Vol. 53 - Alaska Resources Library and Information Services

larval densities were generally low (< 500/100 m²), but greatest
abundance always occurred in May (1000 larvae/100 m²) over stratum 2.
The frequency of occurrence of larval crangonids in the 1981 samples was
high (present in 75-100% of the samples), whereas in other years crangonids
were taken less frequently (in 33-80% of the samples).
The lowest
mean densities were consistently taken in 1980.
Table 6.8, the crossshelf
comparison of mean densities of Crangon spp. larvae during May and
June PROBES 1978, demonstrates three trends.
First, the absence of any
Crangon spp. larvae beyond the shelf break; second, in the outer shelf
domain, highest densities were found in the north and south of the St.
George Basin; third, crangonids were less abundant over the middle shelf
with mean density between 260-375 larvae/100 m². Crangonids were
consistently less abundant than either the pandalids or hippolytids.
MOCNESS data from PROBES 1980 and 1981 cruises were analyzed but
there were insufficent stations during 1980 for a complete workup of
vertical depth distribution.
Only 5 stations out of a possible 26 had
more than 6 larvae per station and a sample size of 5 stations was
regarded as unacceptable. For the 1981 data, a homogeneous distribution
of Crangon spp. larvae throughout the water column is shown in Fig.
6.32. Crangon spp. larvae were distributed between 0-80 m with 16% in
the upper 20 m, 47% in the upper 40 m, 76%
in the upper 60 m, and 93% in
the upper 80 m.
Summary:
1) Hatchout of Crangon spp. begins in late March and the larvae remain
in the water column until early August.
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