Steep decline in giant sea turtles seen off US West Coast

Scott Benson, an ecologist and leatherback turtle expert with the National Oceanic and Atmospheric Administration Fisheries Service, based in Moss Landing looks out over the water from his research boat in Monterey, Calif., on March 25, 2021. Benson has studied western Pacific leatherback turtles for decades and recently co-authored a study that shows an 80% population drop in just 30 years for one extraordinary sub-group that migrates 7,000 miles across the Pacific Ocean to feed on jellyfish in cold waters off California. (AP Photo/Haven Daley)

In this July 5, 2017, photo provided by Kate Cummings, is a leatherback turtle swimming in the Pacific Ocean near Moss Landing, Calif. All seven distinct populations of leatherbacks in the world are troubled, but a new study shows an 80% population drop in just 30 years for one extraordinary sub-group that migrates 7,000 miles across the Pacific Ocean to feed on jellyfish in cold waters off California. Scientists say international fishing and the harvest of eggs from nesting beaches in the western Pacific are to blame. (Kate Cummings via AP)

In this Sept. 10, 2002, photo provided by Scott Benson, a leatherback turtle is seen in Monterey, Calif., during a scientific expedition to research the turtles' migration patterns. All seven distinct populations of leatherbacks in the world are troubled, but a new study shows an 80% population drop in just 30 years for one extraordinary sub-group that migrates 7,000 miles across the Pacific Ocean to feed on jellyfish in cold waters off California. Scientists say international fishing and the harvest of eggs from nesting beaches in the western Pacific are to blame. (Scott Benson via AP)

In this December 2006 photo provided by Karin Forney, is Scott Benson, an ecologist and leatherback turtle expert with the National Oceanic and Atmospheric Administration Fisheries Service, posing with a female western Pacific leatherback turtle on a nesting beach on Santa Isabel Island in the Solomon Islands. All seven distinct populations of leatherbacks in the world are troubled, but a new study shows an 80% population drop in just 30 years for one extraordinary sub-group that migrates 7,000 miles across the Pacific Ocean to feed on jellyfish in cold waters off California. Scientists say international fishing and the harvest of eggs from nesting beaches in the western Pacific are to blame. (Karin Forney via AP)

In this aerial photo provided by Joel Schumacher, scientists in a research boat pursue a Pacific leatherback turtle in the Pacific Ocean off California in September 2016. All seven distinct populations of leatherbacks in the world are troubled, but a new study shows an 80% population drop in just 30 years for one extraordinary sub-group that migrates 7,000 miles across the Pacific Ocean to feed on jellyfish in cold waters off California. Scientists say international fishing and the harvest of eggs from nesting beaches in the western Pacific are to blame. (Joel Schumacher via AP)

In this photo provided by Heather Harris, taken Sept. 25, 2007, in the waters off central California, scientists including Scott Benson, at far left, can be seen posing with a giant western Pacific leatherback sea turtle as they take measurements and attach a GOP satellite tracking device to its shell. All seven distinct populations of leatherbacks in the world are troubled, but a new study shows an 80% population drop in just 30 years for one extraordinary sub-group that migrates 7,000 miles across the Pacific Ocean to feed on jellyfish in cold waters off California. Scientists say international fishing and the harvest of eggs from nesting beaches in the western Pacific are to blame. (Heather Harris/NOAA-ESA Permit #15634 via AP)

MONTEREY, Calif. — Scientists were documenting stranded sea turtles on California’s beaches nearly 40 years ago when they noticed that leatherbacks — massive sea turtles that date to the time of the dinosaurs — were among those washing up on shore. It was strange because the nearest known population of the giants was several thousand miles away in the waters of Central and South America.