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Vol. 53 - Alaska Resources Library and Information Services

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during PROBES 1980 <strong>and</strong> 1981 sampling from April to July.<br />

The total<br />

cumulative percentages of larvae in each depth interval were:<br />

15-28% in<br />

the upper 20 m; 46-62% in the upper 40 m; 70-79% in the upper 60 m; <strong>and</strong><br />

94% in the upper 80 m. This homogeneous distribution from 0-80 m is<br />

similar to the pattern for P. borealis. MOCNESS data for PROBES 1981<br />

were analyzed by month (Fig. 6.23).<br />

Larvae were concentrated in the<br />

40-80 m depths during April, in the 0-40 m interval during May <strong>and</strong> June,<br />

<strong>and</strong> homogeneously throughout 0-80 m by late June <strong>and</strong> July.<br />

Examining<br />

the pattern of larval depth distribution within each depth interval<br />

(Fig. 6.23) clearly shows the highest percentage of larvae (about 40%)<br />

in the 20-0 <strong>and</strong> 40-20 m intervals during May <strong>and</strong> June, <strong>and</strong> a high percentage<br />

of larvae (about 30%) in the 80-60 m interval both in April <strong>and</strong><br />

then again in late June <strong>and</strong> July.<br />

This changing pattern of hippolytid<br />

larval depth distribution might be correlated to food availability or<br />

temperature, light <strong>and</strong> other factors.<br />

Correlations are difficult to<br />

perform since the hippolytids are a multi-species group.<br />

Summary:<br />

1) Larvae of some hippolytids hatch out as early as March, while other<br />

species not until April or May.<br />

2) Hippolytids are distributed widely over the St. George Basin, into<br />

the mid-shelf domain <strong>and</strong> beyond the shelf break.<br />

3) Greatest densities occurred beyond the shelf break <strong>and</strong> along the<br />

Aleutian Isl<strong>and</strong>s, especially near Unimak Pass.<br />

Mean densities<br />

beyond the shelf break ranged from 1000-2000 larvae/100 m 2 in May<br />

<strong>and</strong> June during years from 1977-1981.<br />

750

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