SAN FRANCISCO — The California Department of Fish and Wildlife has extended an emergency closure of the commercial rock crab fishery in Northern California.

The commercial rock crab fishery north of Pigeon Point in San Mateo County to the Oregon border has been closed since last fall after state health agencies found unhealthy levels of domoic acid.

The closure was set to expire Tuesday but will now remain in effect until officials determine that domoic acid levels no longer pose a significant risk to public health.

The fishery is clean from Bodega Bay south along the entire California coast.

The acid is a potent neurotoxin produced naturally in marine algae whose levels can increase under certain ocean conditions.