Austine Luce, Jaime Hilliard, Nicole Smith

   Scientists today have identified nearly 1.5 million species worldwide, although estimates of existing species range from 10-30 million. The current estimates for the number of species going extinct a year ranges from 5,000-50,000, which averages out to about 15-150 species going extinct each day!(Saign, 1994). The ultimate goal for a species is to avoid this ultimate disappearance. There have been many situations in the past where species have gone extinct, but there is a difference between past extinctions and recent extinctions. In the past, the disappearance of a species was under natural circumstances but today they have us, the human, to cope with. Many species today are forced to deal with the problems of human interaction. Humans cause problems such as pollution, overhunting, overfishing, and habitat loss. In all of these situations some are able to adapt and others are dwindling to extinction. The two species Eumetopias jubatus, the Stellar Sea Lion, and Callorhinus ursinus, the Northern Fur Seal, are both experiencing declines in their populations. In order to examine these species any further it is important to know some characteristics of each species.

The Northern Fur Seal male can weigh up to 600 lbs and are 7 feet in length while the females are much smaller weighing up to 110 lbs and reaching 4.5 feet in length (Reidman, 1990). These seals have a short rostrum curved downward, long external ears, and elongated hind flippers. The main diet for the Northern Fur Seal consists mainly of schools of fish and squid. Interestingly, they are prey for not only Great White Sharks and Killer Whales, but also for Stellar Sea Lions. Their range is the subarctic waters of the northern Pacific Ocean, where they spend up to 9 months of the year at sea.

The current estimated population of the Northern Fur Seal is nearly one million, with 10,000 in California alone. However, their population is declining rapidly. Causes for this decline include El Nino, natural deaths, human interaction, and commercial harvesting. El Nino caused a decline of about 60% from the 1982 level in pup production (NOAA). This phenomenon caused a shortage in their food supply, which in turn caused a decrease in milk production for the pups. Some natural declines include disease and mobbing, which is a male fur seal act of aggression where he will ram a mother or pup and often times kill them. The main decline for the Northern Fur Seal though comes from humans. Fishermen see these fur seals as a threat to their fisheries. They carry parasites, eat already low fish populations, and damage fishing gear. For some fishermen, their solution to the fur seals’ presence is to either shoot them, poison them with tainted bait, or kill them with explosives. Another human action that adds to the swift decline of the Northern Fur Seal is seasonal commercial harvesting. Almost like whaling, the fur seals are hunted for their oil and pelts. Humans are also a threat through the problems of pollution. They often drown in fishing nets, get entangled in discarded fishing gear, and die a slow painful death in discarded plastic packing strips. It is estimated that 5% get entangled in the plastic debris and fishing net fragments alone. Also, the overfishing of their prey, such as walleyed pollock, has influence their decline. The Northern Fur Seals also often mistake a plastic shopping bag for one of their prey, a jelly fish. Because of their rapid decline, the Northern Fur Seals have been placed on the threatened species list and are feared to reach extinction in the future.

The second species, the Stellar Sea Lions, are the largest otariid and show marked sexual dimorphism. Males are much larger than the females, reaching a larger size of 2,000 lbs. Adult males also have long coarse hair on their massive chest, shoulders, and back (NMFS, 1992). Generally, Stellar Sea Lions have light brown or tan fur. They eat a variety of fish and invertebrates. They also eat many seals, including the Harbor Seal, Spotted Seal, and the Northern Fur Seal. They range throughout the Pacific rim from central California to Japan, but most live in Alaskan waters (NMFS, 1992).

The current estimated population of the Stellar Sea Lion is 100,000 individuals. The population numbers are dropping and this otariid has been placed on the threatened species list. This species has experienced a drastic decline, over 80% since 1965. Scientists are not sure why their numbers are dropping, but propose many theories on their decline. One idea is that there is a shortage of food, either from El Nino or from a competition with the fisheries. Another theory is that many animals are caught in fishing nets and other plastic trash. One fact that is influencing the population decline is that they do not seem to be reproducing as successfully as necessary for a healthy population. Causes of pup mortality include drowning, starvation, crushing by larger animals, disease, predation, and mobbing. Other theories on population decline include parasitism and disease. Although the Stellar Sea Lion is preyed upon by other species, including the Killer Whale and Great White Shark, there is no evidence to suggest that predation has increased enough in recent years to contribute to the rapid population decline.

The Northern Fur Seal and Stellar Sea Lion are just two examples of species whose populations are threatened or endangered. The Northern Fur Seals’ decline seems to be due to tremendous human impact, while there is no hard evidence for the decline of the Stellar Sea Lion. Many actions have been taken to try to preserve these two species, including buffer zonation, protection laws, and rehabilitation centers. A main part of the protection comes from being under the ESA and the Marine Mammal Protection Act. These two acts have helped aid in some recovery for both populations but are not effective in a few situations. This is because the manpower required to enforce the legislation is very costly. With overhunting and overfishing being regulated, the problem of pollution still continues to threaten these dwindling species populations toward exctinction. There is no right answer in circulation today of a "right" way to save these endagered populations but there is one thing that needs to be recognized. Before we can begin to save a population we must first learn to educate others and organizationally prepare to deal with these small populations.

Animal People "Seals and Sea Lions" http://www.animalpepl.org/97/5/seals.html (June 97) Greenpeace. Death by bureacracy. Greenpeace (Washngton D.C.) Summer 1997. Vol. 2 no.2 pp 22 (2).

Marine Mammal Center "Stellar Sea Lions" http://www.tmmcorg/stellarsl.htm (no date found)

National Marine Mammal Laboratory "Stellar Sea Lion" http://nmml.afsc.noaa.gov/sslhome/Buffer.htm (August 98)

National Marine Fisheries Service. 1992. Recovery Plan for the Stellar Sea Lion (Eumetopias jubatus). Prepared by the Stellar Sea Lion Recorvery Team for the National Marine Fisheries Service, Silver Spring, Maryland. 92 pp.

National Oceanographic and Atmospheric Association "El Nino" http://www.tmmc.org/elnino.htm (no date found)

Riedman, Marianne. The Pinnipeds: Seals, Sea Lions, and Walruses. 1990. University of California Press: Berkeley.

Saign, Geoffrey C. The Green Essentials: What you need to know about the environment. Mercury House: San Fransisco, CA. 1994

The Smithsonian Institute "Northern Fur Seals" (no date found) http://www.bergen.org/Smithsonaian/NorthernFurSeal

Trites, AW. Northern Fur Seals: Why have they declined? Aquatic Mammals. Vol. 18 no.1 pp.3-18, 1992.

Wolfram Research "Mathematica Probes decline in Sea Lion Population" (no date found) http://www.wri.com/discovery/probes.html

A note from Dr. Young:

Population declines in both the Northern fur seals and Stellar sea lions do not have a single, simple explanation. A concern is that it may be a fundamental change in the carrying capacity of the environment for these species. Perhaps their prey populations have been reduced by overfishing, or perhaps the entire ecosystem is changing due to such hard-to-identify causes as global climate change, or perhaps they are the victims of hard to regulate non-point source pollution, including plastics and netting for entanglement and PCB's and other endocrine disruptors which may be reducing their reproductive potential. None of these is very comforting -- they are much more difficult to control than in the good old days when you just had to tell sealers to limit their takes.

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