Sea Lion Challenges
Wild California sea lions live an average of 20-25 years. During their lifetime they may encounter many challenges both natural and human-caused. Natural predation either by white sharks or killer whales (orcas) is the foremost challenge to sea lions. These top predators frequently feed on sea lions and seals in the ocean near the Farallon Islands. They are efficient; rarely do we observe a sea lion at K-Dock with a fresh bite wound or scar. Unfortunately, it is more common for us to observe suffering sea lions entangled in nets, fishing line or packing straps. Sea lions are curious and use their noses to investigate floating objects, so the plastic line, net or strap is usually around their necks. Sadly, entangled animals are often otherwise healthy and therefore difficult to rescue. They may eventually die from infection, strangulation or malnutrition. Other human-caused problems for sea lions include ingestion of plastic trash and gunshot wounds.
Just as deadly, but less noticeable are challenges caused by disruptions in natural cycles and the influence of climate change. By keeping track of trends in the total numbers of sea lions and observing the healthy, injured, sick and underweight sea lions at PIER 39, we can better understand these challenges. Sea lions are mammals, like us, and they encounter similar diseases and problems such as pneumonia—caused by parasitic lungworms, bacterial infections like leptospirosis, which affects their livers and kidneys, and cancer caused by pollutants such as DDT and heavy metals in the environment. Natural toxins from harmful alga sicken and kill sea lions and can endanger humans if we eat infected seafood. Other challenges include malnutrition due to maternal separation or lack of prey due to the effects El Niño or other climatic changes and environmental factors.