history recorded in cornified claw sheaths of ringed seals (Pusa hispida) and bearded seals (Erignathus barbatus) to describe potential seasonal and interannual changes in their foraging. Seasonal layers of cornified cells deposited in claws can document trophic history up to about 10 years; thereafter, the claws start to wear at the distal end. A total of 38 claws were collected during Alaska Native subsistence harvests in 2008–2010 and seasonal growth bands were examined for stable nitrogen and carbon isotope ratios to assess long-term diet patterns. During 2007 (record ice minimum), proportionally more ringed seals fed at a lower trophic level. Bearded seals may have been foraging more pelagically from 2008 to 2010. Interannual variations and high variability between the two ice seal species and among individual diets illustrate the opportunistic nature and flexibility of ice seals to changes in prey.
• Carroll, S. S., L. Horstmann-Dehn, and B. L. Norcross. 2013. Diet history of ice seals using stable isotope ratios in claw growth bands. Canadian Journal of Zoology 91:191–202. doi: dx.doi.org/10.1139/cjz-2012-0137.

Trace element concentrations in bearded seals

• To determine if bearded seals (Erignathus barbatus) harvested near a zinc and lead mine (Red Dog, Alaska , USA) by subsistence hunters from Kivalina, Alaska, were as safe to eat as bearded seals from other locations in Alaska, we compared 19 trace element concentrations in liver tissue. Liver concentrations from nine bearded seals harvested near the Red Dog Mine (RDM) port site were compared with 15 bearded seals from two reference sites (Hooper Bay and Little Diomede, Alaska, USA). We found no evidence that bearded seals harvested near RDM were less safe to eat or that trace element concentrations were greater than those found in bearded seals harvested elsewhere in Alaska or Canada.
• Quakenbush, L., and J.J. Citta. 2009. Trace element concentrations in bearded seals (Erignathus barbatus) near Red Dog Mine compared to other locations in Alaska. Journal of Marine Biology, doi:10.115/2009/275040.

Perfluorinated contaminants in ice seals in Alaskan waters

• Perfluorinated contaminants (PFCs), such as perfluorooctane sulfonate (PFOS) and related synthetic compounds have been used as industrial and commercial surfactants and stain repellents for more than 50 years (Prevedouros et al., 2006). Liver samples were collected from the subsistence seal harvest from Alaskan coastal villages between 2003 and 2007.
• Quakenbush, L.T., and J.J. Citta. 2008. Perfluorinated contaminants in ringed, bearded, spotted, and ribbon seals from the Alaskan Bering and Chukchi Seas. Baseline/Marine Pollution Bulletin 56:1802–1814.

Polybrominated diphenyl ether compounds in ice seals from the Alaskan Bering Sea

• Polybrominated diphenyl ether compounds (PBDEs) are chemicals widely used as flame retardant additives in carpets and upholstery, and in plastics used in electrical appliances, televisions, and computers. Little is known about the toxicology of PBDEs. Blubber tissue from 20 seals was tested for 38 BDE congeners and 11 were detected. Concentrations detected in this study are not likely to cause any health problems for seals or the humans and polar bears that eat them.
• Quakenbush, L.T. 2007. Polybrominated diphenyl ether compounds in ringed, bearded, spotted, and ribbon seals from the Alaskan Bering Sea. Baseline/Marine Pollution Bulletin 54:226–246.

The Alaska Department of Fish and Game (ADF&G) has been monitoring the health and status of ice-associated seals (ringed, bearded, spotted and ribbon seals) in Alaska since 1960 by collecting information and samples from the Alaska Native subsistence harvest. This monitoring program is especially important because agencies have been unable to overcome the logistical and sampling constraints necessary to estimate seal abundance in remote, ice covered waters. As such, reliable estimates of abundance or population trends for ice seals are lacking. Retrospective data analyses from this monitoring program allow us to examine how parameters that affect population size and status may vary in time and how current conditions compare with past conditions. Parameters we monitor that are indicative of population health or status include growth rate, body condition, diet, age distribution, sex ratio, age of maturation, and pregnancy rate. Since 2000, ADF&G has also conducted surveys for local knowledge and hunter preferences and analyzed tissue samples for contaminants and disease. All of these collections rely on the cooperation of coastal subsistence communities. Villages that have participated in the sampling program span the region from Hooper Bay in the Bering Sea to Kaktovik in the Beaufort Sea, including islands in the Bering Sea.

