BEACH AND BAY

Turtle trouble

Entanglement, boat strikes threaten endangered animals in South Bay

By AMY STEWARD

Sea turtles have been around for more than 100 million years. It’s no wonder they are a symbol of longevity. Turtles also symbolize patience, wisdom and endurance. Sadly, today sea turtles are on the endangered species list.

Many people are surprised to learn there are 60 to100 green sea turtles in South San Diego Bay at any given time. Before the South Bay Power Plant in Chula Vista was decommissioned in 2010, it created a whirlpool of sorts in which turtles liked to dwell.

After the plant was shut down, scientists worried the turtle population would decline, but this proved not to be the case. In fact, the South Bay green sea turtle population has risen in recent years due to an increase of protected turtle nesting beaches in Mexico.

Adult females migrate to these beaches every two to three years to lay their eggs. Returning juveniles mature in South San Diego Bay for several years before embarking on their own sojourn.

San Diego is an important habitat for green sea turtles, which have been recorded in the bay since the mid-1800s. South Bay, which is shallower than the central and northern parts of San Diego Bay, has lots of eel grass beds and is designated as the San Diego Bay National Wildlife Refuge.

RICHARD CAREY | DREAMSTIME Green sea turtles can live for about 70 years. Females do not reach maturity until they are at least 25 years old.

STEVE HYMOND | DREAMSTIME

Pollution in the bay and speeding boats are the biggest threat to the endangered green turtles living in San Diego's South Bay.

But while the area’s turtle population has increased, they are facing numerous threats.

The biggest threats to turtles in the bay are entanglement and boat strikes, said Dr. Jeffery Seminoff, head of the Marine Turtle Ecology & Assessment Program with the National Oceanic and Atmospheric Administration (NOAA) Southwest Fisheries Science Center, who studies sea turtles worldwide and in San Diego Bay.

Sea turtles are increasingly at risk with the proliferation of marine debris in the bay. A green sea turtle died in May after it became entangled in an anchor line abandoned on the bay’s bottom. The large male turtle, which was foraging on the sea floor, became ensnarled and was unable to reach the surface to breathe and drowned.

NOAA partners with Sea World and the San Diego Unified Port District to help injured turtles, but, Seminoff said, “We need everyone thinking about what is going into the storm drains, taking care to properly dispose of trash and recycle, and obeying the speed limits in the bay when boating to protect the turtles that inhabit South Bay.”

Speed limits are posted specifically to protect the turtles, but boaters tend to ignore them. “To protect the turtles,” Seminoff said, “people need to slow down.”

These endangered animals also face other threats. Pesticides and heavy metals from industrial runoff are causing acute health problems. Most regional turtles have elevated white blood cell counts, which is associated with an immune response to fight disease.

Another big threat to sea turtles is climate change. While gender in most

HOW TO HELP THE GREEN TURTLES IN SOUTH BAY

• When you see a sea turtle, do not approach it. • Become a citizen scientist and let NOAA know where you sighted the turtle. Use a latitude/longitude app on your phone and send the information about your sighting to swfsc.turtle-sightings@noaa.gov. Be sure to include information about the weather, water temperature and location. • Participate in beach cleanups along San Diego Bay and in your neighborhoods. Everything flows to the ocean. • Stop using single-use plastics. Plastic bags mimic jellyfish, a favorite food for turtles. Each year, 11 million metric tons of plastics enter the ocean, while an estimated 200 million metric tons circulate in the world’s oceans.

other species is established during fertilization, a sea turtle’s sex is established after fertilization by ambient temperature. Warmer incubation temperatures produce female hatchlings, while cooler temperatures produce males. This is called temperature sex determination.

“We are witnessing the feminization of sea turtles with only one in four sea turtles now being male,” Seminoff said.

The concept of a turtle carrying the world on its back has been seen in mythology in cultures for millennia, from China to India and among Native Americans. Humans must now step up to carry some of the weight to protect this incredible species. ■

Amy Steward is president of Emerald Keepers.

TRACY TEMPEST/ NOAA PERMIT #18238-08

The remains of a drowned turtle are examined in South Bay.