DESCRIPTION:
Adult male California sea lions are typically chocolate brown in color and are easily distinguished from females by the raised bump on their forehead called a sagittal crest. Males also grow much larger than females, reaching lengths of 6.5 to 8 feet (2–2.5 meters) and weighing 440 to over 880 pounds (200–400 kilograms). Adult females are usually blond in color, are about 5 to 6.5 feet (1.5–2 meters) in length, and weigh 110 to 240 pounds (50–110 kilograms).
RANGE & HABITAT:
California sea lions range along the Pacific coast of North America and within the Gulf of California. They are often spotted hauled out of the water resting and playing on docks, jetties, beaches, and buoys or swimming or resting nearby.
DIET:
California sea lions are carnivores—they only eat meat. These active hunters prey on a variety of fish, small stingrays, squid and octopus. While they have excellent eyesight both in and out of the water, they often rely on their sensitive vibrissae (whiskers) to detect and follow the movement of prey in dark or murky water conditions.
REPRODUCTION:
Most of the California sea lion rookeries (pupping grounds) are on islands in the southern part of their range from the Channel Islands off Southern California into the Gulf of California. Usually in June or July, an adult female gives birth to a single pup that she nurses for six to twelve months. The mother will leave her pup to search for food. Pups at a rookery will socialize and play in groups called creches. When she returns to the rookery, the mother can locate and recognize her own pup by its smell and vocalizations.
BEHAVIOR:
California sea lions are extremely noisy, social, and playful animals. They are well-known for their distinctive barking. Like other pinnipeds (seals, sea lions, and walruses), California sea lions haul out from water onto land to rest and socialize. They often rest in tightly packed groups at the haul out or at the water’s surface in groups called rafts. Sea lions often surf the waves or porpoise like a dolphin when playing, traveling at high speeds, or feeding.
PREDATORS:
California sea lions are preyed on by large sharks, particularly great white sharks, and orcas/ killer whales.
STATUS & CONSERVATION:
While California sea lions are not endangered or threatened, the population has declined in the past few years due to an unusual mortality event. Between 2013-2016, more than 9,000 California sea lion pups and yearlings stranded along the California coast. Most of the stranded pups were abandoned too early by their mothers and were emaciated, dehydrated, and underweight when rescued. The mothers weaned their pups early because they unable unable to find enough high-quality prey like sardines near the rookeries. As a result, the mothers could not produce enough milk to continue to nurse their pups.
座礁したアシカを見かけたら、必ず地元の海洋哺乳類座礁ネットワークに連絡すること。NOAA Fisheriesには、以下のネットワークの連絡先が掲載されています。海洋哺乳類の救助組織の連絡先が記載されています。これらの救助センターには、十分な訓練を受けた優秀なスタッフがおり、栄養失調のアシカを救助してリハビリを行い、健康な体重になったところで海に帰してあげることができるかもしれません。
DID YOU KNOW?
California sea lions are a type of pinniped; a group of marine mammals that includes all seals, sea lions, and walruses. Sea lions and fur seals are further grouped in the Otariidae family of “eared seals” which share the key characteristic of external ear flaps unlike “true seals” and walruses, which just have a tiny opening on each side of the head.
海岸や波止場で動き回るアシカを観察していると、後ろ足のヒレを体の下に入れ、4本のヒレを使って「歩く」ことができることに気づく。これもアシカの特徴である。また、アシカには翼のような長い前ヒレがあり、これを上下に動かして水中を飛び回る。
動物園や水族館でよく見かける「調教されたアザラシ」は、カリフォルニアアシカである。
カリフォルニアアシカは、ホーンブロワー・ハーバー・クルーズや ホエール＆ドルフィン・ウォッチング・アドベンチャー・クルーズ、その他ほとんどのプライベート・クルーズやパブリック・クルーズで見ることができます。
