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Why Sea Otters are under Threat
by Heather Windmiller
Sea Otter Awareness Week is celebrated at the end of September through early October. Every year, Defenders of Wildlife organizes and promotes this event in order to teach people about the integral role that sea otters play in the nearshore marine ecosystem and to promote research and conservation programs. Check out THIS link for further information.
In an article titled, California Sea Otter Threats, Defenders of Wildlife states, “The California sea otter was listed as "threatened" under the Endangered Species Act in 1977, and at that time, the number one threat identified was oil spills.”
Now, in 2010, Sea Otters are not only endangered by oil but face other hazards as well, all posing a deadly threat to their survival !
Group of sea otters
“Starting in 1998, disease has contributed to about 40 percent of the number of sea otter deaths each year. This is an unprecedented figure for any wildlife population.”
Some diseases causing peril to the sea otter populations include fatal infections from worms, bacterial infections, infections of the brain and fungal infections. Pesticides such as DDT “persist in the environment and enter into the marine ecosystem in run-off” from agricultural systems".
"In recent years, including a suspected spike in April 2004, dead and dying sea otters are being found with domoic acid – a toxin produced by decaying algae. While still an unconfirmed mystery, scientists suspect the algal blooms that result in the release of domoic acid are linked to the increase in pollutants in our nearshore waters.”
Finally, there is oil pollution -- the No. 1 threat to sea otters. "Oil pollution can cause hypothermia and organ damage in sea otters. When their fur becomes matted by oil, the insulation is impaired. Sea otters can’t maintain heat and they die from exposure.”
Read more about it HERE.
USFWS National Digital Library
Sea Otter oil
by Karl Kenyon
Interactions with Fishing Gear
"Fishing gear used by commercial fishermen to catch specific types of fish can be lethal to non-target species.” The problem is known as bycatch, “the capture of a non-target species” and it is a particular problem to the southern sea otter which has been federally listed as “threatened” and has also been “declining in recent years". Gill nets, trammel nets, and live fish traps all poses hazards to the sea otter population.
Gill nets, which are left out unattended for 12-24 hour periods, hang like curtains in the water with weights at the bottom and floaters at the top. Sea otters drown in the nets when they dive, foraging for food, and become entangled in the nets.
USFWS National Digital Library
Biologists setting gill net for collecting fish samples
by Jose Otto
Trammel nets are large mesh nets, left out unattended for 24 hour periods, also result in “entanglement and drowning of non-target species such as the sea otter.”
Live fish traps do just what the name implies: catch fish live. "Fish and other marine animals swim into the traps but cannot swim out. Though a dead sea otter has not been documented in a live fish trap off the California coast, it is believed that California sea otters do have encounters with live fish traps that may prove deadly."
For more information, please check out this following site HERE.
Acidification of the oceans
“Acidification of the oceans due to excess carbon dioxide in the atmosphere. Roughly a quarter of the carbon dioxide emitted each year ends up dissolved in ocean water, a process that forms carbonic acid, which eats away at the shells of the calcium carbonate mineral shells common to coral reefs, shellfish species like clams, mussels and oysters, and sea urchins and starfish – vital food sources for sea otters and other marine predators.”
This information can be found in the following link HERE.
Southern Sea Otters
