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By Kira Krall
In the 1970s, the United States rolled in massive protections for America’s natural resources. The Marine Mammal Protection, Endangered Species, and Clean Water Acts were all introduced in the early 1970s to reduce human pressure on aquatic systems. While some species like the North Atlantic right whale are struggling to survive, some marine animals are thriving under those decades-old Acts.
The California sea lion is one of those marine animals. In the past 40 years, populations have increased to 250,000 individuals. This study estimated that of the animals that live along the entire length of the United States West Coast, the California sea lion is the first to reach carrying capacity. This means that the population is at its maximum based on the available resources (mainly food) in their range. Seattle-based NOAA biologist Sharon Melin attributes their speedy recovery to their diet. They eat just about anything they can catch and don’t have to rely on feeding seasons as heavily as other marine mammals like dolphins and larger whales do.
While the population increase is a conservation win, it’s caused unruly and even dangerous interactions between sea lions and humans. They’re notoriously stubborn and refuse to leave the comfort of a boat even after being shouted at and sprayed with hose water. The pinnipeds have quite the reputation for sinking boats and damaging docks as they haul their 600-pound bodies out of the water.
Interactions have also become a more direct threat. Three people were bitten by a sea lion in just 5 days in December, with another bite happening in early January of this year. Officials believe it’s a single animal intent on investigating and playing, but just one sea lion bull tooth puncturing the skin sent a San Francisco swimmer to the hospital.
The long-standing battle between sea lions and fishermen has gotten more intense during the population boom. The pressure that individual sea lions put on salmon fisheries was enough for the government to give special permits to Washington, Oregon, and Idaho that allowed them to remove up to 80 troublesome sea lions from salmon hotspots.
While the sea lion/human interaction is a puzzle yet to be solved, the dramatic increase of these animals under federal protection means that the Pacific Ocean might be healthier than we think. Larger populations of larger predators like the California sea lion can’t be sustained without healthy prey. The food web has many levels before it gets to the sea lions, so most if not all of those levels are also thriving.
The study used pup counts and data from tagged animals from 1978-2015.