Multifaceted Research Expedition Yields Valuable Information about Bottomfish and Associated Habitat in American Samoa

During March 2012, PIFSC scientists on the NOAA Ship Oscar Elton Sette completed a multifaceted research mission in the inshore waters around American Samoa. The research was focused on Northeast Bank, Two Percent Bank, South Bank, and Tutuila. The primary missions were to describe the oceanographic characteristics of the fishing banks around American Samoa; collect adult specimens of snappers and groupers for life history studies (age & growth, maturation); characterize the distribution and abundance of early life stages of insular pelagic species and pelagic forage assemblages; collect samples of neuston and fish stomachs to determine the distribution and abundance of microplastics; collect specimens for studies of copepod genetics; and study the behavior of deepwater bottomfishing gear.

Location of primary survey sites for the American Samoa bottomfish research expedition (white squares).
Location of primary survey sites for the American Samoa bottomfish research expedition (white squares).

The expedition was led by Ecosystems and Oceanography Division scientist Don Kobayashi and involved colleagues from the Center's Fish Life History Program and partners from the American Museum of Natural History, University of Hawaii (UH) Joint Institute for Marine and Atmospheric Research, UH Department of Oceanography, NOAA's Teacher-at-Sea Program (EARTHS Magnet School), and the American Samoa Department of Marine and Wildlife Resources (DMWR).

During the daytime, various operations were conducted: a conductivity-temperature-depth instrument was deployed to obtain vertical profiles of water temperature and conductivity from the sea surface down through the water column; a Mini-Manta neuston net was towed at the sea surface to collect microplastics and plankton; a 1.8-m Isaacs-Kidd midwater trawl was used to sample early life history stages of fish and forage biota; a 1-m obliquely towed ring net was used to collect copepods; bottomfishing was carried out from small boats to collect bottomfish specimens; and a bottom camera bait station ("BotCam") was deployed in conjunction with the bottomfishing. Nighttime operations included deployment of a Cobb midwater trawl to sample fish biota and a 1-m obliquely towed ring net to sample copepods.

During the fishing operations, adult specimens of eteline snappers were collected to support studies of age-and-growth and maturity, both key needs for improved stock assessment. Snappers were caught both from small boats (17 boat-days of effort over 10 days, covering 277 drift fishing stations and 5.3 hours of fishing) and from the Sette. Fishing from small boats occurred primarily along depth contours ranging from 50 to 150 fathoms, directly over the offshore fishing banks. Fishing from the Sette was conducted on 4 days, in the late afternoon and evening.

Three BotCam operations were conducted in conjunction with the small-boat bottomfishing operations to collect video observations of fishing gear behavior and the process of fish capture. All three deployments yielded useable stereo video streams which will be further processed by video technicians in the laboratory. Initial examination of BotCam footage indicated that in one operation fishing gear passed in front of or on top of the BotCam unit several times over the course of the day. Another sequences of photos captured the dispersal of chum from a palu bag and hooking of a snapper (Pristipomoides).