Table of Contents

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

Fish abundance data from MOC-10 trawls.

Methodology:

Field work was done on four cruises conducted during the austral fall and winter. Cruises 1 (2001) and 3 (2002) were aboard the Antarctic Research Support Vessel (A.R.S.V.) Laurence M. Gould from April to June; cruises 2 (2001) and 4 (2002) were aboard the Research Vessel Ice Breaker (R.V.I.B.) Nathaniel B. Palmer from July to September.

Samples were collected with a 10m2 MOCNESS (MOC-10) outfitted with six 3mm mesh nets. The initial net fished obliquely to depth with each subsequent net fishing a discrete depth layer upward to the surface. At stations with depths>1000 m, layers sampled were 0-1000, 1000-500, 500-200, 200-100, 100-50, and 50-0 m. At stations with depths >500 m, layers sampled were 0-500, 500-300, 300-200, 200-100, 100-50, and 50-0 m. At stations with depths <500 m, sample layers were modified to provide optimal coverage of the water column with the five discrete-depth nets.

A total of 62 MOC-10 trawls were done, 22 each in the fall of 2001 and 2002, and 9 each in the winter of 2001 and 2002 (Table 1). Trawls were conducted at various times throughout the day. In the fall, 37 trawls occurred at night (18:00-06:00 h), 1 in daylight, and 6 at dusk. In the winter, seven trawls occurred at night, seven in daylight, and four at twilight. Towing speed for all tows was 1.5-2.2 knots. Tows in pack ice were conducted in leads created by the ship's wake with the A-frame in to minimize the chance of hooking the wire on ice floes. When ice conditions dictated, the ship first traversed a trawling transect prior to deployment and then backtracked over the same course through the created lead to insure that adequate speed could be maintained for the duration of the tow.

Fig. 1. Trawling sites for (A) fall and (B) winter SO GLOBEC cruises; blue circles: 2001 and red circles: 2002.

All samples were preserved in a 5-10% buffered formaldehyde solution, shipped to the laboratory for analysis, and then stored in 50% isopropanol. Fish were sorted from each sample, identified to lowest possible taxon, enumerated, measured (mm; standard length (SL)), and weighed (mg; wet mass (WM)). WM of formalin preserved specimens has been found to not differ significantly from fresh specimen WM (Lancraft, Donnelly and Torres, unpublished data). For many catches, selected specimens were removed from the sample prior to preservation and stored frozen. These specimens were identified to species and measured prior to freezing and their WM determined from regressions generated from numerous previous datasets (Donnelly and Torres, unpublished data).

Species' abundance and biomass are expressed as normalized values (#, gWM10⁴ m³ water volume filtered). Discrete-depth values were calculated for each species by dividing their number or WM in the catch by the water volume filtered for a particular depth stratum.​

The fundamental objectives of United States Global Ocean Ecosystems Dynamics (U.S. GLOBEC) Program are dependent upon the cooperation of scientists from several disciplines. Physicists, biologists, and chemists must make use of data collected during U.S. GLOBEC field programs to further our understanding of the interplay of physics, biology, and chemistry. Our objectives require quantitative analysis of interdisciplinary data sets and, therefore, data must be exchanged between researchers. To extract the full scientific value, data must be made available to the scientific community on a timely basis.

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).