Vol. 53 - Alaska Resources Library and Information Services

in 1981 due to the sampling patterns employed during those years.
No
spiny larvae were ever found in the middle shelf domain (strata 9, 1,
and 6) during any of the cruises.
Table 6.9 compares mean larval densities during April and May from
NOAA 1977 with densities during May and June from PROBES 1978. Generally
higher mean penaeid densities occurred during 1977 for all strata
except stratum 8. In addition, the pattern of increasing abundance with
increasing station depth is clearly apparent; none was found over the
middle shelf, but an average of 4390/100 m 2 was found in stratum 3 over
the shelf break.
Vertical Distrubtion:
Of all the shrimp, these spiny larvae were the
most homogeneously distributed in the water column from 0-80 m (see Fig.
6.36). Based on PROBES 19801 MOCNESS data, a cumulative total of 20% of
penaeid spp. larvae appeared in the upper 20 m, 45% in the upper 40 m,
75% in the upper 60 m, and 98 % in the upper 80 m. Low abundance of
these spiny larvae in PROBES 1980 samples precluded any depth distribution
analysis for that year.
Summary:
1) A type of spiny larva, tentatively assigned to the family
Penaeidae, was taken less frequently than the other families of
shrimp.
2) It was found predominantly beyond the shelf break in deep water
(> 200 m).
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