U.S. Territorial Bottomfish Stocks Less Healthy Than Previously Assessed

August 27, 2019

Scientists assessed the stocks of bottomfish in the Commonwealth of the Northern Mariana Islands, Guam, and American Samoa, and the results varied.

Bottomfish fishing gear off CNMI.

Bottomfish fishing gear off of the Commonwealth of the Northern Mariana Islands. Photo: NOAA Fisheries/Joseph DiBattista.

Bottomfish stocks in three U.S. Pacific territories are not as healthy as previously thought, according to a new report from NOAA’s Pacific Islands Fisheries Science Center. Scientists recently completed three new stock assessments for bottomfish species in the Commonwealth of the Northern Mariana Islands (CNMI), Guam, and American Samoa

Stock assessment results differed among the regions. For the CNMI, the stock was healthy (not overfished and not experiencing overfishing). For Guam and American Samoa, the stocks were less healthy. The Guam stock was overfished but not experiencing overfishing, and the American Samoa stock was both overfished and experiencing overfishing. 

Stock status assessments for bottomfish of the CNMI, Guam, and American Samoa.

Stock status is determined on the basis of stock size (x-axis) and fishing rate (y-axis). In the green area, there are many fish (not overfished) and the fishing rate is low (not overfishing). In the red area, there are too few fish (overfished) and the fishing rate is too high (overfishing is occurring). In the lower left yellow area, the stock size is low, but the fishing rate is not high enough to cause a further decrease in stock size. In the upper right yellow area, stock size is high but the fishing rate is high enough to cause a decline below acceptable levels.

Bottomfish in the Territories

Bottomfish include species of snapper, emperor, grouper, and jack. The assessments considered the health of multi-species groups of bottomfish in each territory. The bottomfish group in American Samoa has 11 species and the groups for the CNMI and Guam each have 13 species. The data showed that there were three species of bottomfish most commonly caught by fishers:

Bluestripe snapper (Lutjanus kasmira)

Bluestripe snapper
  • Samoan name: savane

  • Chamorro/Carolinian name: funai/saas

Redgill emperor (Lethrinus rubrioperculatus)

Redgill emperor
 
  • Samoan name: filoa-paomumu

  • Chamorro/Carolinian name: mafute/atigh

Flame snapper (Etelis coruscans)

Flame snapper
 
  • Samoan name: palu-loa

  • Chamorro/Carolinian name: buninas/taighulupegh

Data Sources and Analyses

The stock assessments used creel (recreational, subsistence, and commercial fishing) survey data and commercial fishing sales receipts for information on fish catch and abundance trends. The creel surveys are interviews of fishers fishing from the shore and from boats. Territorial agencies have conducted these surveys in Guam since 1982, American Samoa since 1986, and the CNMI since 2000.

The assessment results for Guam and American Samoa differ from previous stock assessments. The findings were reviewed by an independent panel of scientists and a member from the Western Pacific Regional Fisheries Management Council’s Science and Statistical Committee. They considered the data analyses and modeling approach to be improvements over previous assessments. 

Previous assessments only included creel survey data from fishing trips with a high amount of bottomfish species in the catch. This approach may have created a bias in the data by excluding fishing trips that tried to catch bottomfish but did not. The new analyses reduced this bias by including all fishing trips that used gear that most commonly catch bottomfish, even if no bottomfish were caught. 

The report will now go to the Western Pacific Regional Fisheries Management Council’s Science and Statistical Committee for evaluation before it is used to inform fishery management decisions. In addition, NOAA Fisheries will use information in the stock assessments to inform official stock status decisions.

Last updated by Pacific Islands Fisheries Science Center on August 28, 2019

Bottomfish