Unexplained Mortality for Sea Lion Pups and Seabirds
In my last blog, I read about pinniped (sea lions, seals and walruses) evolution. I wanted to see what some current articles were about sea lions. I found an article written last month about how there seems to be massive starvation of sea lion pups in California (http://news.nationalgeographic.com/news/2015/02/150211-sea-lions-pups-stranding-starving-california/ ). This is predicted to be the worst year in a three-year trend. Already animal rescue centers in California have taken in 470 sea lion pups. On the Channel Islands, sea lion pup mortality is estimated to be over 50% this year. Scientists ruled out disease and environmental toxins as causes of this. Their belief is that warm patches of ocean water offshore are affecting the fish populations causing the sea lion mothers to search farther for food. The pups are left behind and are starving, forcing them to head off on their own before they are ready. Sea lions were described as a sentinel species and are supposed to be indicators of ocean health.
This massive death of sea lion pups coincides with another mortality event, that of seabirds, especially the Cassin’s auklets, along the western coast of the US this year (http://news.nationalgeographic.com/news/2015/01/150123-seabirds-mass-die-off-auklet-california-animals-environment/ ). The Coastal Observation and Seabird survey Team (COASST) estimates that there have been 50,000 to 100,000 deaths since the end of October 2014. Autopsies of the birds suggest that they have starved to death. They eat shrimp-like krill and copepods. There is very little food found in their gastrointestinal tracts when they are autopsied. In the last thirty-five years, the largest bird mortality tracked by the US Geological Survey was 11,000 deaths. In Europe, the biggest bird death on record was in 1983 when 57,000 seabirds of various species washed up on the British coast. Although the Cassin’s auklets had a very large increase in juveniles last summer, the magnitude of the die-off has researchers believing that other factors are involved. They think that warmer ocean waters are playing a role in this.
Readers’ opinions on the cause for the bird die-off were mostly that it was due to the millions of tons of radioactive material and cooling water that ended up in the Pacific Ocean from the Fukushima nuclear disaster in 2011 (and contaminated cooling water is still being dumped into the ocean today). The amount of radioactive material released into the environment from Fukushima exceeds that of the Chernobyl nuclear disaster (http://www.naturalnews.com/047053_Fukushima_Chernobyl_radiation.html ) Another report on radioactivity in fish in the Pacific show higher levels of radioactivity persisting than what was previously expected from modeling (http://pubs.acs.org/doi/abs/10.1021/es505064d ). Small amounts of radioactivity from the Fukushima disaster are now found in ocean waters off of California but it is not thought to be at a level that is harmful to humans (http://news.sciencemag.org/asiapacific/2014/11/fukushima-radiation-nears-california-coast-judged-harmless ).
Whatever the cause for the die-off, there could be a starving sea lion pup on UCSB’s beaches. If so, call the Santa Barbara Marine Mammal Center to get help for it (805) 687-3255. They are currently taking care of 100 sea lion pups.