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Vol. 53 - Alaska Resources Library and Information Services

Vol. 53 - Alaska Resources Library and Information Services

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at 21% of all stations sampled <strong>and</strong> greatest densities were found on both<br />

sides of the 100 m isobath from St. George to Unimak isl<strong>and</strong>s (Fig.<br />

5.13). Densities were also high near Amak Isl<strong>and</strong> between Bechevin Bay<br />

<strong>and</strong> Izenbek Lagoon.<br />

Considering the relationship between this family of<br />

crab <strong>and</strong> bivalve molluscs, larval crab distribution is somewhat in accord<br />

with infaunal distribution <strong>and</strong> abundance of bivalves in the southeastern<br />

Bering Sea (McDonald et al. 1981).<br />

The frequency-of-occurrence<br />

of pinnotherid larvae within strata is shown in Table 5.7 <strong>and</strong> reflects<br />

high abundance in strata 2, 5, <strong>and</strong> 6.<br />

The pattern of larval distribution shown in Figure 5.13 was further<br />

analyzed by averaging larval densities within depth intervals of 50-74<br />

m, 75-125 m, 126-200 m <strong>and</strong> > 200 m for the years 1978, 1980 <strong>and</strong> 1981<br />

(Figs. 5.14 a, b, c).<br />

Most larvae occurred between 75-125 m where mean<br />

densities in 1978 ranged from 2178 to 10,603 larvae/100 m 2 (Fig. 5.14a).<br />

There was an obvious drop in larval density both shallower <strong>and</strong> deeper<br />

than this depth interval in all years analyzed (Figs. 5.14 a, b, c),<br />

where densities were zero to a few hundred larvae/100 m².<br />

Interannual<br />

differences in density during May/June were difficult to assess but<br />

there is an indication of reduced density in the 75-125 m interval of<br />

strata 1 <strong>and</strong> 2 in 1980 <strong>and</strong> 1981 (about 200 larvae/100 m 2 ; Figs. 5.14 b<br />

<strong>and</strong> c) compared to 1978 (2178/100 m2).<br />

Summary<br />

1) Pinnotheridae larvae were collected at 21% of all the stations<br />

sampled during 1976-1981.<br />

675

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