U.S. West Coast Groundfish Bottom Trawl Survey (WCGBTS)

The West Coast Groundfish Bottom Trawl Survey (WCGBTS) is a key source of fishery-independent data used for stock assessments and groundfish management.

The Survey occurs from May to October each year. Our coverage extends from Cape Flattery, Washington (U.S. - Canada border) south to the U.S.-Mexico border. We cover this area twice each year using chartered commercial fishing vessels and an Aberdeen-style trawl net. The Survey uses a stratified random sampling design and adheres to strictly standardized trawl gear and rigging specifications. More methods information can be found in the 2017 Trawl Survey Technical Memorandum.

We check catch and haul-related information at sea. Vessels are equipped with modern instrumentation to monitor trawl performance and net position, including bottom contact sensors, global positioning systems (GPS), multiple depth sounders, and radar. A variety of oceanographic sensors are attached directly to the trawl net to collect water column profiles of temperature, salinity, turbidity, fluorescence, light, and dissolved oxygen for each haul at depth.

We encounter about 90 commercially fished stocks, including the following species categories:

Sharks and skates.
Flatfishes.
Rockfishes and thornyheads.
Roundfishes (lingcod, greenlings, and sablefish).
We sort, measure and weigh all captured fish and invertebrate species. Doing so ensures that data are accurate and current annually.

We collect the following biological samples on a subset of species for further analysis:

Otoliths and other structures (vertebrae, fin rays, spines) are for ageing
Finclips for genetics
Stomach contents and tissue samples for stable isotope and diet analysis
Gonads for maturity and reproductive analysis