Biological monitoring of ringed seals in the Bering and Chukchi seas

• In Alaska, the subsistence harvest of marine mammals, including ice seals, has provided important information regarding population status and health since the 1960s. Decreasing sea ice is expected to affect ice seal populations by reducing the amount and time that sea ice is available for resting, pupping, pup rearing, and molting. This project continues the long-term sampling of the subsistence harvest to monitor parameters related to ringed seal population status and health in the Bering and Chukchi seas. Although listed as threatened under the Endangered Species Act in 2012, no recovery plan or recovery objectives have been developed for ringed seals. The purpose of this project was to address critical data gaps in understanding how ringed seals are responding to changes in sea ice, infectious diseases, and contaminants, and how quickly these changes could alter population dynamics.
• Quakenbush, L. T., A. Bryan, J. Crawford, J. Olnes. 2020. Biological monitoring of ringed seals in the Bering and Chukchi seas. Final Report to National Oceanographic and Atmospheric Association, Award Number: NA16NMF4720079. 33 pp + appendices.
• Report (PDF 480 kB)

Biological monitoring of ice seals in Alaska to determine health and status of populations—diet, disease, contaminants, reproduction, body condition, growth, and age at maturity.

• Bearded (Erignathus barbatus), spotted (Phoca largha), ribbon (Histriophoca fasciata), and ringed (Pusa hispida) seals are the species of Alaska’s seals collectively called ice seals because of their association with sea ice and their dependence on it for resting, pupping, and molting. Ice seals are important components of the ecosystems of the Bering, Chukchi, and Beaufort seas and they are important to the subsistence-based culture of Alaska Natives for food and raw materials. In Alaska, the subsistence harvest of marine mammals, including ice seals, has provided important information regarding population status and health since the 1960s. Decreasing sea ice is expected to affect ice seal populations by reducing the amount and time that sea ice is available for resting, pupping, pup rearing, and molting. This project continues the long-term sampling of the subsistence harvest to monitor parameters related to ice seal population status and health in the Bering and Chukchi seas. This project sampled bearded, spotted, and ribbon seals only; ringed seals were sampled and reported under a concurrent NOAA Species Recovery Grant (Award No. NA16NMF4720079). The purpose of this project was to address critical data gaps in understanding how seals are responding to changes in sea ice, infectious diseases, and contaminants and how quickly these changes could alter population dynamics.
• Quakenbush, L. 2020. Biological monitoring of ice seals in Alaska to determine health and status of populations—diet, disease, contaminants, reproduction, body condition, growth, and age at maturity. Final Report to National Oceanographic and Atmospheric Association, Award Number: NA16NMF4390029. 47 pp + appendices.
• Report (PDF 33,603 kB)

Biology of Ice Seals, reports presented to NOAA

• The Alaska Department of Fish and Game (ADF&G) has been monitoring the health and status of bearded seals (Erignathus barbatus), ribbon (Histriophoca fasciata), ringed (Pusa hispida), and spotted (Phoca largha) seals in Alaska since 1962 by collecting information and samples from the Alaska Native subsistence harvest. This monitoring program is especially important because agencies have yet to overcome the logistical constraints necessary to estimate seal abundance in remote, ice covered waters. As such, reliable estimates of bearded seal abundance or population trend are lacking. Retrospective analyses of data provided by this monitoring program allow us to examine how parameters that affect population size may vary in time and how current conditions compare with past conditions. Parameters we monitor that are indicative of population health or status include growth rate, body condition, diet, age distribution, sex ratio, age of maturation, and pregnancy rate. Since 2000, ADF&G has also conducted surveys for local knowledge and hunter preferences and analyzed tissue samples for contaminants and disease. All of these collections rely on the cooperation of coastal subsistence communities. Villages that have participated in the sampling program span the region from Hooper Bay in the Bering Sea to Kaktovik in the Beaufort Sea, including islands in the Bering Sea; an area that encompasses most of the range these ice seals in Alaska.

