Vol. 53 - Alaska Resources Library and Information Services

etween Unimak Island and Port Moller, off Port Heiden and off Hagemeister
Island in the Togiak Bay area.
Side Scan Sonar. Side scan sonar surveys were successfully employed in
order to discern gravel and cobble substrates from silt and sand substrates.
Portions of sonar traces showing silt-sand and gravel-cobble
areas are reproduced in Figures 3.1-16 and 3.1-17, respectively.
Although the project budget precluded analysis of ground truth samples,
subjective observations of Shipek dredges and try net and rock dredge
hauls indicated that the samples support these side scan interpretations.
Intensive side scan sonar surveys, each approximately one nautical
mile square (3.43 km²), were conducted at stations PM630 and KB2*4
during cruise 83-5. The Port Moller survey exhibited no discernible
heterogenity in the stubstrate. The Kvichak Bay survey yielded
transects with apparent areas of gravel-cobble such as that shown in
Figure 3.1-17. When the transects for the survey were joined and drawn
to scale, the gravel-cobble areas emerged as long, narrow beds, oriented
approximately parallel to the axis of Kvichak Bay. The beds were 20-30
m wide and between 50 and 800 m long. A graphic representation of the
beds in the Kvichak Bay survey is shown in Figure 3.1-18.
3.2 Larval Distribution and Abundance
3.2.1 Horizontal Distribution and Abundance
Distribution. Larval densities along the North Aleutian Shelf from
Unimak Island to Port Heiden were very low during all times sampled
(late April, late May, mid-June) in 1983 compared to densities recorded
for 1982 over the same area. Data from the two week period of about
April 23 to May 7 show that larvae were most abundant offshore of Black
Hills to western Port Moller (Figure 3.2-1). Larvae were virtually
absent in the area from western Unimak Island to Izembek Lagoon, and
north of latitude 56°40' (about Port Moller) to the limit of sampling
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