Vol. 53 - Alaska Resources Library and Information Services

2.1.2 Field Gear and Sampling Methods
Physical Environment. Temperature and conductivity data were collected
with the Miller Freeman's CTD system. Depth-specific conductivity and
temperature were later converted to salinity using a NOAA computer
algorithm. Near-surface and near-bottom salinity data were selected for
correlation with the observed larval and juvenile red king crab distributions.
Near-surface, instead of surface, salinity (and temperature)
values were selected for two reasons: 1) the shallowest CTD readings
varied between 0.2 and 1.5 m; and 2) a subsurface value was thought to
be more representative for correlation to organisms collected in oblique
plankton tows. The near-bottom values were generally recorded about 5 m
off the bottom.
Sediment samples were collected primarily with a Shipek grab during
cruises 83-1 and 83-3; a few sediment samples were taken with a Van Veen
grab during cruise 83-1. A sample of surface sediment was scooped from
the grab sample, placed in a labeled plastic bag and frozen for later
analysis. A field description of each sediment sample was recorded in
the chief scientists'field notes during cruise 83-1.
During cruise 83-5 (September), a side scan sonar unit was used in an
attempt to discern gravel substrates from silt and sand. A 500 kH z
Klein Associates, Inc. fish was towed at approximately 15 m from the
bottom. Scope (wire out) and towing speed were varied to achieve
distance above bottom, but in general the target speed relative to the
substrate was 2 knots. A path width of 150 m was selected. Results
were printed with a Klein Associates 521 T continuous recorder. Trynet
trawls and Shipek grabs were then collected to ground proof the side
scan traces. Two station locations were selected for intensive side
scan sonar surveys: PM730 (Figure 2.1-3) and KB2*4 (Figures 2.1-3 and
2.1-5).
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