There are six known species of sea lion in the Otariidae family of Pinnipeds. These mammals are distinguished from most seals by their visible ears, long front flippers, and ability to walk using their flippers as limbs. Sea lions are found in oceans throughout the world and some will even swim far inland through coastal river systems.
The California sea lion is one of the most numerous marine mammal species in the world, with an estimated population of nearly 200,000 animals. Adult males, which are generally somewhat larger than their female partners, can grow to be 8 ft (2.4 m) long and can weigh up to 860 lbs (390 kg.) You will often find this species at marine parks performing in shows, as they are quite intelligent and easy to train. During mating season in early summer, the animals gather in huge numbers along the North American west coast, engaging in mating battles and rearing young pups.
Largest of all sea lion species is the Steller sea lion of the Northern Pacific Ocean. These animals are born weighing over 50 lbs (23 kg) and adult bull males can reach a weight of 2500 lbs (1100 kg) within 5 years. The Stellar sea lions range lies mostly around Alaska, where experts have noticed a startling and unexplained drop in population since the end of the 20th century. Many observers believe that competition for food stocks with fishermen has damaged the natural diet of the sea lions, leading to their dwindling numbers around the Aleutian Islands. Since 1990, they have been listed as endangered under the laws of the US Endangered Species Act of 1973.
The Australian sea lion is unique to the waters surrounding Australia, and was hunted to near extinction by European settlers in the 18th Century. In 1972, Australian government passed the National Parks and Wildlife Act that protected several species, including the dwindling sea lions that have since seen rebounding numbers. Studies suggest that this species has unusual breeding cycle of 18 months, and the females will return to the beaches they were born on to give birth.
In South America, sea lion pups are born very dark brown or black, and slowly lighten in color as they age. Males grow a lion-like mane of fur, and feature an upturned snout. South American sea lions were hunted heavily for centuries, but are now largely protected by local laws. They are often preyed on by orcas, leopard seals, and the occasional coastal-dwelling cougar. The sea lions themselves are skilled predators, and have been observed eating penguins.
Similar in appearance to the California species, Galapagos sea lions are known for their large mating communities, which can consist of one bull and up to thirty cows. While these animals are protected by local law, large-scale poaching has become a problem in the 21st century. In 2001, a bachelor colony of 35 males was discovered, showing obvious signs of having teeth and body parts removed by hunters. More mysteriously, in 2008, 53 animals including 13 pups were found clubbed and abandoned.
The Japanese sea lion was somewhat larger than their California cousins, and lived in caves and on sandy beaches along the Japanese coast. They were hunted to extinction in the 1950s after enormous hunts for meat and fur. In 2007, a joint commission was started by several nearby nations to search for any remaining living specimens in order to start a re-introduction program.
Sea lions are extremely important members of ocean eco-systems, and like most predator species help maintain sustainable populations of other animals. While some species, such as the California family, maintain extremely healthy populations, others are endangered by competing fishermen, pollution and climate change problems. Both the Galapagos and South American species were severely affected by the El Niño weather patterns of the late 20th century, providing evidence that severe climate problems can greatly influence species survival. To help preserve the various species, consider donating or volunteering with a reputable conservation agency, or using only biodegradable and environmentally friendly products.