Alaska Northern Fur Seals

Most northern fur seals inhabit the Pribilof Islands, in Alaska. These remote islands are off the coast of mainland Alaska, in the Bering Sea. Organisms there are largely influenced by the ocean circulation which varies with trade winds. In addition, the extremely remote distance between the islands and the mainlands makes the Pribilof Islands more vulnerable. (Danielson,2012)

• Stronger currents 
• More frequent storms 

•  Climate change: The climate change-induced strong winds process obstacles to fur seals' migration routes, especially for the seals' pups.
• The sea surface temperature(SST)-sea ice concentration(SIC) studies show that the positive relationship between SST and wind speed in sea ice dominated areas and a negative correlation over open water condition. The presence of sea ice would indicate a correlation between SST and wind speed(Zhang,2018).  The vast thermal difference between open water and sea ice increase the temperature gradients, largely disrupt the atmosphere stability (Zhang,2018).

In Alaska, the negative relationship between surface winds and SST and the present of SIC trigger abnormal wind flows, making wind strength unstable. 

• Sea ice loss
• Loss of habitat
• Nutritient deficiencies 

- In Alaska, the climate changes related to sea ice retreat leads to direct impacts on coastal mammals and human beings. Warmer temperature induces the loss of sea ice, lead to acidification, and reduces economic productivity (Huntington, 2015). Sea ice presence is much shorter than before. representing a loss of habitat for nursing the pup seals (Burn, 1970). 

- Stronger predator threats

For fur seals and polar bears, which mostly rely on the sea ice, the warmer weather leads to sea ice melting and population decreases. The loss of sea ices benefits certain species, which are more adept to fewer sea ices conditions, like killer whales. Without the sea ices as shelter, it is easier for predators to spot their prey (Moore and Huntintong, 2008). Climate changes make fur seals' living condition more adverse and create a better condition for their predators. The cumulative impacts on habitat loss far fur seals and greater forces for predators strongly decrease seals' population, induce more injuries and deaths, 

•  El Niño is a kind of weather pattern, which most disturbed the normal weather phenomenon. On the one hand, El Niño would promote global warming, but on the other hand, global warming will strengthen the influences of El Niño (CHO, 2016). ENSO oscillation is a pattern of pressure, temperature and rainfall fluctuation that can have a global climate impact.

• It accounts for one-third of the ice and sea surface temperature variability in Bering sea and can have significant effects on fish distribution. The fish distribution will affect fur seals, as the crucial relationship between seals food foraging and the abundance of Pollock(Huntington, 2017).

• El Niño also threatens the underwater ecosystem especially the coral reefs, the primary food for some fish species (Huntington, 2017). Fur seals' food storage will be uncertain as to the shift of Pollock and squid; it is difficult for them to find substitutes. Moreover, the competition between fur seals and human fisheries becomes stronger as the fish becomes limited resources. Lack of stable food supply largely threats the fur seals existences.

Harmful algal blooms: effectively lower underwater oxygen levels, threatening marine life and associated with algae-produced toxins(J. Heisler, 2008).

• As the climate changes, Alaska’s annual average temperature increased to 3.5°F from 1949 to 2005 (NOAA, 2013). Through the phytoplankton monitoring in Kachemak Bay National Estuarine Research Reserve(Walker, 2018). The overall increased temperature leads to abnormal warming to tend in the Gulf of Alaska and even transited across the Gulf of Alaska, and Bering sea(Stabeno, 2007). In conclusion, the warming in Alaska is entirely and violently covered the whole region, and the increased temperature seriously influences every part. Thus, through convection, the warmer atmosphere will increase the marine temperature.

• Harmful algal blooms are a common phenomenon in warm areas especially in tropical regions, but recently the more heated Arctic area also triggered this phenomenon. Through Burek’s study, harmful algal bloom becomes more common among marine mammals in Alaskan waters(Burek,2008). When zooplankton, clams mussels eat algae, the algal toxins will accumulate in the tissues, and the toxins will pass through the food chain to high-level predators such as fish, birds who consume the contaminated ones, and induce illness even death(ADAPT Alaska)

• There are some assumptions about the plunging decrease of northern fur seals in recent years. As the former mortality of seals were contributed to hunting, as Alaskans depend on seals furs to resist cold weather and release food shortage. But the hunting number of seals did not show the apparent increase, thus leading to the consideration of another reason. As the warmer temperature makes the ice layer thinner than before, which makes it dangerous for hunters to go out to hunt. Also, without enough ice, the surface friction is difficult to resist the wind above. Thus, make it harder to track (Huntington, 2017). Some scientists assume that the global climate change might contribute to this abnormal decrease number of seals, as the sea level rises reduce seals' living habitats and induce food shortage. Furthermore, many seals pups are experiencing much longer migrating period caused by the harass of strong winds. For all of the reason listed above, it is undoubtedly that the global climate changes have impacts towards northern fur seals (Huntington, 2017).

Qiwen Zheng is in the class of 2021 at St.Lawrence University, major in Environmental study. She is from Chong Qing, China, the middle part of China. Prior to entering college, she completes her education in China. Through the growing and learning experiences, she gradually realized the environment regulating shortages in China. Thus, she chose environmental study as the major, and try to understand the grand overview of environmental issues and regulation methods.