All existing sea otter, Enhydra lutris , populations have suffered at least one historic population bottleneck stemming from the fur trade extirpations of the eighteenth and nineteenth centuries. We examined genetic variation, gene flow, and population structure at five microsatellite loci in samples from five pre-fur trade populations throughout the sea otter's historical range: California, Oregon, Washington, Alaska, and Russia. We then compared those values to genetic diversity and population structure found within five modern sea otter populations throughout their current range: California, Prince William Sound, Amchitka Island, Southeast Alaska and Washington. We found twice the genetic diversity in the pre-fur trade populations when compared to modern sea otters, a level of diversity that was similar to levels that are found in other mammal populations that have not experienced population bottlenecks. Even with the significant loss in genetic diversity modern sea otters have retained historical structure. There was greater gene flow before extirpation than that found among modern sea otter populations but the difference was not statistically significant.
Sea Otters Research Paper
California Sea Otter Surveys and Research
The number of Shark fisheries has exploded, and there are signs that some Shark populations have declined dramatically. According to one estimate, by researchers at Dalhousie University in Nova Scotia, million Sharks are now killed annually, on average, Baum, Julia K. Myers, Daniel G. Kehler, Boris Worm, Shelton J.
The Missing Sea Otters
You see a sewer or pipe line dumping wastewater or sewage into a river, lake, or ocean. Ask yourself this question: would you drink from that water source? You see a sea otter or a seal swimming in water that has been contaminated by oil from an oil spill.
Sea otters have long been recognized as a classic example of a keystone species, a dominant predator that maintains the balance of kelp forest ecosystems by controlling populations of sea urchins, which are voracious kelp grazers. Since , however, California's kelp forests have declined dramatically, and vast areas of the coast where kelp once thrived are now "urchin barrens," the seafloor carpeted with purple sea urchins and little else. This has occurred even in Monterey Bay, which hosts a large population of sea otters.