In a status review of the pinto abalone, the National Marine Fisheries Service declined to list the species as endangered, arguing the six-inch-long sea snail isn't under the threat of extinction despite evidence of the population's struggles.

"The best available data indicate that pinto abalone abundance has declined in many areas throughout the species' range due to fisheries harvest," the National Marine Fisheries Service, or NOAA Fisheries, admitted in the report. But officials say baseline numbers -- population data prior to commercial fishing harvests -- are difficult to estimate, complicating the process of understanding population trends.

Ultimately, biologists and policy-makers at NOAA Fisheries decided the threat of over-harvesting and the lack of regulatory enforcement were not compelling or severe enough to warrant further protections. The pinto abalone (Haliotis kamtschatkana) will instead remain on the agency's "Species of Concern" list.

The latest status review was prompted by two petitions filed last year by conservation and environmental activist groups, including Natural Resources Defense Council and the Center for Biological Diversity.

"It's disappointing. We believed that the pinto abalones qualified for the list," Brad Sewell, a senior attorney for Natural Resources Defense Council, told the Voice Chronicle. "The only way of saving the species is to address the health of the species early on and get it back to robust diverse populations."

The petitioners claim the pinto abalone's population has declined as much as 90 percent in recent decades. The species can be found in small isolated clusters up and down the West Coast, from the Baja peninsula to Alaska.