Why is the sea otter  classified by the International Union for Conservation of Nature and Natural Resources as one of the endangered species within the marine ecosystem?

Introduction

The sea otter is classified by the International Union for Conservation of Nature and Natural Resources as one of the endangered species within the marine ecosystem. These mammals have a great impact on the marine ecosystem because they keep the population of their prey such as the sea urchins on check. Moreover, through their damaging effect on the kelp forests, the rocky areas of marine ecosystem are promoted through sprouting of the competitive forest species in these areas. The endangering of the sea otter population has therefore led to the ecological consequences in various marine environments such as California sea coasts which have experienced great decline of the numbers of these animals. This is because of the various factors such as oil spillage and hunting which kills the sea mammals endangering into extinction. As a result, various governments have used diverse programs and efforts such as protecting specific areas through prohibition of polluting activities as a way of protecting sea otters. The population of the sea otters was significantly decreased by the sea otter fur trade which began in the 1740s but this trade has been prohibited by many states as a measure of protecting these keynote species from extinction. This paper is a feature article based on a thesis research and it gives a critical review of the sea otter as a keynote species with its substantial influence on the marine ecosystem in addition to a review of the extent to which the species has been endangered. The reintroduction programs which have been made possible as efforts of saving the sea otters from extinction by various states have also been discussed in this paper.

 

Sea Otters as Keystone Species and their Interaction within the Ecosystem

The sea otters are referred to as classic examples of keystone species due to the fact that their presence within an ecosystem has a more profound effect that would not be measured by their numbers or size. Because of their dominance over various prey such as sea urchins and sea floor herbivores, they keep the population of such species in check hence determine their numbers during various seasons of the year. In addition, the sea otters have a great impact on the sea kelp because they graze on the lower stems of this sea vegetation which makes the kelps to die as they drift away from their roots and stems (Vanderzwaag, David and Jeffrey 219). The cascade effect of the sea otters on the kelp forest is experienced due to the loss of nutrients and habitat which is provided by the kelps to the sea ecosystem. The effect of the sea otters is demonstrated by the fact that lack of these sea mammals in the areas around the North Pacific leads to many sea barrens with very many sea urchins (Carter, Sarah, Glenn and Brian 239).The importance of the sea otters in the marine ecosystem surpasses the promotion of kelp forest growth. This is because the rocky areas of the sea have also been profoundly affected positively by the sea otters. The rocky sea areas which are usually dominated by the mussel beds have been improved by sea otters which remove the mussels from these rocks leading to liberation of space which in return allows the competitive species to thrive. Because of the sea otters therefore, the diversity of species in the rocky areas near seas is greatly increased (John 925).

The ability of the sea otters to change the complexity and structure of the marine ecological communities makes them be described as keystone species.  The positive impact of the sea otters in the marine ecosystem includes promotion of sprouting of the kelp forest through consumption of the grazers of this vegetation. Through keeping the population of sea animals such as sea urchins under control, therefore the kelp production is enhanced (Finerty, Shannon, Heidi and Randall 90). The important of the sea otters in the marine ecosystem is demonstrated in the negative impact of their reducing number in California coastlines where the kelp forests are considered the most diverse of the marine ecosystems within the temperate latitudes of the earth. The measures put in place to restore the numbers of the sea otters therefore is aimed at promoting the development of the diverse vegetation within the kelp forests. (Fred 401).

The sea otter being an excellent diver enables it to interact with diverse plantation and animals within the marine ecosystem. The sea otter forages in the floor of the sea where the population of its prey is kept at bay.  In addition, the interaction of the sea otters with the ecosystem includes preying on the invertebrates of the marine life which include mollusks, some species of fish and crustaceans. As a result the population of these animals is controlled by the preying abilities of the sea otters.  Specifically, the sea otters are keystone species which are important in controlling the population of the sea urchins. The importance of this function of the sea otters in the sea ecosystem is the prevention of the sea urchins from inflicting significant damage to the ecosystems of the kelp forest. It is important to note that the eating habits of the sea otters are significantly unique. Its foraging involves using rocks to when dislodging its prey or opening shells of its prey. The tools used by the sea otters make them very unique animals among the sea mammals (Finnoff and John161).

The sea otter has also interacted with the fisheries within the marine ecosystem. The notable keystone feature of the sea otters is the conflict they cause between themselves and the fisheries because the prey species that is part of their diet is also valued by humans as an important source of food (Carter, Sarah, Glenn and Brian 233). The conflict between the sea otters and the fisheries illustrates the competition for the prey shared between the human beings and these marine mammals.

