Southern sea otters are a
subspecies of sea otter found along the California coast.
This fact sheet will focus only on information related
to this subspecies. For general sea otter information,
refer to the Sea Otter (Enhydra Lutris) fact sheet.
Southern
sea otters share the basic physical characteristics of
all Enhydra lutris sea otters, but they are the smallest
in size when compared to the Northern sea otter (Enhydra
lutris kenyoni) and the still larger Asian sea otter (Enhydra
lutris lutris). They are described as having narrow skulls
with a longer rostrum and smaller teeth than the other
two subspecies. Southern sea otters are less likely to
haul out on land than northern sea otters (Davis, Lidicker,
1975).
Historically, there were believed to be some 20,000
southern sea otters on the West Coast of North America,
from Oregon to the Mexican Baja Peninsula. They were hunted
relentlessly from 1784 to 1840, and were believed extinct
until a group of around 40 individuals was spotted in 1914.
Sea otters were again found near Big Sur in 1938. Thanks
to the International Fur Trade Treaty of 1911, these remnant
populations of sea otters were not subject to hunting,
and over time, their population started to recover. They
now inhabit half their former range, from Half Moon Bay
near San Francisco to Point Conception near Santa Barbara,
CA.
There have been some efforts by conservationists to increase
the range of southern sea otters by translocating them
to areas in their former range. From 1987 to 1990, 140
otters were moved to San Nicolas Island, not far from Los
Angeles. This population was projected to reach 400 or
more by the year 2000. The effort proved a failure, as
15 years later, there were only 40 sea otters remaining
at San Nicolas.
 |
| Picture
of southern sea otter or California
sea otter,
Enhydra lutris nereis,
floating on its back, British
Columbia, Canada, North Pacific
Ocean |
Image
#: 001323 |
|
|
|
Kingdom:
Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Carnivora
Suborder: Caniformia/Canoidea
Family: Mustelidae/Mustelids
Genus: Enhydra
Specific: lutris
|
|
Fortunately, southern sea otters have fared
better in their current natural range than they did on
San Nicolas. In spring of 2007, scientists of the U.S.
Geological Survey (USGS), who researched southern sea otters
throughout their range, recorded a count of 3,026 southern
sea otters. This represented a 12.4% increase over the
previous year's count of 2,692. Scientists were encouraged
by the 3-year running average increase, which is used to
evaluate the overall trend in sea otter numbers.
Despite
the good news about southern sea otter numbers, sea otters
have no guarantee of survival as a subspecies. Some researchers
projected that the number of southern sea otters should
have been 13,000 by now. In 2007, a record number of southern
sea otter carcasses washed up on shore, including many
breeding age females. Causes of death were various, including
shark attacks, bullet wounds and outboard motor injuries,
but one quarter of the fatalities were due to illness traced
to protozoan parasites, Toxoplasma gondii and Sarcocystis
neurona. Both of these parasites are found in cats, so
scientists speculate the outbreak originated with the disposal
of cat litter into toilets, which were then flushed to
the sea. Add to this the deaths caused by toxic algae blooms
triggered by fertilizer runoff, deaths from toxic chemicals
found in filter feeding shellfish, and deaths from accidental
capture in gill nets, and there is genuine cause for concern
about the future of the southern sea otter.
The U.S. Federal
Endangered Species Act (ESA) lists California sea otters
as a Threatened species. California state law lists it
as a fully protected mammal by the Marine Mammal Protection
Act.
All sea otters now in existence are descendants of
a fairly small number of exploitation era survivors. Consequently,
there is little genetic diversity among sea otter populations,
making them particularly vulnerable to disease or sudden
environmental change.
Alternate names: Southern Sea Otter,
California Sea Otter
Links to SeaPics.com fact sheets on
the other two subspecies of sea otter:
Asian sea otter
(Enhydra lutris lutris) of Japan and Russia
Northern sea
otter (Enhydra lutris kenyoni) of the Aleutian Islands,
mainland Alaska, British Columbia, Canada and the U.S.
State of Washington
© Southern sea otter information
assembled
from on-line sources by Kevin
Miller on June 10, 2008 for
Seapics.com.
http://www.jstor.org/pss/1381977 soundwaves.usgs.gov/2007/09/fieldwork2.html
http://soundwaves.usgs.gov/2005/08/fieldwork3.html
http://www.time.com/time/magazine/article/0,9171,1538645,00.html
http://www.defenders.org/programs_and_policy/wildlife_conservation/imperiled_species/sea_otter/background_and_recovery/california/index.php
http://www.defenders.org/programs_and_policy/wildlife_conservation/imperiled_species/sea_otter/background_and_recovery/california/translocation.php
http://www.defenders.org/programs_and_policy/wildlife_conservation/imperiled_species/sea_otter/background_and_recovery/california/successes.php |
