Vol. 53 - Alaska Resources Library and Information Services

fined somewhat based on data from 1981 that was used for molt-frequency
analysis (Fig. 5.6).
The samples used for this analysis, late May
through about June 10, showed all larvae were SI zoeae (90-99%).
From
June 13 to July 4 SII were dominant, and after July 11 megalopae were
the most abundant stage.
Assuming that megalopae require about one month
for development (similar to Tanner larvae, Section 4.0), the majority of
the population would have metamorphosed in mid- to late-August in 1981.
Add to this time about one month for SI zoeal development, and total
planktonic time for this taxon would be about 3.5 months.
Distribution:
Larvae of this taxon were found at 42% of all stations
sampled in 1976-1981.
Of these stations, 77% were collected in May and
June, which was therefore used as the time frame for analyses of interannual
densities between strata.
During May and June, larval Oregoniinae
were most frequently (> 60% of stations) collected in strata 1, 4, 5, 9,
10 and 12, and least frequently (< 30% of stations) in strata 7, 8, and
11 (Table 5.6; See Fig. 2.8 for strata). This May/June distribution and
density are shown in Figures 5.7, 5.8, and 5.9 for the years 1978, 1980
and 1981, respectively. There tend to be fewer larvae over the middle
and inner shelf to the extent they were collected, and more along the
100 m isobath and outer shelf. High densities are shown near western
Unimak Island in all years (Figs. 5.7-5.9) which is likely due to the
presence of Oregonia gracilis spp. that were found in high abundance
nearshore in 1982 (Armstrong, unpublished data).
Density:
Because sampling within all strata in each year was not
consistent, it is somewhat difficult to compare larval densities between
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