The behavior of the sea otter as a keynote species in its interaction within the marine ecosystem is very unique. This is demonstrated by the fact that these mammals are diurnal and their feeding and foraging habit is unique which usually starts before sunrise with a specific pattern of eating in the morning which is culminated with a rest period in the middle of the day when the animals sleep. The foraging of these animals resumes for a short period in the afternoon and reduces with sunset with others feeding in some periods of midnight (Finnoff and John160). However the eating habits of these animals depend on the amount of food at sea which is equivalent to the number of its prey that is at the sea at a particular period of time.

During its interaction in the marine ecosystem, the sea otter has a keynote social structure which includes resting in groups as a way of ensuring protection from enemies and predators. However each of the sea otter whether juvenile or adult usually feeds alone. The males which are relatively larger in size compared to the female sea otters are important group members of a raft of sea otters which normally contains about 10-100 sea otters (Kuker, Katie and Lance 103).  The breeding season of the sea otters is peak in autumn, a period which is characterized by males defending their territories to exclude other males. The sea otters may be sociable and playful but they are not regarded as social animals because most of their time is spent in solitary due to the ability of each adult to meet its own grooming, hunting and defense needs (Cohn 155).

The sea otters are keystone members of the marine ecosystem because they are eaters of more that 100 different types of sea species. Apart from the sea invertebrates preyed upon by the sea otters, they also eat crabs, limpets and octopuses. This illustrates that the prey of sea otters is of diverse sizes and types (Laidre, Kristin and Ronald 799). In the northern seas, the sea otters have been noted to consume small fish while those in the California coastline ignore prey less than 7cm such as the Pismo clams.

The interaction of the sea otters with the ecosystem varies from region to region. The foraging methods for example vary with the prey types and diet changing as their most preferred diet such as the sea urchins gets depleted (Estes, James, Tim and James 852) Notable also is the fact that their prey habits are significantly affected by the fishing of humans within the coastlines of various seas. The sea otters do not wipe prey species completely from a particular area but a wider variety of prey is consumed by these mammals in areas where there is food scarcity (Fred 405). Moreover, the diet of sea otters is usually more specific in areas of food scarcity as compared to regions where there is plenty of food.

 Sea otters as an endangered species

The sea otters are categorized among the endangered species because they are extensively hunted for their valuable and unique fur which has led to great reduction of their population. Between the years 1741-1911 for example, the hunting for sea otters was most significant and it is therefore said that during this period, their population fell from about 250 000 to only 1500 which makes them one of the highly endangered species which is facing the thereat of permanent extinction from the marine ecosystem (Garshelis, David and Charles 21).

The sea otter fur trade which began in 1740s contributed to the greatest reduction of the number of sea otters. The levels of recovery of these mammals varies from one region to another with parts of East coats of Russia having relatively stable populations with high endangering rates in parts of the California costs (Cray 62). These mammals normally live in costal waters where they stay near the shore. As a safeguard and survival, these animals are usually found in areas that have adequate protection from the thick kelp forest, strong ocean winds and barrier reefs (Finnoff and John160).

Sea otters have been significantly endangered by predators such as sea lions, bald eagles and orcas. However, the sea otters have glands with pungent smells which act as a defense mechanism against predators because most of these predators find the sea otters irritating. As a result some predators have been observed to kill sea otters and not even attempting to eat them (Takahashi 179). Additionally, sea otters especially the young ones may be preyed upon by coyotes and bears on land. In California where sea otters have been endangered greatly, it has been estimated that about 10% of sea otters’ deaths are caused by sharks especially the great white sharks of California (Kuker, Katie and Lance 113).  For this reason, the expansion of the sea otters’ population towards the northern region has not been possible. This illustrates how serious the endangerment of these sea mammals has become within the marine ecosystems. However, there is no documented evidence that sharks eat sea otters despite the fact that many have been found dead with injury marks that are congruent with shark bites (Cohn 154).

The greatest threat to the sea otters in the modern times is oil spills into the sea to which these mammals are vulnerable. The sea otters are endangered by oil which soaks their fur leading to the death of the animals due to lack of air. Inhalation of oil also damages the internal organs of the sea otters such as the kidney and the liver causing them to die. The notable oil spill which killed very many sea otters was the Exxon Valdez oil spill of 1989 (Loomis 387). The oils spills act as a factor which has posed the greatest danger to the sea otters which has resulted to their recent decline in numbers especially in California coastline leading to the assertion that they are facing extinction.

