It is proven that the Earth’s overall temperature is increasing. This is causing a rapid decrease in the amount of both land and sea ice throughout the globe. Many seals, including Arctic fur seals and harp seals, depend on this ice for resting, mating, and giving birth to their offspring. This ice is also a habitat to much smaller creatures, a fact that many do not know. For example, many species of algae, krill, and plankton make their living on the sea ice. These three organisms are the foundation of the marine food web.
Seals have a diet that revolves mostly around smaller bait fish, such as herring, and squid. These prey species consume plankton, algae, and krill, which then in turn supply the seal populations with energy needed to stay warm in cold waters and stay active in their everyday lives. The major ice loss that has occurred throughout the globe is greatly decreasing the populations of the basic creatures of the marine food web, therefore decreasing both the herring and squid populations and the seal populations in the polar regions. Since there is a growing lack of ice, there is less space for the plankton, algae, and krill to make a living, causing a decrease in success.
A huge consumption of fish and squid by seals occurs when mother seals go hunting so they are able to produce milk for their offspring. When mothers cannot consume enough fish for both her and her pup, there may not be enough milk produced, hindering the survival success of the pup. In this case, the mother may abandon the pup, very similarly to the situation we see in New England, in search of enough food to sustain primarily herself. There is a study done by Dr. Harry Burton down in Australia that shows there is a significant decrease in survival rate of pups as the we progress into the future.
Seals are a vital part of the ocean food web, controlling populations of smaller fish while also being prey for larger marine organisms such as killer whales and some species of sharks. When the natural balance of the Earth’s processes is broken, there is a chain reaction that occurs, called a positive feedback loop, and chaos in the environment is created. NMLC’s partners, the International Fund for Animal Welfare (IFAW), studied that almost 75 percent of harp seal pups up in the Arctic did not make it due to the lack of sea ice. This can cause an influx in prey fish populations, a decrease in seal populations, and a decrease in seal predator populations, throwing the ocean’s balance off.
As the climate continues to change, us rescuers and rehabilitators have to be on our toes in order to save the animals we care about. As many of the seal species throughout the world are becoming endangered, we do not want to lose them completely due to our own humane actions.
Posted by Megan L
Megan is a summer 2018 intern at the National Marine Life Center. She is a junior at Massachusetts Maritime Academy majoring in Marine Science, Safety, and Environmental Protection.