White sharks rebound in California

The long arc of environmental regulation is rebuilding a damaged ecosystem.

 

Most of the millions of beachgoers who flock to southern California’s coast never notice the baby sharks swimming laps just offshore, but that’s starting to change. The sharks aren’t on the prowl for sunblock-glazed snacks: the Southern California Bight – the coastal waters from Santa Barbara to the U.S.-Mexico border – is a white shark nursery. It’s where the young predators hide out, stay warm, and learn to hunt, before joining adults in deeper seas. Though their species has long been declining, baby white sharks are making a surprising comeback in the Bight.

Their return tells a bigger environmental success story: federal and state regulations stretching back 40 years have curtailed pollution and repaired the marine food web that includes white sharks (formerly called great white sharks). “You can’t have an ecosystem that’s badly damaged and have predators,” Chris Lowe, director of the Shark Lab at California State University-Long Beach, says.

Chris Lowe (in red) returns a juvenile great white shark to the sea, off Santa Monica beach. Baby white sharks are showing up in larger numbers, indicating a healthier marine ecosystem.
Steve McNicholas

The Bight’s baby white sharks declined for a number of reasons, Lowe says: poor water quality, their decimation as gillnetting bycatch, and the near-extirpation of the prey that adult sharks rely on. Likewise, no single environmental law saved them. Instead, a suite of regulations enacted from the 1970s to the mid 1990s helped restore southern California’s coastal ecosystem enough for its white shark nursery to eventually start recovering. (See timeline).

In 1994, California passed a white shark fishing ban and a gillnet fishing ban, both of which protected baby white sharks. Since then, researchers have documented baby shark populations growing in the Bight. The sharks shape the Bight’s ecosystem, in turn. California’s seals and sea lions have rebounded so well under the Marine Mammal Protection Act, predators are needed to cull their populations and keep them healthy, Lowe says. Meanwhile, development projects such as marinas and residential buildings constructed in California’s estuaries have pushed stingrays out of their traditional habitats and into coastal waters, where the rays provide easy food for baby white sharks. In future, the sharks’ appetites might even make people safer: Stingrays injure beachgoers on California’s coast far more frequently than white sharks do, Lowe says, though he acknowledges that’s a hard argument to sell to a shark-phobic public.

“You hear about all the bad things we’re doing to the planet, to the ocean: the pollution, overfishing, global climate change,” Lowe says. Marine life faces continued threats, but the recovery of the shark population is a sign that humans are doing something right. “Maybe at a regional scale, but at least it’s a start.”