Sea lions include a total of six extant species. Three species of sea lions are threatened by the International Union for Conservation of Nature (IUCN) and one is threatened under the US Endangered Species Act (ESA). This article discusses the status and threats of these different species and what is being done to protect the most threatened populations.
Endangered species of sea lions
The genetically isolated Australian sea lion is believed to number 6,500 mature individuals in a declining global population across Western and South Australia and is IUCN and state-level threatened within its extant range.
Similarly, the Galapagos sea lion was listed from vulnerable to endangered by the IUCN in 2008 and is fully protected under Ecuadorian law after being hunted to near extinction for its fur in the early 20th century. . The species declined by almost 24% following the last significant El Niño event in 2015.
Also in 2015, the IUCN added the New Zealand sea lion to the endangered species list, citing a 98% chance of extinction in the species’ largest general population in just five generations. At the time, there were just over 3,000 people left in total.
On the other hand, the Steller sea lion is considered “not threatened” by the IUCN but endangered under the ESA and protected under the Marine Mammal Protection Act. Why? According to the IUCN, a large increase in the Loughlin Steller sea lion subpopulation between 1985 and 2015 has offset losses elsewhere.
Did you know?
Once abundant along the Pacific Northwest coast, the Japanese sea lion officially became extinct in 1990, although there have been no documented sightings of the species since the late 1950s.
Sea lion species are vulnerable to pollution, climate change, bycatch, and diseases introduced by other species. Gillnet fishing complications pose a significant threat to Australian and New Zealand sea lions, while Galapagos sea lions are more susceptible to climate change, disease and pollution.
Like all coastal marine animals, sea lions are threatened by ocean pollution. Since they are the main predators, toxins from pollution or harmful algal blooms that affect smaller prey species can accumulate in sea lions, leading to neurological changes, behavioral changes or even death.
Plastic waste at sea and on land frequently entangles sea lions. At the same time, oil spills have been shown to pose a significant danger to Steller sea lions. A study found that Steller sea lions were the fourth most vulnerable species to oil spills in British Columbia, after sea otters and several species of killer whales.
In 2021, scientists made headlines when they finally discovered the cause of a mysterious cancer that had been killing California sea lions for 40 years. Unfortunately, the culprit was toxic chemicals from industrial waste, pesticides, and oil refinery waste.
All sea lion species are vulnerable to the effects of climate change on ocean conditions. Especially since warming temperatures lead to weaker currents, it can impact the abundance of fish prey in sea lion habitats. Scientists who studied a three-decade sustained ocean warming event in the Gulf of California linked it to a 65% decline in the sea lion population between 1991 and 2019.
Studies on San Miguel Island off Santa Barbara have also found that sea lion pup weight declines during El Niño events, disrupting spawning times and the locations of sardine and anchovy populations. In the years leading up to 2016, animal rescue centers saw large numbers of stranded and underweight baby seals. A NOAA Fisheries study linked to a decline in populations of high-calorie sardines and anchovies (rich in fats essential for the early development of sea lion pups). Nursing females were forced to feed on prey such as market squid and rockfish, which contain much less fat and calories, and therefore struggled to meet the nutritional needs of their young.
Although the greatest historical threat to sea lions – intentional killing and hunting – has mostly disappeared, some animals are still killed accidentally in net fisheries. Commercial fishing can also alter the distribution and abundance of sea lion prey, affecting reproductive success and the overall health of the species. When sea lions become entangled in fishing gear like traps or gillnets, they can drag and swim long distances, become fatigued, seriously injured, or compromise their ability to feed.
Getting caught in various fishing nets is a major cause of death for endangered New Zealand and Australian sea lions, which are attracted to bait material in lobster traps. Young puppies in particular are at risk of drowning when they cannot escape from the potties.
The highly concentrated nature common to sea lion subpopulations makes them more vulnerable to disease outbreaks. In 1998, 2002 and 2003, epizootic outbreaks in the Auckland Islands resulted in early pup mortality of 50%, 33% and 21%, respectively, in New Zealand sea lions. The cause of the outbreak in recent years has been found to be related to severe respiratory disease caused by Klebsiella pneumoniae bacterium.
In 2001, during a viral outbreak of canine distemper in the Colony of San Cristobal, Santa Cruz and Isabela Islands, it was actually recommended that all dogs on the islands be vaccinated to reduce the risk of transmission to lions. of the Galapagos Sea.
what we can do
Like seals, sea lions belong to a group of marine mammals known as pinnipeds that live primarily in the ocean but are able to come to land for long periods of time thanks to their adapted leg-like fins. For this reason, they are not the easiest to count, identify and monitor. Scientists in Glacier Bay, Alaska are using a combination of counts from aerial photographic surveys and in-water observations from ship surveys to help fill the gap.
When it comes to endangered sea lion species, countries like Australia have specific recovery plans. In 2018, the Western Australian government established a series of Sea Lion Protection Zones around known breeding colonies where gillnet fishing is strictly prohibited. In South Australia, a decade-long program by the Australian Marine Conservation Society and Humane Society International to prevent the use of gillnets near sea lion colonies has helped reduce sea lion mortality by 98%. fishing nets in these areas.
Studies have shown that establishing more marine reserves in sea lion habitats can increase prey fish diversity, biomass, and even total population numbers. Community marine reserves could also help improve the resilience of marine mammals to certain climate-related effects, as well as the health of marine ecosystems, directly benefiting sea lions and fishermen.
Save endangered species of sea lions
- Make a symbolic sea lion adoption with the World Wildlife Fund to help support conservation efforts.
- Call your local marine animal shelter or sanctuary when you find baby sea lions that have washed up on shore, or any dead, injured, or entangled sea lions. Remember to keep a safe distance from all sea lions (and all wildlife, for that matter) for your protection and theirs.
- Limit your use of disposable and single-use plastics, participate in a coastal cleanup and dispose of fishing lines responsibly.