As a consequence of their threatened status, southern sea otters are also recognized as depleted under the Marine Mammal Protection Act. unoccupied habitat have been 17-20% per year. Q. Females are slightly smaller, weighing 14-33 kg and measuring 1-1.4m in length. The primary factors limiting population growth and range expansion of southern sea otters in recent years have been density-dependent resource limitation (where the number of sea otters is in equilibrium with available prey) in much of the central portion of the mainland range and white shark attacks in the northern and southern portions of the mainland range. The southern sea otter population, which once numbered about 16,000 animals, is hovering around 3,000 today. In Elkhorn Slough, a … Contamination of their fur by oily substances can destroy its insulating properties and lead to hypothermia and death. Sea otters in Prince William Sound were from the original surviving 1911 population… However hunting which began the downfall of the sea otter in the Northern Pacific Ocean. answer choices . Males weigh 22-45 kg and are 1.2-1.5 m in length. b. increases slowly. This rapid recolonization exceeds the theoretical maximum population growth rate, suggesting that immigration from outside Glacier Bay is also likely occurring (Esslinger et al. The data for Figure 3 shows all sea otters the researchers encountered, while the data for Figure 4 shows sea otters with radio tags. 2493 Portola Road, Suite B The latest census and stranding information is available at www.werc.usgs.gov/seaottercount. The latest count of this threatened species shows their population dropped to just 2,711, a decline of 3.6 percent. Alaska Peninsula. The International Fur Seal Treaty protected … McKnight, 1973). Figure [25] The translocation program allowed the reintroduction of sea otters to San Nicolas Island but also required the removal of sea otters from a âno-otterâ management zone. But, despite all of this, it is safe to conclude that overall, the total sea otter population has increased over the 10 year span shown in the graph. The tail comprises less than a third of the body length. According to the draft assessment, the regions otter population appears to be growing at a rate of 12 to 14 percent per year. December 29, 2003 Suppose you census a population of sea otters this spring and count 140 individuals. Graph showing regional trends in abundance of sea otters (Enhydra lutris nereis) along the mainland coast, central California, and at San Nicolas Island, southern California ..... 6 4. However depleted otter populations throughout Alaska’s Aleutian Islands still remain at 50% of their 1980 abundance. 2 show growth patterns observed in three sea otter population stocks in Figure Fig. In the next two examples, students will be able to see how sea otter populations compare to the total population and to the adult sea otter population. Arsenic accumulation in sea otters in Japan (Kubota et al. The effort to document all stranded southern sea otters continued. This web Otters feed on sea urchins, which in turn keeps them from overgrazing on kelp. CALIFORNIA SEA OTTER POPULATION ANNUAL SURVEY – survey history and methodology . In 2001, the population consisted of 36 individuals. site was created by Lynn Tran at the North Carolina State University, Department Adult sea otters typically weigh between 14 and 45 kg (31 and 99 lb), making them the heaviest members of the weasel family, but among the smallest marine mammals. The body condition of sea otters in areas of the range with low per-capita prey availability strongly influences their susceptibility to additional stressors. If the sea otter population was not expanding and reclaiming its lost habitat, I would consider relocation again. (a) Construct a graph that shows how otter density depends on kelp abundance, using the data shown above. Q. Graphs in Figure Sea otters act to maintain a wide variety of other populations in the community. As predators, sea otters maintain the balance of the kelp ecosystems. In this article you’ll get to know about the sea otter population as well as how many sea otters are left in the wild. Once an endangered species as a result of fur trading, otter populations recovered and appeared very healthy and robust in the early 1980s. initiate translocated populations. Based on the graph, how did the California sea otter population change from 1997 to 2007? Tags: Question 19 . As a result, their energetic requirements are high, and they consume an amount of food equivalent to about 25 percent of their body mass per day. c. reaches carrying capacity. Map of Alaska indicating general locations of three genetically The graph above shows how the sea otter population has inclined since the oil spill in the Prince William Sound, Alaska in 1989. impacting the Southwest stock since the other stocks continue to prosper. C Chemical runoff from a factory kills many crabs and small fish in the area. Facebook Twitter Share. Sea otters eat sea urchins, which feed on seaweed. Because of their consumption of large quantities of marine invertebrates, sea otters play a significant role in nearshore marine ecosystems of the North Pacific Ocean, enhancing not only kelp forests but also seagrass beds. One of the most staggering facts from this survey was that when sea otters recolonized the area in 1984, the eelgrass population increased by 600%, which definitely displays that sea otters have something to do with the population … Q. Isle Royale is located in Lake Superior. 1b. Powered by Create your own unique website with customizable templates. It is estimated that 90% of world's Scientists researching Pacific sea otters find that many members of the population are infected by a parasite, and a number of the sea otters must be destroyed to save the entire sea otter population. Send keyboard focus to media. We use a three-year running average of the total number of sea otters counted in spring surveys along the mainland and at San Nicolas Island to derive the range-wide index of relative abundance, which is now 3128, down from 3186 in 2017. Results of surveys through 2000 demonstrated a significant increase Why are they important? 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