In California, the endangerment of the sea otters has been experienced especially in the late 1990s when the most declines of these mammals was reported (Garshelis, David and Charles 19). This resulted when measures for recovery of the sea otters began to decline or fluctuate. As a result there were increased reports of deaths of sub-adult and adult sea otters in this area. In addition, infection from parasites such as Toxoplasma gondii has been attributed for the decline in the number of sea otters in California. Such infections are fatal to the sea mammals which die as a result and thus carried away by wildcats (Carter, Sarah, Glenn and Brian 247).This is one of the factors which lead to the classification of the sea otters as one of the endangered sea species.

 

 

Reintroduction Programs and Efforts for Sea Otters

Because of the categorization of sea otters as one of the endangered species within the marine ecosystems, various programs, projects and scientific experiments have been carried out as a measure of reintroducing the sea otters to the ecosystem owing to the significant reduction of their numbers (Cray 63). For example recovery plans have been initiated in the Southern sea of the United States where the Marine Mammal commission has been involved in development plans for the sea otters through proper management of fisheries and sea otters in California (Garza 35). The issues that were considered in such plans include the impact of the sea otters on the shellfish fisheries, the status of the sea otter taxonomic population in California and how the development and production of shelf oil affects the sea otters (Keith 727). The recovery plans did not succeed in providing a significant increase in the number of sea otters because their objectives were aimed at protecting the economic activities of the fisheries which led to overlooking of the major problem of the decreasing population of the sea otters in the Southern sea coastlines (Paul 899).

Translocation has also been applied as a recovery goal as a way of reintroducing the sea otter to the marine ecosystems. Translocation was motivated by the fact that the population of the sea otters was declining in the Southern sea (Rebar 494). This method was aimed at translocation the sea otters from the southern sea to a new site so that their distribution and growth would be enhanced. Despite the approval and application of this program, the failure of recognizing the threats to the sea otters due to entanglement of the nets of the fisheries led to inability of the program to cause significant growth of the sea otter numbers within the marine ecosystem which were targeted by the translocation program (Finerty, Shannon, Heidi and Randall 83). The large number of sea otters which dies as a result of entanglement in the fishing nets was described by federal and state sea biologists as the cause of the failure of the translocation program to yield positive results.

In an effort to reintroduce the sea otters to the ecosystem, various scientific researches have also been conducted. For example sea otters were taken from the coastlines of Alaska to Oregon and Washington in experiments aiming at determining whether these mammals could form new colonies in their new environments (Cohn 151). The need to use science as a way of fostering the development of the sea otter population was inhibited by the fact that some environments hindered the growth of these mammals. For example the sea otters released in Oregon from Alaska did not significantly develop as compared to those of Washington which highly flourished. The ecological factors which affect the scientific experiments are very complex that scientists have been unable to determine why the Oregon population disappeared. However DNA experiments were conducted which demonstrated similarity of the Oregon population of the sea otters to those of Alaska (Paulin13).

The International Union for Conservation of Nature and Natural Resources (IUCN) lists the sea otter as one of the endangered species and therefore recommends reintroduction programs that discourage actions which endanger the sea otters. Oil pollution, poaching of sea otters, conflict with the fisheries and predation by orcas are the main activities which have contributed to the endangering of the sea otters (Estes, James, Tim and James 854).  Efforts which are aimed at reintroducing the sea otters have been possible in Canada, Russia and United States through preservation of sea otters within various protected areas. In these countries, pollution activities, oil spillage and dumping of waste in the protected areas are prohibited (Harriet 906). As a result of such efforts, the number of sea otters in these regions has significantly increased with time.

 

Conclusion

The sea otter is one of the endangered species within the marine ecosystems due to activities such as hunting for their fur, predation, conflict with the fisheries and pollution of the sea through oil spillage and dumping waste in seas. These sea mammals which play a great role in preservation of the marine ecosystem through the control of various plant and animal population such as the kelp forest and the sea urchins must be protected from extinction. As a result different states have applied various programs and efforts such as protection of specific areas from destructive activities which endanger the sea otters. In addition, various programs and scientific experiments have been carries such as the translocation program as a way of reintroducing the sea otters to the marine ecosystems. However the success of science in reintroducing sea otters to the ecosystem has been derailed by the ecological factors and the fisheries which affect the development of colonies by these mammals within new environments. Therefore it is recommended that governments apply the reintroduction programs and various legal frameworks which aim at preserving the existence of the sea otter so that it is not eliminated from the marine ecosystem by extinction.

