The number of US fisheries deemed "overfished" declined in 2019, with 22 stocks subject to overfishing versus 2018's status of 26 stocks -- a sign some rebuilding efforts are showing results.

The National Oceanic and Atmospheric Administration (NOAA) Report to Congress on the Status of US Fisheries, released Thursday, surveys fisheries in US territorial waters annually to determine the status of stocks deemed troubled under NOAA's management guidelines.

In its report, NOAA designates fisheries under excessive pressure as either "overfished" or subject to "overfishing."

A stock being "overfished" has a population size that is too low, jeopardizing its ability to reach maximum sustainable yield (MSY), or a long-term sustainable catch. Under NOAA's definition, an "overfished" stock is impacted not just by harvesting, but other environmental factors as well.

The majority of both "overfished" stocks and stocks subject to "overfishing" have limited commercial impact.

Recovering stocks include Chinook, flounder

This year, 10 stocks were removed from the "overfished" list including king salmon from the Columbia River Basin, summer flounder from the Mid-Atlantic coast and yellowtail flounder in the Gulf of Maine and New England waters, among others.

However, eight stocks were also added to the overfished list in this year's report. Those include gray triggerfish and greater amberjack from the Gulf of Mexico, greater amberjack, red grouper and bluefish from the southern Atlantic coast, the northern subpopulation of Pacific sardines, white hake from the Gulf of Maine/Georges Bank, and winter flounder from Georges Bank.

"The stocks added to the 2019 overfishing and overfished lists illustrate several challenges inherent in fisheries management," NOAA said.

For example, the agency said although Pacific sardine commercial fishing has been banned since 2015, changing ocean conditions have resulted in "years of poor reproduction that have reduced the Pacific sardine population to very low levels."