The Northern Sea Otter Of Southern Alaska
Image from factrange.com
Description and Ecology
The Northern Sea Otter (Enhydra lutris kenyoni) is a distinct group of Otter that forages for its food in shallow coastal waters. They can hold their breath for an average of 5 minutes to dive for their hard to reach food. Their main foods are marine invertebrates such as clams and urchins, which they are able to process with their sharp teeth. They are very social animals and have been known to be seen together with 1,000+ individuals at one time. Northern Sea Otters reach sexual maturity at 2-5 years of age for females and 4-6 years
old for males. In Alaska, most of the pups are born in late spring, and are completely
dependent on their mother until they are weaned at 3-6 months (Alaska Department of Fish and Game).
Image from Point Defiance Zoo and Aquarium
Geographic and Population Changes
Image by Alaska Department of Fish and Game
The Northern Sea Otter in Southwest Alaska is one of the many otter subspecies listed as threatened. The Northern Sea otter is a keystone species, and it's decline has resulted in a significant ecosystem change. Sea otters main food is sea urchins, which when left unchecked overutltilize the sea kelp forest and keep them from becoming established, as it too provides important ecosystem benefits. Sea otters are keystone species in coastal ecosystems such as Southern Alaska, and otter populations were reduced in the 18th and 19th centuries as their fur was highly prized for European consumers. Thankfully, the International Fur Seal Treaty of 1911 protected sea otters from further exploitation. Since 1911 Norther Sea Otter populations have been able to recover. Sea otters are mostly found in high densities in shallow water and/or near islands. However, due to increased pollution resulting in less food and varying temperatures, sea otter populations are once again in a steep decline. "In April 2000, the FWS repeated the 1992 aerial survey of the Aleutian archipelago and counted 1,750 sea otters in this MU, indicating a 73% decline from the 1992 count (Doroff et al. 2003) and an 80% decline from 1965. Aerial and skiff survey data both indicate that the decline began in the late 1980s or early 1990s and proceeded at an average rate of -17.5% per year (Doroff et al. 2003)".
Image from ADFG.gov
Listing Date and Type of Listing
In 2005, the Southerwestern Alaskan population of Northern Sea Otters were listed as Threatened.
Causes and Main Threats to Their Continued Existence
Between 1992-2000, the Northern Sea Otter population fell by 70%. Their numbers fell another 63% between 2000-2003. Biologists believe this might be due to an increase in mortality rates from Killer Whale predation (Alaska Department of Fish and Game). Currently, sea otter populations are declining due to a multitude of factors, which include: predation, disease, oil spills, interactions with fisheries, and overharvest.
Description of Recovery Plan
The Recovery Team divided up the recovery area into 5 different territories which they called "Management Units" (MU). This is due to the major difference in physical habitats among the Alaskan archipelago, which creates different ecosystems.
These 5 MU's are:
- „ Western Aleutian Islands MU
- „ Eastern Aleutian Islands MU
- Bristol Bay MU
- South Alaska Peninsula MU
- and Kodiak, Kamishak, Alaska Peninsula MU
The plan for recovery lists different factors and ranks them from low-to high importance. Things such as habitat loss, lack of nutrition, and prey base are stated as low importance, are are recommended to be regulated if complications or shortages should arise. Also, the management potential for regulating predators is low, as believed that their importance cannot be as significant as some believe and they are large, apex predators that cannot be controlled.
The recovery goal is as follows: "The goal of this recovery program is to control,
reduce, or eliminate threats to the southwest
Alaska DPS of the northern sea otter to the extent
that this DPS no longer requires the protections
afforded by the ESA and therefore warrants
delisting"(FWS Recovery Plan).
Image by theonlinezoo.com
The recovery objectives are as follows:
1. Achieve and maintain a self-sustaining population of sea otters in each MU.
2. Maintain enough sea otters to ensure that they are playing a functional role in their nearshore ecosystem.
3. Mitigate threats sufficiently to ensure persistence of sea otters.
Plan:
1. Develop methods to monitor sea otter effects on marine habitat
2.Identify important habitats of special biological significance
3. Protect important habitats - create more refuge areas
4.Manage impact of human uses
5. Disease control
6. Threat of predation
7. Protect from other natural or human events
8. Implement the recovery plan for southwest sea otters
Want to Learn More? Check out these links for cool facts about sea otters!
Image by the Seattle Aquarium
Alaska Department of Fish and Game
http://www.adfg.alaska.gov/index.cfm?adfg=seaotter.main
U.S. Fish and Wildlife Service
http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=A0HK
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