State fishing regulators have issued a second delay in the commercial crab season stretching north from the Sonoma-Mendocino county line. The postponement, which stretches to the coastal waters off Del Norte County, is meant to allow Dungeness crab in the area more time to mature and gain weight, state regulators said.

Fishing will now open Dec. 31, barring poor results from the next round of testing, scheduled for Dec. 21. The zone north of Sonoma County normally opens Dec. 1.

The commercial crab season opened on the Sonoma Coast south of Bodega Bay on Nov. 15. A delay remained in place north of Bodega Head until Saturday because of isolated samples of Dungeness crab with elevated levels of domoic acid, a naturally occurring, algae-related neurotoxin that can accumulate in crab and their viscera.

Samples taken outside the Russian River since Nov. 17 have come back clean, according to the California Department of Public Health. Health officials still say the safest way to consume crab is to eat the meat only and to discard any cooking water.

You can reach Staff Writer Mary Callahan at 707-521-5249 or mary.callahan@pressdemocrat.com.