The Northwest Fisheries Science Center's Cooperative U. S. West Coast Groundfish Bottom Trawl Survey: Methods and Environmental Sampling

The NOAA NMFS Northwest Fisheries Science Center (NWFSC) currently conducts a number of groundfish research and monitoring projects that are cooperative and collaborative with the fishing industry. These include a West Coast Groundfish Bottom Trawl Survey (WCGBTS), which is the primary source of fisheries independent data for west coast stock assessments. The fisheries management plan for the west coast includes 90+ groundfish species and biological data from the survey are sufficient to populate assessments for ~46 species. Fishery and environmental sampling is conducted annually (May–October) using chartered commercial trawlers within the California Current System from U.S.–Canada to U.S.–Mexico at depths of 55 to 1280 m. The survey utilizes a stratified-random sampling design and efficient sampling techniques to maximize coverage while minimizing costs. In the context of cooperative research programs, advancements in sampling technologies have allowed new types of data to be collected during traditional NMFS surveys. For example, environmental sensing packages are attached to trawls and record a full array of environmental parameters (e.g., depth, temperature, salinity, dissolved oxygen, chlorophyll fluorescence, turbidity, and light). These improved environmental sensing capabilities have led to collaborations with academic partners. In 2007, the NWFSC added an environmental sampling program to the WCGBTS that included collaboration with physical oceanographers at Oregon State University. This program was initiated, in part, in response to hypoxia that was observed on the continental shelf of the Pacific Northwest, in a region not previously characterized by hypoxic conditions. In 2012, the NWFSC began deploying a Simrad EK60 transceiver/transducer in an effort to classify bottom types based on echo features. The resulting availability of highly resolved underwater data from sensors and transducers provides an opportunity to develop methodologies that better define species-habitat/environmental associations, and to include such information in stock assessment frameworks.