California sushi eaters, watch out: San Francisco-based public awareness campaign Got Mercury? released the results from its most recent undercover fish testing operation earlier today. The data are pretty scary, and they're making news. But it's a little unclear whether the alarm is totally warranted, and—more importantly—what we should be doing about it.

The campaign explains that they "randomly selected 41 grocery stores in California to purchase fresh and frozen samples of swordfish, ahi tuna or yellowfin tuna, and salmon," which they then submitted to laboratory analysis. Their findings include the startling fact that more than a third of the grocery store fish studied had levels of methylmercury in excess of the the FDA do-not-sell limit of 1 part per million, with swordfish being by far the worst offender. In fact, only 6 of the 32 swordfish samples analyzed came in below 1 part per million, and one fish, purchased at a Ralph's in Los Angeles, had 3 parts per million.