Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Program Information
• Funding

U.S. GLOBEC Northeast Pacific California Current System Mesoscale Process Studies
Trawl Catch Data

Contacts for this data set are:
Dr. Richard Brodeur
Northwest Fisheries Science Center
National Oceanographic and Atmospheric Administration
Newport, OR 97365
Phone: 541-867-0336
Email: Rick.Brodeur@noaa.gov

Robert Emmett
Northwest Fisheries Science Center
National Oceanographic and Atmospheric Administration
Newport, OR 97365
Phone: 541-867-0109
Email: Robert.Emmett@noaa.gov

Suzan Pool
Cooperative Institute of Marine Resources Studies
Oregon State University
Newport, OR 97365
Phone: 541-867-0195
Email: Suzan.Pool@noaa.gov

During juvenile salmonid trawling cruises, additional sampling included CTD profiles, neuston net tows, and Niskin bottle water collections for chlorophyll a. At most stations, data on all parameters were collected.

Results: Detailed analyses of the nekton trawl catches for 2000 are presented in Brodeur et al. (2004) and for jellyfish for both years in Suchman and Brodeur (2005).

References
Brodeur et al., 2004.
Suchman et al., 2005.

Last modified: March 22, 2005

Methods
At each station, a Nordic 264 rope trawl built by Nor'Eastern Trawl Systems, Inc. was towed in surface waters by a chartered fishing vessel (F/V Sea Eagle in 2000 and F/V Frosti in 2002). It was towed with about 300 m of warp for 30 min at 1.5 m/sec with a pair of 3.0-m foam-filled trawl doors and 90.7-kg weight chains to spread the mouth open. Except for two mid-water trawling events, six A-4 Polyform floats were clipped to wingtips and the headrope to fish the trawl at the surface. The trawl has a maximum mouth opening of approximately 30-m wide x 18-m high. Mesh sizes ranged from 162.6 cm in the throat of the trawl near the jib lines to 8.9 cm in the codend. To maintain catches of small fish and squid, a 6.1-m long, 0.8-cm knotless liner was sewn into the codend. All but several tows were 30 min in duration. The majority of trawls were done during daytime, although a few were done at dawn and dusk and two diel series were completed in 2002.

All juvenile salmon caught were immediately frozen for laboratory analysis. All fish, squid, and large jellyfish caught were counted and up to 50 of them measured at sea. However, when very large catches of a species occurred, a subsample was measured, counted, and weighed; remaining individuals were mass weighed and total count estimated from known number/kg. When the trawl was full, weight of the total catch was estimated and species counts derived from a subsample as just described. Catches were standardized to number per 10⁶ m³.

In the laboratory, all frozen juvenile salmonids were weighed prior to dissections for subsamples of growth, condition, pathology, genetic analysis, and food habits. As large subadult/adult salmonids were released shortly after being captured, their weights were estimated from length-weight regressions. Also, common species of non-salmonid fish and squids not weighed at sea had their weights computed from length-weight regressions where their lengths were available. For those individuals without length data, station or cruise-wide average of number/kg was used to estimate weights.

Program in a Nutshell

Goal: To understand the effects of climate variability and climate change on the distribution, abundance and production of marine animals (including commercially important living marine resources) in the eastern North Pacific. To embody this understanding in diagnostic and prognostic ecosystem models, capable of capturing the ecosystem response to major climatic fluctuations.

Approach: To study the effects of past and present climate variability on the population ecology and population dynamics of marine biota and living marine resources, and to use this information as a proxy for how the ecosystems of the eastern North Pacific may respond to future global climate change. The strong temporal variability in the physical and biological signals of the NEP will be used to examine the biophysical mechanisms through which zooplankton and salmon populations respond to physical forcing and biological interactions in the coastal regions of the two gyres. Annual and interannual variability will be studied directly through long-term observations and detailed process studies; variability at longer time scales will be examined through retrospective analysis of directly measured and proxy data. Coupled biophysical models of the ecosystems of these regions will be developed and tested using the process studies and data collected from the long-term observation programs, then further tested and improved by hindcasting selected retrospective data series.

U.S. GLOBEC (GLOBal ocean ECosystems dynamics) is a research program organized by oceanographers and fisheries scientists to address the question of how global climate change may affect the abundance and production of animals in the sea.

The U.S. GLOBEC Program currently had major research efforts underway in the Georges Bank / Northwest Atlantic Region, and the Northeast Pacific (with components in the California Current and in the Coastal Gulf of Alaska). U.S. GLOBEC was a major contributor to International GLOBEC efforts in the Southern Ocean and Western Antarctic Peninsula (WAP).