 

 

 

 

 

 

 

 

 

 

 

 

 

Works Cited

Cohn, Jeffrey P. “Understanding Sea Otters.” Bioscience 48.3 (1998): 151-155.

Carter, Sarah, Glenn Vanblaricom, and Brian Allen. “Testing The Generality Of The Trophic

Cascade Paradigm for Sea Otters: A Case Study With Kelp Forests In Northern Washington, USA.” Hydrobiologia 579.1 (2007): 233-249.

Cray, Dan. “What’s Killing The Sea Otters.” Time 168.14 (2006): 62-63. Academic Search

Premier. Web. 14 Nov. 2011

Estes, James A., M. Tim Tinker, and James L. Bodkin. “Using Ecological Function To

Develop Recovery Criteria For Depleted Species: Sea Otters And Kelp Forests In The Aleutian Archipelago.” Conservation Biology 24.3 (2010): 852-860.

Finerty, Shannon E., Heidi C. Pearson, and Randall W. Davis. “Interannual Assessment Of

Territory Quality For Male Sea Otters (Enhydra Lutris) In Simpson Bay, Prince William Sound, Alaska.” Canadian Journal Of Zoology, 88-93 (2010):

Finnoff, David, and John Tschirhart. “Protecting An Endangered Species While Harvesting

Its Prey In A General Equilibrium Ecosystem Model.” Land Economics 79.2 (2003): 160

Fred Weltz . “Aggregations Of Sea Otters (Enhydra Lutris Kenyoni) Feeding On Fish Eggs

And Kelp In Prince William Sound, Alaska.” American Midland Naturalist 161.2 (2009): 401-405.

Garshelis, David L., and Charles B. Johnson. “Sea Otter Population Dynamics and The

Exxon Valdez Oil Spill: Disentangling the Confounding Effects.” Journal Of Applied Ecology 38.1 (2001): 19.

Garza J. C. “The Distribution of Nuclear Genetic Variation and Historical Demography Of

Sea Otters.” Animal Conservation 11.1 (2008): 35-45

Harriet Allen,. “Spatial Habitat Use Patterns Of Sea Otters In Coastal Washington.” Journal

Of Mammalogy 90.4 (2009): 906-917.

John A. Hammond,. “Phocine Distemper Virus in Northern Sea Otters In The Pacific Ocean,

Alaska, USA.” Emerging Infectious Diseases 15.6 (2009): 925-927. Academic Search Premier. Web. 14 Nov. 2011.

Kuker, Katie, and Lance Barrett-Lennard. “A Re-Evaluation of the Role Of Killer Whales

Orcinus Orca In A Population Decline Of Sea Otters Enhydra Lutris In The Aleutian Islands And A Review Of Alternative Hypotheses.” Mammal Review 40.2 (2010): 103-124.

Keith R. Parker,”A Quantitative Ecological Risk Assessment of the Toxicological Risks

From Exxon Valdez Subsurface Oil Residues to Sea Otters at Northern Knight Island, Prince William Sound, Alaska.” Human & Ecological Risk Assessment 16.4 (2010): 727-761

Laidre, Kristin L., and Ronald J. Jameson. “Foraging Patterns And Prey Selection In An

Increasing and Expanding Sea Otter Population.” Journal Of Mammalogy 87.4 (2006): 799-807.

Loomis, John. “Estimating Recreation and Existence Values Of Sea Otter Expansion In

California Using Benefit Transfer.” Coastal Management 34.4 (2006): 387-404.

Paul Bentzen,. “Loss Of Genetic Diversity In Sea Otters (Enhydra Lutris ) Associated With

The Fur Trade Of The 18Th And 19Th Centuries.” Molecular Ecology 11.10 (2002): 899-903

Paulin, Jim. “Survey shows Aleutians’ Steller, Sea Otter Populations Falling.” Alaska Journal

of Commerce 24.29 (2003): 13

Rebar A.H.. “Correlates to Survival Of Juvenile Sea Otters In Prince William Sound,

Alaska, 1992–1993.” Canadian Journal Of Zoology 81.9 (2003): 494-510.

Takahashi, Taiga. “Left Out At Sea: Highly Migratory Fish and The Endangered Species

Act.” California Law Review 99.1 (2011): 179-233.

Vanderzwaag, David l., and Jeffrey A. Hutchings. “Canada’s Marine Species At Risk:

Science And Law At The Helm, But A Sea Of Uncertainties.” Ocean Development & International Law 36.3 (2005): 219-259.