KETCHIKAN, Alaska — Several commercial Alaska oyster farmers are back in business after state testing showed their respective shellfish contained greater-than-allowed levels of naturally occurring toxins that cause paralytic shellfish poisoning, a potentially fatal illness.

All bivalve molluscan shellfish, which include oysters, mussels, clams, geoducks and scallops, can contain low and high levels of toxins that cause paralytic shellfish poisoning.

Aby Twyman, the director of operations for Shikat Bay Oysters, said having lost an estimated $25,000, the Alaska oyster farm reopened July 17, and like others, has been able to remain open after a six-week-long, state-mandated shutdown.

Twyman said her family has been running the business since 2009 without incident until failed state testing for toxins that cause paralytic shellfish poisoning in 2016 closed it for four weeks.

Longtime-but-now-retired shellfish farmer Sharon Gray said Canoe Lagoon Oyster Co. was forced to close for about a month.

She said it is not the ever-present toxins that cause paralytic shellfish poisoning of Alaska waters that worries her. It is the current regimen of state testing, Gray said, that drive the long closures.

New farms complete more stringent state testing, but established commercial oyster farmers in the state are required to test their product on a weekly basis during the summer months, with monthly tests required during the winter.

A failed test — those with toxin that cause paralytic shellfish poisoning levels at or above 80 micrograms per 100 grams of shellfish — requires the associated mariculture operation to close, until three consecutive clean tests are produced, the Ketchikan Daily News reported ( ).

Those tests are staggered, with a minimum of four days required to lapse between test samples.

“Every year it seems like the testing in itself gets ramped up and ramped up and ramped up in certain ways that, to me, with my experience, is based on … not science, but so much paranoia,” she said.

“With our short tourism season here in Southeast Alaska, what they’ve done now, if you don’t pass a test — if you go over 80 (micrograms), and you fail a test — you have to pass three tests before you’re allowed to sell, and (the tests) are spaced apart,” Gray said.

Rocky Bay Oyster Co. co-owner Ken Horn said the Wrangell-area oyster farm had to close earlier in the summer for about two weeks, but its oysters since have been testing clean.

“Let’s just say that you’re shipping off $2,000 worth of oysters per week … some guys are shipping off anywhere from $3,000 to $4,000 worth of oysters a week to these wholesalers, and if you can’t ship your oysters off, you’re just done,” Horn said. “It really puts a hurting on you.”

“It would be similar to somebody losing their crops due to a flood,” he added. “So if you lose your crops, you know, what do you do?”