• Biology of the Bearded Seal

  • Quakenbush, L. T., J. J. Citta, and J. A. Crawford. 2011. Biology of the bearded seal (Erignathus barbatus) in Alaska, 1961-2009. Alaska Department of Fish and Game, Unpublished report to NMFS. 71 pp.
  • Report (PDF 1,216 kB)

  Biology of the Ribbon Seal

  • Quakenbush, L. T., and J. J. Citta. 2008. Biology of the ribbon seal in Alaska. Alaska Department of Fish and Game, Unpublished report to NMFS. 45 p.
  • Report (PDF 307 kB)

  Biology of the Ringed Seal

  • Quakenbush, L. T., J. J. Citta, and J. A. Crawford. 2011. Biology of the ringed seal (Phoca hispida) in Alaska, 1960-2010. Alaska Department of Fish and Game, Unpublished report to NMFS. 66 pp.
  • Report (PDF 1,260 kB)

  Biology of the Spotted Seal

  • Quakenbush, L. T., J. J. Citta, and J. A. Crawford. 2009. Biology of the spotted seal (Phoca largha) in Alaska from 1962 of 2008. Alaska Department of Fish and Game, Unpublished report to NMFS. 66 p.
  • Report (PDF 858 kB)

2021

• Bryan, A., J. A. Crawford, L. T. Quakenbush, J. Olnes, and R. Adam. 2021. Status of ringed, bearded, spotted, and ribbon seals in Alaska using harvest-based monitoring by decade: 1960s, 1970s, 2000s, and 2010s. Alaska Marine Science Symposium. 26-28 January. Anchorage, Alaska, USA.
  (Abstract) (PDF 35 kB) (Poster) (PDF 1,916 kB)

2020

• Adam, R., A. Bryan, L. Quakenbush, J. Crawford, and L. Biderman. 2020. Age structure of subsistence harvested ice seals in Alaska 2000–2018. Alaska Marine Science Symposium. 27–31 January. Anchorage, Alaska, USA. (Abstract and poster) (PDF 821 kB)
• Biderman, L., A. Bryan, J. Crawford, J. Citta and L. Quakenbush. 2020. Occurrence of Arctic and saffron cod in the diet of ringed seals at Shishmaref, 1975–2018. Alaska Marine Science Symposium. 27–31 January. Anchorage, Alaska, USA. (Abstract and poster) (PDF 439 kB)
• Bryan, A.L., H.S. Walden, A. McIntosh, P. Tuomi, A. Hoover-Miller, R. Stimmelmayr, and L.T. Quakenbush. 2020. Helminth fauna of ice seals in the Alaskan Bering and Chukchi Seas, 2006–2015. Alaska Marine Science Symposium, 27–30 January, Anchorage AK. (Abstract and poster) (PDF 334 kB)

2019

• Adam, R., A. Bryan, L. T. Quakenbush, J. A. Crawford and L. Biderman. 2019. Bearded seal productivity in Alaska using harvest-based monitoring, 1975–2016. Alaska Marine Science Symposium. 28–31 January. Anchorage, Alaska, USA. (Abstract and poster) (PDF 240 kB)
• Biderman, L., A. Bryan, J. A. Crawford, J. J. Citta and L. T. Quakenbush. 2019. Occurrence of Arctic cod and saffron cod in the diet of ringed seals, 1975–2016. Alaska Marine Science Symposium. 28–31 January. Anchorage, Alaska, USA. (Abstract and poster) (PDF 127 kB)
• Bryan, A., L. T. Quakenbush, J. A. Crawford, L. Biderman and R. Adam. 2019. Ringed seal productivity in Alaska using harvest-based monitoring, 1975–2016. Alaska Marine Science Symposium. 28–31 January. Anchorage, Alaska, USA. (Abstract and poster) (PDF 578 kB)
• Bryan, A., L. Quakenbush, J. Crawford, L. Biderman, and R. Adam. 2019. Ringed, bearded, and spotted seal productivity in Alaska using harvest-based monitoring, 1960s–1980s and 2000–2018. World Marine Mammal Conference. 9–12 December, Barcelona, Spain. (Abstract and poster) (PDF 384 kB)

2018

• Bryan, A., L. T. Quakenbush, J. A. Crawford, L. Biderman and R. Adam. 2018. Spotted seal productivity in Alaska using harvest-based monitoring; 1960s, 1970s, and 2000s. Alaska Marine Science Symposium. 22–26 January. Anchorage, Alaska, USA. (Abstract and poster) (PDF 532 kB)

