A collapse of the razor clam population across Kenai Peninsula beaches has prompted the Alaska Department of Fish and Game to close most of them to clamming for the rest of the year, the first time biologists have imposed such a drastic measure.

“It’s such an important resource,” said Carol Kerkvliet, a Homer-based biologist with Fish and Game. “All the information we have points in one direction, that these beaches need to be closed.”

The latest information is a 2014 survey of the clam populations on Kenai beaches. It found:

The population at the Clam Gulch beach was 89 percent lower than average.

• At Ninilchik South beach, the Kenai’s most popular, the population was down 82 percent.

• At both locations, the number of juvenile clams was also down sharply -- ranging from 36 percent to 86 percent. That’s an indication that no recovery is on the horizon.

The decline has worsened over the decades. The peak year was 1994, when Fish and Game estimated the harvest at 1.3 million clams captured over 48,000 digger days (a clam-digger spending at least part of a day on the beach). By 2013, the last year for which information is available, the harvest was down to 174,000 clams over 24,000 digger days.

Similarly, state harvest surveys showed that average number of clams harvested by each digger declined from 25 early last decade to 7 in 2013.

Even that is more than zero.

“If it were harvest-driven, we would have seen the effects earlier,” Kerkvliet said. “Some type of environmental factor is playing a role in this.”