Steller Sea Lion Research Paper

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Steller sea lions (Eumetiopias jubatus) are the only member of Eumetiopias and are one of the biggest of the eared seals. Steller sea lions feed mainly on fish, and sometimes even various types of shellfish. Many Steller sea lions can be found along the coast of Western Alaska. Generally, Western Alaska has relatively warm summers, cold winters, and mild temperatures during the spring and fall, with the highest amounts of rainfall during the summertime. Steller sea lions have recently come under the scope of many researchers because of their sudden and significant decline of population in recent times. In some places such as the Aleutian Islands, which is an island chain found in the Western part of Alaska, the population of Steller sea lions …show more content…

One hypothesis proposes that the reason Steller sea lions have been declining is because of low prey abundance. Animals should use their energy efficiently when they forage to maximize the net amount of energy gained in relation to the amount time and energy that is spent, but it is believed that the reason Steller sea lions are disappearing in such big numbers is because when prey abundance is lower, that Stellar sea lions are less efficient predators (Charnov, 1976). In a recent study conducted on the effect of prey abundance on foraging efficiency, it was found that the less prey that Stellar sea lions had available, the less efficient they were in foraging (Goundie et al., 2015). In the experiment, the researchers took 4 adult Stellar sea lions and had them dive up and down a tube while recording their oxygen consumption, and dive duration. The sea lions dove between the surface of the water and depths of 10 m, and 40 m, and the reason for this was to simulate diving depths of Steller sea lions in the wild (Merrick and Loughlin, 1997). While the sea lions were diving, researchers fed them pieces of fish through two different tubes that were placed away from each other in order to simulate real foraging movements and prey densities. The researchers fed the seals 12 pieces of fish in the …show more content…

An experiment documenting the effect of feeding low-quality prey like pollock to Stellar sea lions was conducted (Jeanniard du Dot et al., 2008). In the experiment there were two groups of Stellar sea lions, group H and group P. Group H was fed less herring and group P was fed pollock in equal amounts regarding caloric content. After feeding each group the restricted diets, the researchers recorded the foraging behaviors of the sea lions over the summer and the winter. All of the sea lions increased their foraging behaviors during the summer, when prey is abundant, but only group H conserved conserved energy during the winter when prey is less abundant. Group P did not reduce energy consumption in order to use energy more efficiently when it turned winter because they had less energy to use during the winter due to the low-quality diet, and that low-quality diets hurt the sea lions during times of nutritional stress (Jeanniard du Dot et al., 2008). A journal article also documented that young Stellar sea lions were more impacted by a low quality diet (Rosen, 2009). It was seen that young sea lions were more impacted by a low quality diet because of their higher energy requirements, and also their digestive capacity, which means they can't even consume a higher quantity of lower quality fish to compensate. Both of these experiments explain how low quality prey can

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