2017

• Bryan, A., L. Quakenbush, J. Crawford. 2017. Ringed seal productivity in Alaska using harvest-based monitoring, 1975–2015. 22nd Biennial Conference on the Biology of Marine Mammals. 22–27 October 2017, Halifax, Nova Scotia, Canada. (Abstract and poster) (PDF 679 kB)

2016

• Quakenbush, L., J. A. Crawford, and J. J. Citta. 2016. Updated status of ringed and bearded seal productivity in Alaska using harvest-based monitoring results for 2013 and 2014. Alaska Marine Science Symposium, 25–29 January, Anchorage, AK. (Abstract and poster) (PDF 1,070 kB)

2015

• Bryan, A., L. Quakenbush, L. Horstmann-Dehn. What do bearded seals really eat– A methods comparison. Alaska Marine Science Symposium, Anchorage, Alaska, 19–23 January 2015. (Abstract and poster) (PDF 42 kB)

2013

• Bryan, A., J. A. López, L. Horstmann-Dehn, and L. Quakenbush. 2013. Fish species identified in bearded seal diet using stomach contents and fecal DNA. Alaska Marine Science Symposium, 21–25 January, Anchorage, AK. (Abstract and poster) (PDF 7,310 kB)
• Crawford, J., L. Quakenbush, and J.J Citta. 2013. Ringed seals and climate change: current status of ringed seals in Alaska. 20th Biennial Conference on the Biology of Marine Mammals, 9–13 December, Dunedin, New Zealand. (Abstract and presentation) (PDF 233 kB)
• Crawford, J. and L. Quakenbush. 2013. Ringed seals and climate change: early predictions versus recent observations in Alaska. 28th Lowell Wakefield Fisheries Symposium, Responses of Arctic marine ecosystems to climate change, 26–29 March 2013, Anchorage, AK. (Abstract and presentation) (PDF 60 kB)

2012

• Bryan, A., L. Quakenbush, and L. Horstmann-Dehn. 2012. How well do stable isotopes represent bearded seal diet? Alaska Marine Science Symposium, 16–20 January, Anchorage AK. (Abstract and poster) (PDF 654 kB)
• Quakenbush, L., J. J. Citta, and J. A. Crawford. 2012. Ringed and bearded seal populations in Alaska are not showing signs of decline. Alaska Marine Science Symposium, 16–20 January, Anchorage, AK. (Abstract and poster) (PDF 10 kB)

2011

• Bryan, A., L. Horstmann-Dehn, and L. Quakenbush. 2011. Do stomach contents, fatty acids and stable isotopes yield the same results? 19th Biennial Conference on the Biology of Marine Mammals, November 27–December 2, Tampa, FL. (Abstract and poster) (PDF 386 kB)
• Bryan, A. L., L. Quakenbush, and L. Dehn. 2011. Comparison of three diet analysis methods within individual bearded seals. Alaska Marine Science Symposium, 17–21 January, Anchorage, AK. (Abstract and poster) (PDF 275 kB)
• Crawford, J. and L. Quakenbush. 2011. Stomach content analysis reveals temporal changes of ice seal diets in Alaska: Climate change or regime shift? Alaska Marine Science Symposium, 17–21 January, Anchorage, AK. (Abstract and poster) (PDF 683 kB)

2010

• Crawford, J., L. Quakenbush, and J. Citta. 2010. Stomach content analysis reveals temporal changes in spotted seal (Phoca largha) diet composition in Alaska, 1966-2008. Alaska Marine Science Symposium, 18–22 January, Anchorage, AK. (Abstract and poster) (PDF 14 kB)

Posters presented in communities to present results from seal sampling.

Biomonitoring update to the community of Shishmaref. 2014. Arctic Marine Mammal Program, ADFG.
Report (PDF 709 kB)

Biomonitoring update presented to all contributing communities. 2013. Arctic Marine Mammal Program, ADFG.
Report (PDF 709 kB)

Biomonitoring update to the community of Shishmaref. 2011. Arctic Marine Mammal Program, ADFG.
Report (PDF 709 kB)

Biomonitoring update to the community of Hooper Bay. 2009. Arctic Marine Mammal Program, ADFG.
Report (PDF 709 kB)